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1. 12 Copy the hou input file to the ACS SASSI working directory that was created in the ANSYS matrix generation tutorial This folder should also include the input files for the SITE POINT and ANALYS modules 4 2 2 Embedded SSI Models For embedded SSI models the cdb files for both the ANSYS structure model and the ANSYS excavation model are needed There are 19 steps to create the HOUSEFSA module input file hou 1 Create a working directory in which the HOUSE input file hou of the HOUSEFSA will be created using SUBMODELER 2 Copy the ANSYS cdb files for the structure and excavation models into the SUBMODELER working directory 3 Start SUBMODELER 4 Type actm 1 to a switch to model ID number 1 which will be used for the structure model 5 Convert the ANSYS structure model into the ACS SASSI format using SUBMODELER by selecting Model gt Converters gt ANSYS cdb from the menu bar A dialog box will open In the dialog box input the following data a Inthe Input File Name box input the ANSYS cdb file name including path by typing or browsing b In the Output pre File Name box input the corresponding pre file name including path Optional step c In the Save Converted Data to Model Number box enter the model ID number for the structure model By default this will save the converted model to model 0 The model ID number entered here should be an unused ID number in the current session For this e
2. Copyright 2015 by Ghiocel Predictive Technologies Inc Page 21 of 68 conjunction with the above option i However the ZPA based equivalent static approach is generally overly conservative especially for non symmetric structures but it can also be locally unconservative since it loses the phasing of the seismic loads on the structure The ZPA based approach requires that the user determines calibrated soil springs that need to be included at the foundation support nodes or assume a rigid base The rigid base assumption that was traditionally accepted in the past could be very crude especially for flexible foundations in soft soils as illustrated in the Problem 32 of the Verification Manual ACS SASSI Seismic SSI Analysis Selected Critical Time Steps for Maximum Stresses _ To be Used for Equivalent Static Structural Analysis Computing EEEE Structural Element Stress Structural Sasa O tk Stress Forces pt O O A i Time t1 tj EQS Forces BC Springs EQS Forces BC Displacements EQS Relative Displacements Om ex _ Mesh TT M Refinement y Variable Accuracy C by C Evae Figure 3 ACS SASSI ANSYS Equivalent Static Structural Analysis Using Acceleration Input left Displacement Input right and Mixed Acceleration and Displacement Inputs middle Table 1 describes the different types of equivalent static stress analysis that were implemented based on the SSI approaches illustrated
3. PIPE188 will be displayed as a Beam FLUID80 will be displayed as a Solid Other elements will be ignored by the SUBMODELER Converter and not be included in the model Copyright 2015 by Ghiocel Predictive Technologies Inc Page 5 of 68 To run the SSI analysis for these converted ANSYS models that have different element types than the ACS SASSI element types a new modified HOUSE module called HOUSEFSA is required This HOUSEFSA module is a part of the Option AA capability that is described in Section 4 2 2 SUBMODELER Commands for Checking and Building Complex SSI FEA Models In addition to the PREP commands for building FE models SUBMODELER has many additional commands for checking and building FE models which are described here as follows For reading and writing SSI model files INPUT lt filename gt This command provides the same functionality as the menu path File gt Input used for loading an input text file The input file name should include the full path unless the model name and path have been specified using the MDL command ACTM lt N gt The ACTM command switches the active model to the Model number N The initial Model number when SUBMODELER is started is 0 N can be any integer number MDL lt filename gt lt path gt Create the path for the active Model The path and model name will also be used to define the path and file name used by the WRITE and ANSYS commands DMODEL lt N gt Delete the FE
4. 4 Input the following parameters as shown in Figure 9 a Enter the path of the ANSYS working folder in the group box marked ANSYS Model and Data Input which would be FAANSYS Files in our demonstration b Enter the file name lumped_mass dat that will contain the lumped mass data in the input box marked Lumped Mass Data This file will be generated in Step 6 a by running the input APDL file c Enter the file name get_lumped_mass cmd file that will contain the APDL command that will be used to generate the lumped masses in the input box marked Lumped Mass Data 5 Click the OK button By this action an APDL command file with the file name specified in Step 4 c get_lumped_mass cmd will be generated in ANSYS working folder 6 Run the APDL input file and batch commands a Execute the get lumped mass cmd APDL command file after loading the Coarse ANSYS model in the ANSYS to generate the lumped mass data file This lumped mass data file can now be used to generate seismic forces 7 Input the required parameters as shown in Figure 10 a Enter in the text box next to Path the path name of the ACS SASSI results folder that was prepared in Stage 1 F SSIL_Results b Enter the HOUSE module input file solid_box hou in the text box next to HOUSE Module Input Copyright 2015 by Ghiocel Predictive Technologies Inc Page 38 of 68 c Enter the file name
5. 4 Inthe Path box in the ANSYS Model and Data Input section enter the path of the ANSYS file folder F ANSYS_ Files 5 Inthe Rayleigh Damping Coeff section enter the Raleigh damping coefficients alpha beta for the ANSYS dynamic analysis The input data shown in Figure 21 corresponds roughly to the 5 viscous damping ratio in the low frequency range 6 Inthe ANSYS Output File section enter the name of the file that will contain the ANSYS APDL input commands for the dynamic analysis using the time domain direct integration method This is the file will be loaded in ANSYS 7 Click OK button to generate all the dynamic step load files and file defined in step 6 ANSYS Dynamic Load Converter SASSI Model and Results Input Path F ssi_results HOUSE Module Input solid_box hou Ground Acceleration File ground_acce txt ANSYS Model and Data Input Path F ansys_files Raleigh Damping Coeff Alpha 0 45473e 3 Beta 0 2154 ANSYS Output File ADPL File dyn load cmd Figure 21 ANSYS Dynamic Load Generator Window Copyright 2015 by Ghiocel Predictive Technologies Inc Page 54 of 68 Note During the generation of the dynamic step load files the ANSYS dynamic load generator uses all the relative displacement data files with respect to the free field motion from the SSI analysis results The user should make sure these files have been copied to the ANSYS folder defined in the Path input box of
6. cdb file using the ANSYS command CDWrite DB jobname cdb for later use to create the input file for HOUSEFSA hou file 11 Using the ANSYS APDL macro gen_kmc mac generate the ANSYS model mass stiffness and damping matrices in a binary file format that will be used as input files for the HOUSEFSA module The following parameters are used for the structural model gen kmc 1 After the macro has finished the following files can be found in the ANSYS working directory cooek_r cooeki_r cooem_r cooemi r cooec r coosei r and Node2Equ_Excv map 12 Copy all the ANSYS model generated mass stiffness and damping matrix files into the ACS SASSI working directory 4 2 Using SUBMODELER to Generate the HOUSEFSA Input File Copyright 2015 by Ghiocel Predictive Technologies Inc Page 64 of 68 After the structure and the excavation ANSYS models are saved in the cdb file format they are loaded in the SUBMODELER module and then converted into new ACS SASSI models These new ACS SASSI models might include dummy parameters for the ANSYS elements that are not compatible and therefore not convertible to the ACS SASSI element types It should be noted that if the Option AA is selected then the HOUSEFSA module will not use these dummy parameters and any of the converted elements to build the SSI model matrices but will use the ANSYS model matrices directly as described in the previous section After the structu
7. free field motion and li Nonlinear Analysis foundation can separate from soil material that can behave linear or nonlinear uses as SSI boundary condition inputs the SSI seismic loads on the structure including basement It should be noted that the Linear Analysis LA option requires only the use of the surrounding soil deposit model with relative displacement boundary conditions No structural model is needed The Nonlinear Analysis NA option requires the use of both of the ANSYS structural and soil deposit models with the SSI seismic loads transferred to the structure model Theoretically the NA option can be also applied using the ANSYS dynamic time integration approach but in this case the model size and the mesh refinement of the soil deposit is Copyright 2015 by Ghiocel Predictive Technologies Inc Page 24 of 68 dramatically larger to handle the high frequency wave components transmission and the reflected waves into the infinite soil media space Inclusion of a large size soil model will produce huge computational analysis efforts and therefore is totally impractical for seismic SSI design basis analyses lf dynamic analysis is used then the user has to input the desired boundary conditions for the ANSYS soil deposit model By default no boundary conditions are placed on the lateral surfaces of the soil deposit model ACS SASSI Seismic SSI Analysis Selected Critical Time Steps for Maximum Stresses Was To be Used f
8. one for the structure and one for the excavation volume The steps are as follows Copyright 2015 by Ghiocel Predictive Technologies Inc Page 63 of 68 1 Start ANSYS in the working directory with any job name 2 Load the structure model into ANSYS 3 Check if the ANSYS model meets the model requirements as described earlier compatible element types no D commands damping defined with BETD 4 Write the ANSYS model cdb file using the ANSYS command CDWrite DB jobname cdb for later use to create the input file for HOUSEFSA hou file 5 Using the ANSYS APDL macro gen kmc mac generate the ANSYS model mass stiffness and damping matrices in a binary file format that will be used as input files for the HOUSEFSA module The following parameters are used for the structural model gen kmc 0 After the macro has finished the following files can be found in the ANSYS working directory coosk_r cooski_r coosm_r coosmi r coosc_r coosci_r and Node2Equ_Stru map 6 Save the database in ANSYS If there is no excavation volume skip to step 12 Steps 7 through 11 are only necessary for embedded models with excavation volumes 7 Clear the database and start a new one Set the job name to jobname_excav 8 Load the excavation model into ANSYS 9 Check if the ANSYS model meets the model requirements as described earlier compatible element types no D commands damping defined with BETD 10 Write the ANSYS model
9. 2 Using LOADGEN for ANSYS Equivalent Static Analysis After finishing all the preparation work the user is ready to run the ANSYS load generator To run the LOADGEN module for equivalent static analysis the user needs first open the database and model from the Model menu in the ACS SASSI MAIN then select in the ACS SASSI MAIN menu the option RUN gt ANSYS Eq Static Load There are four options can be selected to generate the load files for ANSYS static analysis The flowchart in Figure 6 shows the basic steps to generate the seismic load files according to the user s selection In the following sections an example will be used to illustrate these steps in more details The paths displayed in the ANSYS Static Load Generator window are F SSI_ Results and F ANSYS files for the SSI result files and the ANSYS input and output files respectively These directories are the ones the user specified in the Stage 1 as described earlier in this section Suppose there are the following files in the folder of F SSI_ Results e Solid_box hou input for the HOUSE module e THD_04 105 00822 THD 04 215 00844 selected displacement frame files at time 4 105 seconds and 4 215 seconds e ACC 04 105 00822 ACC 04 215 00844 selected acceleration frame file at time 4 105 seconds and 4 215 seconds e disp _list txt acc frm list txt input files that include the names of multiple displa
10. ANSYS command in SUBMODELER the new soil model is exported in the ANSYS APDL format If the nonlinear analysis option is selected then contact elements are included for modeling the foundation soil contact interface SUBMODELER generates contact pairs using the ANSYS TARGE170 and CONTA173 elements After loading the SSI model pre file the user should use the SOILMESH command in SUBMODELER to generate the soil deposit model The initial SSI model pre file is by default model number 0 zero The new generated soil deposit model will be the number selected in the first argument of the SOILMESH command The user will need to activate the new model using the ACTM command before the ANSYS ADPL file can be exported using the SUBMODELER ANSYS command Copyright 2015 by Ghiocel Predictive Technologies Inc Page 59 of 68 x Model File Options View T command History x o eee FE FE GE FE FE ee FE ee ee ee ee EEE R R R R R R R R R R R R R R R R R r r THIS FILE WAS WRITTEN BY THE ACS SASSI PREPROCESSOR To reload model type INP lt this file gt in PREP o FE FE RE FE FE FE FE RE RE RE GE R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R r R R r r r r r r r r n n n r n n r n n r r nh Nodes Interaction Nodes Material Table Soil Layer
11. Ghiocel Predictive Technologies Inc Page 42 of 68 Use Multiple File Lists Inputs SASSI Model and Results Input Path Fiissresutts HOUSE Module Input sold boxhou cc Displacement Results NEE lt lt f lt lt Rotatioal Disp Trans Acceleration Results acc 04 105 00822 lt 0 lt lt FT Rotational Accel Mass Data for Intertial Load Ignore for Displacement Mass Type Lumped Mass Master Node Mass Generate Mass Data Figure 11 Acceleration Option with Lumped Mass for Single ANSYS Load file Copyright 2015 by Ghiocel Predictive Technologies Inc Page 43 of 68 Figure 12 Acceleration Option with Lumped Mass for Multiple ANSYS Load Files Copyright 2015 by Ghiocel Predictive Technologies Inc Page 44 of 68 Figure 13 Acceleration Option with Master Node Mass for Single Load File Copyright 2015 by Ghiocel Predictive Technologies Inc Page 45 of 68 ANSYS Static Load Converter Data to Add From ACS SASSI to the ANSYS model C Displacements Acceleration C Displacement and Acceleration C Displacment for Soil Module Use Multiple File Lists Inputs SASSI Model and Results Input Path F ssi_results HOUSE Module Input solid_box hou lt lt Displacement Results Rotatioal Disp Trans Acceleration Results acc_frm_list tet a Rotational Accel ANSYS Model and Data Input F lansys_files Mass Data for Intertial Load Ignore for Displacement Mass Type C
12. MODELING The SUBMODELER module has similar functionalities to the PREP module except the graphical capabilities which are not in SUBMODELER In addition to the PREP commands SUBMODELER has many new commands to check FE modeling and generate both the ANSYS and ACS SASSI models and also convert them back and forth as needed by the user NOTE The fact that SUBMODELER duplicates some of the PREP functionalities is due to our intention to replace the PREP module by the SUBMODELER module in the future The new coming PREP based on the SUBMODELER module will have many additional pre and post processing capabilities than the present PREP module Copyright 2015 by Ghiocel Predictive Technologies Inc Page 2 of 68 SUBMODELER can use all the PREP commands used for building SSI models or selecting SSI analysis options including the AFWRITE command The SUBMODELER also includes new powerful commands for handling and combining multiple ACS SASSI or ANSYS models as described in this section The SUBMODELER is deficient in comparison with the PREP module only on the graphical processing aspects since it has no graphical capabilities at this time SUBMODELER can be launched by selecting RUN gt ANSYS Soil Model Generator from the ACS SASSI MAIN menu As shown in the next sections SUBMODELER is used in Option A to create the surrounding soil deposit ANSYS model or convert ACS SASSI models to ANSYS or vice versa and in Option AA to transfer
13. Table Groups and Elements Masses Model Options Analysis Options Frequencies INPUT FILE REACHED EOF INPUT SWITCHED TO KEYBOARD soilmesh 1 07 07 20 20 0 0 5 Soil Mesh created successfully actm 1 Active Model Switched to number 1 ansys box_soil C ACSV2Z30A Wrote C ACSVZ230A box_soil inp Successfully Figure 24 Application of the SUBMODELER Module SOILMESH ACTM and ANSYS Commands to Generate an ANSYS Surrounding Soil Model Demo 6 illustrates in detail the use of the above commands for generating a soil deposit model Copyright 2015 by Ghiocel Predictive Technologies Inc Page 60 of 68 4 OPTION AA OR ADVANCED ANSYS The Option AA or Option Advanced ANSYS of the ACS SASSI ANSYS integration capability enables the use of an ANSYS structural model for SSI analysis directly without the need for converting the structural model to ACS SASSI The ANSYS structural stiffness mass and damping matrices are directly used by ACS SASSI for SSI analysis The SSI relative displacements absolute accelerations and response spectra for the ANSYS structural FEA model are fully computed within the ACS SASSI software Option A should be used to transfer the SSI response motions at all time steps or selected critical steps as boundary conditions for the ANSYS superstructure model for computing structural stresses Option AA works with the fast solver implementation only The Option AA was implemented by modifying the HOUSE
14. This command fixes the rotational degrees of freedom of all the nodes that are only connected to Springs and Springs Solid node connections If the node is only connected to a Spring the unconstrained degrees of freedom are determined by the spring stiffness If the node is connected to Springs and Solids the rotational degrees of freedom are determined by the Springs rotational stiffness FIXSHLROT lt Stiff gt This command applies rotational soft springs to all nodes that are only connected to coplanar shells The overall spring stiffness is determined by the stiffness argument of the command and applied along the normal shell s plane lt Stiff gt Stiffness of the soft springs added to shells to remove the shell drilling rotation singularities default stiffness value is 10 WARNING The above FIXROT and FIXSHLROT commands are HIGHLY RECOMMENDED to be used for ACS SASSI FE shell models that have shells that are oblique with respect to the Copyright 2015 by Ghiocel Predictive Technologies Inc Page 10 of 68 global coordinate system planes These oblique shell elements can produce numerically unstable SSI models The use of FIXROT FIXSHLROT ensures that no numerical singularities could be produced by the shell drilling equations The use of FIXROT FIXSHLROT is highly recommended especially if large size SSI models are run with the fast solver SSI modules Benchmark results obtained against ANSYS for various fixed base models have indica
15. approaches are demonstrated in the Verification Manual Problem 32 This problem includes comparisons of the ACS SASSI and ANSYS displacements and stress results for the fixed base model the surface SSI model and the deeply embedded SSI model lt should be noted that for the quasi static or equivalent static analysis the ANSYS structural stresses and the ACS SASSI structural stresses matching is practically perfect for identical structural FEA models i e when the ANSYS model is obtained using the ACS SASSI automatic converters However for the ANSYS dynamic SSI analysis option the ANSYS and ACS SASSI stresses could be significantly different due to the fact that the mass and damping matrices are different and the numerical solution algorithms for solving equations of motion are different WARNING If the ANSYS dynamic SSI analysis option is selected then the differences between ANSYS and ACS SASSI SSI results due to different mass and damping matrix formulations and numerical solution methods as the direct time integration integration method in ANSYS and the complex frequency convolution method in ACS SASSI have to be evaluated by the user before the final SSI production runs are started WARNING For embedded structures the user should compute kinematic SSI structural accelerations for zero mass structure and then use them to define the translational and rotational rigid body acceleration fields as required to define the seismic load
16. best use the ACS SASSI ANSYS interface via Options A and AA The Option A or Option ANSYS of the ACS SASSI ANSYS interfacing capability is based on an integrated two step SSI approach in which the 1st step is the overall SSI or SSSI analysis using ACS SASSI and the 2nd step is the detailed structural stress analysis using ANSYS with the input boundary conditions defined by the SSI responses computed with ACS SASSI The LOADGEN module that is a part of the ACS SASSI MAIN module GUI is used to transfer the data from the ACS SASSI results database to the ANSYS input files Option A works with both the standard solver and the fast solver implementations The Option AA or Option Advanced ANSYS of the ACS SASSI ANSYS integration capability consists of using directly an ANSYS structural model for SSI analysis without the need for converting the structural model to ACS SASSI The ANSYS structural stiffness mass and damping matrices are used directly by ACS SASSI for SSI analysis The SSI relative displacements absolute accelerations and response spectra computed for the ANSYS structural FEA model are obtained using the ACS SASSI software The Option A should be used to transfer the SSI response motions at all or selected critical steps as input boundary conditions for the ANSYS superstructure model only for computing structural stresses Option AA works with the fast solver implementation only 2 USING THE SUBMODELER MODULE FOR ACS SASSI AND ANSYS FE
17. fast solver module and developing a new auxiliary program called SSI_ANSYS exe To make things simple the new auxiliary program is wrapped inside an ANSYS APDL input file that will be run in ANSYS to produce the structural stiffness mass and damping of the structure For embedded SSI models both the structure FEA model and the excavated soil FEA model need to be developed in ANSYS These ANSYS models are then loaded in the ACS SASSI SUBMODELER module and merged into a single SSI model For surface SSI models only the structure FEA model needs to be generated in ANSYS and transferred to ACS SASSI using SUBMODELER After the SSI model is created in SUBMODELER including both the structure and excavated soil FEA models for embedded models and only structure for surface models it can be saved in the pre format using the WRITE command and in the hou input format for the HOUSE module using the AFWRITE command SUBMODELER can be also used to define the interaction nodes The modified HOUSE fast solver module for Option AA is called HOUSEFSA This modified HOUSE module is capable of reading the hou input file created by SUBMODELER even ANSYS element types that are incompatible with ACS SASSI element types are used WARNING It should be noted that the ACS SASSI SSI model saved in pre or hou formats it might include features from the ANSYS that are not compatible with the ACS SASSI finite element types For example if the PIPE or LINK element
18. fills a pool with solid fluid elements including a spring pool water wall interface and the surface areas of the interface using shells The pool is filled using an algorithm used in the EXCAV command where the floor of the pool and the wall Z levels are used to create group solid elements to fill the volume The interface of the pool wall water are connected by a set of springs with the stiffness of these springs determined by the user The user should create a FE model of the pool to be filled before using this command The pool FE model should only contain the walls and floor of a single pool to be filled The walls and floor must be made of either shells or solids lt Stiff gt Stiffness of the water wall spring interface parallel to the normal Default 105 lt Sensitivity gt allowable tolerance variation in Z coordinate on the same Z level Default 0 lt EmptyLevels gt Number of Z levels starting at the highest level not to be filled with water Default is 0 that is pool is entirely filled with water lt ShellArea gt This parameter should be skipped by leaving blank its field lt offset gt the user defined starting node number for numbering of the pool elements This number should be greater than or equal to last node number from the original FE model if the user intends to import the water and spring group back into the original model If the offset is less than or equal to 0 the pool wall node number maximum will be used Def
19. forcing function inputs for the ANSYS dynamic analysis In addition the foundation relative displacements with respect to the free field motions shall be computed for all the excavation levels Copyright 2015 by Ghiocel Predictive Technologies Inc Page 19 of 68 3 3 SSI Methodology for Two Step Approach Before using the ACS SASSI ANSYS integration capability the user must convert the ACS SASSI structural model to an ANSYS structural model using the ACS SASSI converter The converter produces an ANSYS model that is identical with the ACS SASSI structural model This will be referred to in this documentation as the Coarse ANSYS model WARNING The user has to make sure that this Coarse ANSYS model includes no D nodal constrains This is required since this ANSYS model will be used to generate the mass matrix data via modal analysis option The Coarse ANSYS model converted from ACS SASSI can be used as a starting point for building a Detailed ANSYS structural model by using either the EREFINE command for SHELL models or other options in ANSYS The user can also develop a Detailed ANSYS structural model directly in ANSYS not by using the converted ACS SASSI model The Detailed ANSYS does not need to have the node or element numbering or even the geometry configuration of the Coarse ANSYS model that is identical configuration with the SSI model However we recommend as a good practice to include all the nodal points from the
20. format In the latter case the ACS SASSI excavation volume part of the embedded SSI models is automatically deleted during the conversion to the ANSYS model The model conversions are done efficiently via the command line in SUBMODELER The LOADGEN module uses a simple GUI window dialog to transfer the seismic SSI boundary conditions the seismic loading and relative displacements at the foundation soil interface from the ACS SASSI SSI result database acc and thd frames to the ANSYS structural model via a ANSYS APDL command file This can be done either for a single time step or all time steps or selected critical time steps The SUBMODELER module similar to the LOADGEN module uses a simple GUI window dialog to generate a new surrounding soil FE submodel in the ANSYS APDL input format based on the ACS SASSI SSI model embedment geometry The LOADGEN module is then used to transfer the SSI relative displacements at the interaction nodes defined at the foundation interface with respect to the free field motion and the nodal seismic forces for all active dofs at the selected time steps 3 1 SSI Modeling Issues The second step analysis performed in ANSYS can be either i a quasi static or equivalent static stress analysis performed for the selected critical time steps or ii a dynamic stress analysis using the direct integration approach The ANSYS equivalent static analysis option is applied at all or selected critical time steps so th
21. in Figure 3 Of these approaches the mixed approach using both the SSI acceleration and displacement boundary condition as inputs shown in the middle of Figure 3 is recommended as the best approach This approach is particularly useful when the ANSYS equivalent static model is much more refined than the SSI model and or when improved element types for computing stresses and or local structural nonlinearities are included Copyright 2015 by Ghiocel Predictive Technologies Inc Page 22 of 68 Equivalent Static EQS SSI Structural Response Boundary Conditions Computed Stress Comments Approaches Quantities Used Loaded DOFs Accuracy Equivalent Static Inertial Maximum Accelerations All Dynamic Structural Variable from reasonable to Only one static analysis Forces Maximum Values 7PA DOFs crude Seismic load phasing Soil spring evaluation is Automatic export from ACS ANSYS master node at any given time is lost The difficult inconsistent SASSI to ANSYS except the masses are computed results are globally Affected by the soil spring soil springs to be computed by automatically and then conservative but locally evaluation acc T a Ma could be unconservative Some local nonlinearities or the user used for inertia force leulati especially for asymmetric local configuration changes s structures and flexible could be considered foundation structures Equivalent Static Inertial Accelerations at t tk All Dynami
22. in the LOADGEN GUI The name of the file containing the list of frame files should be input into the appropriate box for either Displacement option or Acceleration option If the Displacement and Acceleration option is used then two list files must be created for both acceleration and displacement frames at selected times Below is an example of a displacement list file disp _list txt This file will be used to create input BCs for ANSYS analysis using the two selected relative displacement frames 2 THD_04 105_ 00822 E THD_04 215 00844 F Step 2 Create a folder to save ANSYS model and input load files In this second step the user creates a folder where the ANSYS model and input load files produced from LOADGEN will be saved This folder called F ANSYS_ Files in this example should contain the files listed below Please note that it will be necessary to use two ANSYS models for this step A copy of the original ANSYS model should be modified to remove all displacement boundary conditions Any beam releases should be removed as well to ensure compatibility with using the LUMPM option This secondary model will only be used to generate the nodal mass file to be used with LOADGEN The original model will still be used for the ANSYS analysis The files contained in the ANSYS working folder described above are as follows Copyright 2015 by Ghiocel Predictive Technologies Inc Page 31 of 68 1 The Coarse ANSYS model th
23. model and the user defined cut data are used to create the new model submodel The user also has the option to create a thick shell model using the solid option The thick shells should be used ONLY for visualization because the geometry generation algorithm has no way to test if the newly formed solids intersect each other lt cutnum gt Number of the cut to be used lt dest gt number of the destination model lt solid gt Turn all shells in to solid elements if solid gt 1 Default solid 1 CSECT lt model gt lt cutnum gt lt X gt lt Y gt lt Z gt lt normalX gt lt normalY gt lt normalZ gt The command creates a new section cut model submodel based on the section cut data defined by the user The user must define the section cut to be used and the destination model of the cross section as defined by the first two arguments The other arguments are used to define an infinite plane by a point on the plane and the orientation of the normal to the plane The SUBMODELER will then take a cross section of all the elements in the cut at the infinite plane The elements of the cross section will be expanded to a unit thickness so that the user can visualize the cross sectional model This model can then be used to find the section cut forces and moments at the center of gravity of the section cut lt model gt The section cut model number lt cutnum gt section cut number lt pointX gt x coordinate of the s
24. model number N ANSYS lt filename gt lt path gt The ANSYS command writes the model in an ANSYS APDL input file extension inp ANSYS lt filename gt lt path gt must be used if the active model name and path have not yet been specified using the MDL command If the model name and path have been defined then no arguments are necessary and the ADPL file will be saved to the active model directory WRITE lt filename gt lt path gt The WRITE command writes the model in an ACS SASSI PREP input file extension pre WRITE lt filename gt lt path gt must be used if the active model name and path have not yet been specified using the MDL command If the model name and path have been defined then no arguments are necessary and the ADPL file will be saved to the active model directory For building SSI models ANSYSREFORMAT lt Org gt lt Map gt creates an ACS SASSI model input that has beam end releases compatible with ANSYS model input structure This command takes an ACS SASSI model and regroups the beam elements based on their set of end releases so that the beam end Copyright 2015 by Ghiocel Predictive Technologies Inc Page 6 of 68 releases can be translated into an ANSYS ADPL format correctly This command should be used with an empty active model The user specifies which model should to be converted lt Org gt Model number of the model to be reformatted lt Map gt A mapping file that indicates the co
25. moment histories will then be written to the lt outfile gt The lt inpfile gt should have the same format with the PREP animation files such as the thani extension file lt inpfile gt full path of the input file that contains the list of the ess frame files lt cutnum gt The cut to be used lt pointX gt x coordinate of the selected point on the plane lt pointY gt y coordinate of the selected point on the plane lt pointZ gt z coordinate of the selected point on the plane lt normalX gt x component of the normal vector of the selected cut plane in global coordinates lt normalY gt y component of the normal vector of the selected cut plane in global coordinates lt normalZ gt z component of the normal vector of the selected cut plane in global coordinates lt positiveX gt x component of the local system orientation for X axis direction in global coordinates positive Y gt y component of the local system orientation for X axis direction in global coordinates lt positiveZ gt z component of the local system orientation for X axis direction in global coordinates lt sysno gt the local system number where the local system will be stored lt outfile gt full path of the output file for the section cut force and moment histories For the Option AA analysis when ANSYS FLUID80 elements are used FILLPOOL Stiff Sensitivity EmptyLevels ShellArea Offset stiff2 This command
26. planes and have no connection that provides stiffness for the shell in plane rotations The FIXROT command fixes rotations by using the D command to fix rotations described above For the shell elements that are not parallel to a global coordinate system planes the FIXROT command automatically adds low stiffness in plane rotational springs to each node of the shells rotations around the normal to the shell planes The user can control the rotational spring stiffness using the lt stiff gt parameter of the command By default the rotational spring stiffness is 10 The user can change the lt stiff gt parameter values in the updated pre file as needed if more or less local stiffness is desired in particular sections of the model To do this the user should edit the values of the SC commands in the pre file The stiff parameter 10 is an appropriate value for typical nuclear structure models that consist of concrete shells for which the shell bending stiffnesses are at least several thousand times larger if defined in kips ft rad The recommendation based on FE theory is that the stiff parameter should be less than 10 of the shell element bending stiffness The user will need to use the WRITE command to save all the FIXROT command fixes in an updated pre input file that then can be reviewed by the user FIXSLDROT This command fixes the rotational degrees of freedom of all the nodes that are only connected to Solid elements FIXSPRROT
27. that contains the master nodal mass data master _mass dat This file will be created by ANSYS in Step 9 which will be used for calculating the seismic forces for the Detailed ANSYS model d Enter the file name that contains the APDL commands to get the master node mass data get master mass cmd This file will be used to generate the master nodal mass data in the input box marked with APDL File This file will be used to generate master mass data in Step 9 8 Click the OK button to generate the APDL command file with the file specified in step 7 d get master mass cmd 9 Generate the reduced nodal mass data for the Detailed ANSYS model for the selected master nodes that are automatically selected to be all the nodes used to define the Coarse ANSYS model The user must execute the APDL command file get_master_mass cmd after loading ANSYS refined model in the ANSYS The master mass data file master mass dat will now be generated This file will be used in the seismic force calculations in related sections As mentioned earlier the nodal mass data calculation procedure requires the ANSYS model has no displacement constraints and is able to be used for modal analysis with option LUMPM 1 If the ANSYS model has any released nodal degrees of freedom ANSYS will not be able to perform a modal analysis Therefore the user must remove the nodal degree of freedom releases from the ANSYS model This is a l
28. that means just 3 translation acceleration will be used in the ANSYS dynamic analysis if NComp 6 that means the both translation acceleration and rotation acceleration data will be used in the ANSYS dynamic analysis Xcg Ycg Zcg the rotation center of rotation acceleration in the global coordinate system Line 2 ax ay az if NComp 3 or Ax ay az ax ay az if NComp 6 where ax ay az are the translation accelerations of three directions in global coordinate system ax ay a are the rotation accelerations around the three axes of the global coordinate system Copyright 2015 by Ghiocel Predictive Technologies Inc Page 55 of 68 0 0050 3 30 0 40 0 30 0 0 0000 0 0000 0 0000 0 0000 0 0000 0 0001 0 0000 0 0000 0 0000 0 0000 0 0000 0 0001 0 0000 0 0000 0 0000 0 0000 0 0000 0 0001 Figure 22 File Format of the Ground Acceleration File with 3 DOF 0 0050 6 30 0 40 0 30 0 0 0000 0 0000 0 0000 0 0000 0 0000 0 0001 0 0001 0 0081 0 0091 0 0104 0 0121 0 0141 0 0000 0 0000 0 0000 0 0000 0 0000 0 0001 0 0001 0 0081 0 0091 0 0104 0 0121 0 0141 0 0000 0 0000 0 0000 0 0000 0 0000 0 0001 0 0001 0 0081 0 0091 0 0104 0 0121 0 0141 Figure 23 File Format of the Ground Acceleration File with 6 DOF Copyright 2015 by Ghiocel Predictive Technologies Inc Page 56 of 68 3 5 ANSYS Equivalent Static Analysis for Founda
29. ACS SASSLANSYS Integration Cap ability Version 3 0 Options A and AA An Advanced Computational Software for 3D Dynamic Analysis Including Soil Structure Interaction User Manual Revision 2 t 7 March 31 2015 Ghiocel Predictive Technologies Inc 4 South Main St 3 Floor Pittsford NY 14534 USA Phone 585 641 0379 Fax 585 586 4672 E mail acs sassi ghiocel tech com ANSYS is a trademark of ANSYS Inc DISCLAIMER GHIOCEL PREDICTIVE TECHNOLOGIES INC DOES NOT WARRANT THE OPERATION OF THE ACS SASSI VERSION 3 0 PROGRAM WILL BE UNINTERUPTED OR ERROR FREE GHIOCEL PREDICTIVE TECHNOLOGIES INC MAKES NO REPRESENTATIONS OR WARRANTIES EXPRESS OR IMPLIED INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE Ghiocel Predictive Technologies Inc in any case shall not be liable for any costs damages fees or other liability nor for any direct indirect special incidental or consequential damages including loss of profits with respect to any claim by LICENSEE or any third party on account of or arising from this License Agreement or use the ACS SASSI Version 3 0 program The ACS SASSI Version 3 0 baseline code using the standard skyline solver has been extensively verified tested and used for seismic 3D soil structure interaction models up to 25 000 nodes including up to 5 000 interaction nodes However for 20 000 node or Sl
30. ANSYS model information to ACS SASSI to perform the SSI analysis using the ANSYS structural model directly with no need for conversion to ACS SASSI SUBMODELER has also a set of commands that permit to the user to compute the Section cut forces and moments For example the user can create plane section cuts for selected submodels such as a concrete shearwall and then compute the cross sectional forces and moments for different section cuts at different floor levels For details please see Demo 8 and Problem 47 in the Verification Manual 2 1 SUBMODELER Converters for ANSYS Models The SUBMODELER also has a powerful capability to convert models from ANSYS cdb file to ACS SASSI models The SUBMODELER Converter has much fewer limitations than the MAIN Converter The ANSYS model conversion limitations for MAIN Converter are described in the MAIN User Manual In this section only the SUBMODELER Converter limitations are described The SUBMODELER Converter is capable of converting ANSYS Version 13 14 models that might have element types that are not fully compatible with the ACS SASSI element types The SUMBMODELER Converter can handle the following element types i SOLID element types SOLID45 and SOLID185 ii SHELL element types SHELL63 and SHELL181 iv BEAM element types BEAM44 and BEAM188 v PIPE element types PIPE188 vi COMBIN element types COMBIN14 vii Couple nodes CP command viii Constraint equations CE commands ix Multip
31. CS SASSI SSI analysis result database lt should be noted that the SSI nodal forces and nodal displacements are transmitted to the ANSYS model based on the structure node coordinates The nodal seismic load and or relative displacements with respect to the free field control motion from the SSI analysis are applied at the same node locations within the Detailed ANSYS model The nodal acceleration response data is converted to the nodal seismic forces by multiplying them with nodal masses The displacement boundary conditions and the seismic forces are generated in the ANSYS APDL format input files so that the user can apply them directly to ANSYS using the command INPUT The user has two options for defining the nodal seismic forces for the Detailed ANSYS model based on the mass matrix formulations 1 Lumped Mass matrix of the Coarse ANSYS model that is identical to the SSI model this ANSYS coarse model can be obtained by the user using the new ACS SASSI PREP converter from ACS SASSI to ANSYS and 2 Reduced Mass matrix of the Detailed ANSYS model using a Guyan reduction of the mass matrix of the Detailed ANSYS model assuming as masters all the active degrees of freedom of the Coarse ANSYS model 3 4 1 Requirements and Limitations In this section we describe the use of the ANSYS load generator or LOADGEN module included in the MAIN GUI menu to transfer the ACS SASSI SSI analysis result data as input boundary conditions
32. Coarse ANSYS model in the Detailed ANSYS model The seismic loads and relative displacements are transferred from ACS SASSI to ANSYS only based on the node coordinate information and the applied loads and BCs are placed at the closest coordinate from the nodes in the Detailed ANSYS model The LOADGEN module ensures the automatic transfer of the SSI responses in terms of nodal seismic forces based on the node accelerations computed with MOTION and nodal relative displacements with respect to free field motion computed with RELDISP to the ANSYS model The seismic SSI boundary conditions nodal seismic loads and or nodal relative displacements from the ACS SASSI structural model are automatically transferred to the refined Detailed ANSYS structural Foundation displacements can be also transferred to the surrounding soil submodel The nodal coordinates of the Coarse ANSYS model are used to identify the node locations of the seismic loads and relative displacements in the Detailed ANSYS model For computing the seismic loads on the Detailed ANSYS model user has two options i Use the lumped mass matrix of the Coarse ANSYS model or li Use the reduced mass matrix obtained from the Detailed ANSYS model via the ANSYS Guyan reduction for computing the structural seismic forces nodal masses multiplied by the nodal accelerations If the lumped mass matrix option i is used then the Coarse ANSYS model needs to be generated using the SUBMODELER If
33. ED The RMVUNUSED Command checks elements and interaction nodes in the current model to see which nodes are being used All unused non interaction nodes will be removed from the model This command does not compress node numbers or change element node connections The command should be used in conjunction with NCOM to compress the node list of a complete model INTGEN lt type gt skip automatically generates interaction nodes for different substructuring approaches FV FI FSIN SM FI EVBN MSM Surface model and Fast FV The excavation volume must be explicitly defined by the ETYPE command for options 1 3 If the ETYPE of the elements is left to the default values this command will not work The lt type gt argument is the type of iteration node generation to be used 1 Embedded Foundation Flexible Volume FV Copyright 2015 by Ghiocel Predictive Technologies Inc Page 8 of 68 2 Embedded Foundation Flexible Interface with Excavation Volume Boundary Nodes denoted FI EVBN or Modified Subtraction Method MSM 3 Embedded Foundation Flexible Interface with Foundation Soil Interface Nodes denoted FI FSIN or Subtraction Method SM 4 Surface Foundation interaction nodes are only at the ground surface level 5 Embedded Foundation Fast FV including multiple layers of internal interaction nodes The skip argument is only necessary when using type 5 Type 5 gives the option to include intermediate layers of interactio
34. Lumped Mass Master Node Mass Generate Mass Data For Lumped Mass Lumped Mass Data lumped mass dat For Master Mass Master Node Mass master_mass dat ANSYS Output File ADPL File acc_master_apdl list txt Figure 14 Acceleration Option with Master Node Mass and Multiple ANSYS Load files It should be noted that for the Acceleration option the user needs to apply the proper stiffness constraints at the foundation boundary nodes usually by static soil springs placed at support nodes However the evaluation of these soil springs could be challenging especially when the foundation is embedded or with an arbitrary shape A much more accurate solution for the foundation boundary conditions is to provide the relative displacements at support nodes with respect to free field input motion at selected time steps Displacement and Acceleration Option The Displacement and Acceleration option provides an appropriate set of boundary conditions for equivalent static analyses This option is designed to generate a mixed boundary condition Copyright 2015 by Ghiocel Predictive Technologies Inc Page 46 of 68 load file This option will generate equivalent static relative displacement boundary conditions at the support nodes SSI interaction nodes of the ACS SASSI SSI model at the soil foundation interface and the equivalent static seismic forces at all structural nodes The inputs depend on the selected nodal mass data o
35. MODELER 4 3 Running the HOUSEFSA Module It should be noted that during the HOUSEFSA module execution the extension name of input hou will be changed to a new extension name hounew This is due to the fact that during the HOUSEFSA module run the model node numbering is automatically optimized to provide best numerical conditioning storage use and computational speed Thus the new final input filename for the HOUSEFSA module input is modelname hounew filename not the initial modelname hou filename generated using SUBMODELER HOUSEFSA also produces a modelname map file that provides the node mapping between the original SSI model created by SUBMODELER and the new optimized SSI model produced by HOUSEFSA It should be noted that the FILE4 or modelname n4 file and the COOSK and COOSM files produced by HOUSEFSA correspond to the optimized input model not the original input model Thus the user should use the node mapping provided in this modelname map file to extract the SSI analysis results at the correct locations when using the MOTION and RELDISP modules The output node numbers will correspond to the node numbers of the optimized SSI model included in the modelname hounew file The Demo 7 problem illustrates in detail two examples of using the ACS SASSI ANSYS Interface in Option AA for a surface model and an embedded model Copyright 2015 by Ghiocel Predictive Technologies Inc Page 68 o
36. SASS Model and Results Input section For embedded foundations these relative displacements must be computed at different depth levels with respect to the free field motion at the same depth levels This is required since the free field motions at different depths are different than the control motion which is defined at a single location Only for surface foundations under vertically propagating waves should these relative displacements be computed only with respect to the control motion After all files were generated the user can perform the ANSYS dynamic analysis using the ANPUT command The Ground Acceleration File defines the kinematic SSI response rigid body acceleration fields computed during the SSI analysis The acceleration history data is identical with ground acceleration only for surface foundations under vertically propagating waves The file format is shown in Figures 22 and 23 The first line is the control data the other next lines starting from the second line to the end of the file contain the acceleration time history data for all six degree of freedom in space Acceleration data should be input as units of g LOADGEN will use the acceleration due to gravity from house to convert the ground acceleration into consistent units for ANSYS Line 1 At NComp Xcg Ycg Zcg At the time step size of the acceleration time history NComp the number of acceleration components NComp can be 3 or 6 only if NComp s
37. SYS is problematic for BEAM44 when the BEAM end releases are different from beam element to beam element inside of the group of the BEAM elements This is because ANSYS does not accept variations in beam releases from element to element for the same ETYPE command that is equivalent to ACS SASSI Group commands In this case the structure of the ACS SASSI model and ANSYS model are not compatible For these situations we suggest use of the ANSYSREFORMAT command that regroups all the beam elements into groups that have a common set of end releases and creates a new ACS SASSI model that is compatible with ANSYS model WARNING The SUBMODELER Converter will convert the ANSYS model in ACS SASS format so that it can be displayed in the PREP but this model will be flagged by SUBMODELER and the hou file that the AFWRITE command generates will not be runnable using the standard HOUSE module If the SSI model isn t runnable with standard HOUSE module the user will receive a warning when the file is converted The list of elements types below are the additional element types that can be converted in the ACS SASSI PREP format for graphical processing There are no limitations on these elements because only element node connections need to be translated for display The list below specifies the element type from ANSYS and the element type used to represent it in the ACS SASSI model TRUSS180 will be displayed as a Beam MPC184 will be displayed as a Spring
38. aded in the following order 1 Input structural model 2 Input load data 3 Input soil model Loading the inputs in this order will ensure that none of the seismic loads are incorrectly placed on the soil elements seismic loads are placed in the nearest neighbor nodes 4 As with a linear soil pressure analysis the user should apply appropriate boundary conditions on the soil model boundaries SUBMODELER automatically fixes all degrees of freedom at the bottom of the soil deposit No boundary conditions are imposed on lateral surface of the soil model This avoids producing non uniform displacement and stresses under gravity loads that are included in the nonlinear seismic soil pressure analysis 5 If contact elements are generated the user must input the number of the real constant to be used for the contact pair This is the last argument in the SOILMESH command in SUBMODELER The user should select a number that will not be used by another constant set for beams shells masses springs etc Using a large number will usually prevent any overlap in real constant numbers 6 The values for the real constants associated with the contact surface pair needs to be defined by the user It is recommended that the user reads the ANSYS documentation for contact analysis prior to attempting a nonlinear soil pressure analysis due to the complexities of the analysis Demo 6 includes recommended values for the real constant Copyright 2015 by Ghi
39. apply the equivalent static seismic forces on the structure the user must generate the nodal mass data first In order to generate the nodal mass data for inertial forces the user should follow these steps shown below 1 Check the Generate Mass Data box in the Mass Data for Inertia Load section After checking that box the program enters the nodal mass data generation mode regardless of what function the user chooses in the selection box With this box checked no seismic load Copyright 2015 by Ghiocel Predictive Technologies Inc Page 37 of 68 data is produced Only the ANSYS APDL command file for generating nodal mass data will be generated This file will be used later to generate mass data in given file for calculating seismic force loads on structure 2 Select the appropriate nodal mass data type radio button based on your plan and prepared work There are two types of mass data for equivalent static seismic forces The Lumped Mass option will calculate the nodal mass data from the Coarse ANSYS model with LUMPM 1 setting The Master Node Mass option will calculate the nodal mass data from the Detailed ANSYS model at the master nodes The lumped mass option is selected by default The user interface is shown in Figures 9 and 10 for Lumped Mass and Master Node Mass respectively 3 Ifthe user selects Lumped Mass then go to Step 4 If Master Node Mass is selected then the go to Step 7
40. assless structure or ii the absolute displacement histories at all foundation soil Support nodes The foundation flexibility SSI effects is captured through the displacement histories at the foundation soil interface nodes WARNING Due to the differences in the dynamic modeling in ANSYS and ACS SASSI i e different formulations for the mass and damping matrices and different numerical techniques for solving the differential equations of motion for SSI system we recommend a preliminary comparative ACS SASSI ANSYS stress analysis using identical FEA models in the two codes i e the Coarse ANSYS model that is obtained by converting from the ACS SASSI model Such a preliminary comparison between Coarse ANSYS model results and ACS SASSI results is necessary to validate the ANSYS dynamic model including the Rayleigh damping modeling Copyright 2015 by Ghiocel Predictive Technologies Inc Page 23 of 68 against ACS SASSI results After the ANSYS model validation is passed only then for the final stress analyses the Detailed ANSYS model can be used instead of the Coarse ANSYS model 3 3 3 ANSYS Equivalent Static Seismic Soil Pressure SSI Analyses Using the ACS SASSI ANSYS integration Option A capability the user can efficiently and reasonably accurately compute the seismic soil pressure on the embedded foundation walls and base slabs Using ANSYS equivalent static analysis the seismic soil pressures can be computed for the critical time ste
41. at is converted from the ACS SASSI SSI model using the Export to ANSYS menu selection or ANSYS command in SUBMODELER The model converter translates the ACS SASSI structural model to an ANSYS APDL file with the extension inp This text file is found in the ACS SASSI working folder The user should copy the file to the ANSYS working folder called F AANSYS_ Files The Coarse ANSYS model db file is created by using the INPUT command in ANSYS and is saved as a db file If the user plans to use Lumped mass to do the equivalent static analysis a Coarse ANSYS model for generating lumped mass data should prepared by the following steps 1 delete all displacement BCs in the generated Coarse ANSYS model 2 make sure this model is able to do modal analysis 3 save as ANSYS model for generating Lumped mass data 2 If the user plans to use Master Mass for the ANSYS analysis he should also prepare the Detailed ANSYS model for generating mass matrix data for the reduced dynamic model that corresponds to the master nodes defined by all nodes of the Coarse ANSYS model by the following step 2 1 Copy the Detailed ANSYS model in the folder F ANSYS_ Files 2 Load this model into ANSYS 3 Delete all the displacement BCs 4 Make sure the model is able to do modal analysis 5 Save it for generating mass data at the master nodes 3 If the user wishes to generate multiple load files in a single run then the frame name list f
42. at the seismic loading phasing and foundation deformations are correctly included It should be noted that the ACS SASSI ANSYS equivalent static stress analyses at selected time steps are more accurate than those computed using the traditional ZPA based approach that computes the seismic equivalent static forces based structural the ZPA values However for the users convenience the traditional ZPA based approach can be also applied using the ACS SASSI ANSYS interfacing capability For seismic soil pressure SSI analyses both the LOADGEN and SUBMODELER modules are used as explained in this manual Both linear elastic analyses and nonlinear equivalent static analyses including nonlinear soil and foundation soil separation effects can be considered The ANSYS dynamic time domain direct integration analysis uses all time steps The major benefit of the time domain dynamic ANSYS analysis is that is greatly reduces the computational requirements of a direct ANSYS SSI analysis approach by eliminating the need of including additional surrounding soil elements in the SSI FE model Instead the SSI boundary conditions corresponding to the foundation absolute displacements could be applied at the foundation soil Copyright 2015 by Ghiocel Predictive Technologies Inc Page 18 of 68 interface nodes of the ANSYS To get the absolute displacements at the support nodes the computed SSI relative displacements has to be added with the free field absolu
43. ault 1 an error will occur for any positive number that is less than the pool wall node number maximum lt stiff2 gt Stiffness of wall spring interface in tangential direction to the wall Default 0 Copyright 2015 by Ghiocel Predictive Technologies Inc Page 15 of 68 3 OPTION A OR ANSYS The Option A or Option ANSYS ACS SASSI ANSYS interfacing capability is based on an integrated two step SSI approach in which the 1st step is the overall SSI or SSSI analysis using the ACS SASSI model and the 2nd step is the detailed structural stress analysis using the ANSYS model with the input boundary conditions defined by the SSI responses The LOADGEN module that is a part of the ACS SASSI MAIN module GUI is used to automatically transfer the data from the ACS SASSI result database to the ANSYS input files The 2nd step using ANSYS has two distinct functionalities i Perform structural stress analysis using refined ANSYS FE structural models with detailed meshes eventually including enhanced element types non linear material and plasticity effects contact and gap elements and li Compute seismic soil pressure on basement walls and slabs including soil material plasticity foundation soil separation and sliding using refined ANSYS FE soil deposit models The 1st functionality involves creating a more detailed FE model in ANSYS that corresponds to the coarse ACS SASSI structural model while the second funct
44. c Structural Reasonable especially if Few to several static Forces at t tk DOFs soil springs are well analyses Affected by the Automatic export from ACS Same note as above selected Include seismic soil spring evaluation SASSI to ANSYS except the load phasing accuracy Some local nonlinearities or local configuration changes could soil springs to be computed by the user Equivalent Static Displacements at t tk Theoretically Exact Displacements at t tk i i analyses Could be used for Automatic export from ACS submodeling for selected SASSI to ANSYS User just clicks Equivalent Static Forces and Accelerations and Dynamic Structural Theoretically Exact Displacements at t tk Displacements at t tk DOF s for Accelerations analyses Some local Automatic export from ACS and Soil Coupling DOFs nonlinearities or local SASSI to ANSYS User just for displacements configuration changes could clicks be considered Table 1 ANSYS Equivalent Static Seismic Stress Analyses Including SSI Effects 3 3 2 ANSYS Dynamic Structural Stress SSI Analyses Through the ACS SASSI ANSYS integration capability ANSYS can be used to perform an efficient dynamic analysis in the second analysis step using either the Coarse or the Detailed ANSYS model In this case the seismic load can be defined by either i the kinematic SSI forces on the structure that are introduced by the SSI translational and rotational rigid body acceleration history of the m
45. cement data files and acceleration data files respectively These name list files are required only if Use Multiple File List Input box is selected They are prepared in Stage 1 described earlier in his section And there are the following files prepared in the folder of F ANSYS files e Solid_box inp the ANSYS APDL input file automatically generated by the ACS SASSI PREP converter using the menu selection Convert to ANSYS e solid _box db the Coarse ANSYS model identical with SSI model geometrically database produced by ANSYS for lumped mass data option Copyright 2015 by Ghiocel Predictive Technologies Inc Page 33 of 68 e solid_box_ref db the Detailed ANSYS model database produced by ANSYS for the reduced mass data option using master nodes defined at all nodes of the Coarse ANSYS model or SSI model via Guyan reduction e lumped_mass dat and master mass dat The lumped mass data file and the reduced master node mass data file respectively that are produced by ANSYS as explained later in this section e disp _apdl_list txt acc_lump_apdl_list txt and acc_master_apdl_list txt mix_lump_apdl_list txt mix_master_apdl_list txt disp4soil_loads_list cmd The input files that define the APDL output files when user selects to multiple frame files at different time steps in a single analysis run Displacements Option No Nodal Mass Nee
46. decades The COMBIN14 spring element with selected options is equivalent with the ACS SASSI SPRING element type COMBIN14 is convertible with the following limitations KEYOPT 2 or KEYOPT 3 must be defined for the group KEYOPT 2 will take precedence if both KEYOPT 2 and KEYOPT 3 are defined The spring constant must be defined by the by RBLOCK entry KEYOPT 2 options 1 6 are supported and options 1 2 for KEYOPT 3 Copyright 2015 by Ghiocel Predictive Technologies Inc Page 4 of 68 The MASS21 elements are equivalent with nodal masses defined in ACS SASSI Mass data must be defined in the RBLOCK entry The SHELL63 is equivalent to the ACS SASSI SHELL element type The SHELL thickness must be defined by RBLOCK entry The SHELL181 is also convertible for visual simulation only with the limitation that the shell thickness must be defined using section commands The cross section commands are limited to SECTYPE SECBLOCK and SECDATA The SOLID45 is equivalent to the ACS SASSI SOLID element type The SOLID185 is also convertible for visual simulation with the limitation that KEYOPT4 which sets the option for nonuniform materials is not defined or set to 0 The SUBMODELER menu also includes the Export to ANSYS menu option that has an identical functionality with the ANSYS command The active model in the SUBMODELER is exported in the ANSYS Versions 11 12 APDL format when this option is used WARNING The back conversion from ACS SASSI to AN
47. ded l the user wishes to apply only the displacements from the ASC SASSI results to the ANSYS model the Displacements option should be used as shown in Figures 7 and 8 The user should input the following parameters 1 Check the Use Multiple File Lists Inputs if multiple displacement load files will be generated in one run Enter the folder name that contains the ACS SASSI results that was prepared in Stage 1 FASSI Results Enter the HOUSE module input file name which has the hou file extension that was prepared in Stage 1 Solid_box hou Enter the displacement data file for the selected time which was prepared in Phase THD_04 105 00822 or THD_04 105 00844 If Use Multiple File Lists Inputs was checked the file that defines multiple displacement data should be input In our demonstration itis disp_list txt If the user wants to apply rotational displacements as well check the Rotational Disp check box first then input the data file name of rotational displacement in the corresponding edit box If Use Multiple File Lists Inputs was checked the file that defines multiple rotational displacement data should be input in the edit box Enter the folder name that contains the ANSYS model in the Path input box that was prepared in Stage 1 FAANSYS Files Enter the displacement BC APDL command file name in the text box next to APDL file This
48. del These elements will be written overwritten in the destination model lt model gt Number of the destination model lt group gt Group number for element transfer lt estart gt Beginning element in the transfer list lt efini gt End number in the transfer list lt incr gt Element number increment TRANVOL lt model gt Xmin Xmax min Y max Zmin Zmax Transfer all of the elements in a user defined volume into another model specified by destination reference number The volume is cube specified by the minimum and maximum in global coordinates The user can leave any of the boundary arguments blank this will make the code use the default of the model extent for that argument lt model gt Number of the destination model lt Xmin gt Minimum x of the box Copyright 2015 by Ghiocel Predictive Technologies Inc Page 11 of 68 lt Xmax gt Maximum x of the box lt Ymin gt Minimum y of the box lt Ymax gt Maximum y of the box lt Zmin gt Minimum z of the box lt Zmax gt Maximum z of the box CALCMOIl lt normalX gt lt normalY gt lt normalZ gt lt positiveX gt lt positiveY gt lt positiveZ gt lt sysno gt This command calculates the inertia moment of a given cut area for the current active model in a local coordinate system to be defined by the parameters of this command The command is useful for any plane that could be eventually a section cut plane lt normalX gt
49. e default 2 Bonded foundation soil interface using duplicate nodes connected by stiff springs 3 Unbonded foundation soil interface using duplicate nodes connected by soft springs StiffStiff Stiff spring stiffness for Modes 2 and 4 Default 1057 StiffSoft Soft spring stiffness for Modes 3 Default 10 SepLevel Global z coordinate level for the depth where soil separation occurs Mapping This is mapping filename for the duplicate node merging GROUNDELEV lt elev gt This command sets the ground elevation constant for the SSI model This is constant is also set by the HOUSE command lt elev gt The ground elevation for the model GRAVITY lt grav gt This command sets the gravity constant for the model This is constant is also set by the HOUSE command lt grav gt The gravity constant for the model NCOM This command compresses the node list so there are no gaps in the defined node numbering in the current model The command also updates the node element connections in the model to reflect the new node numbering in the model The command will maintain relative order of the nodes in the model GCOM The GCOM command will compress group number so there are no gaps in the group numbering The new group numbering will start a 1 The relative order of the groups will not change and this command does nothing to compress the element numbers in each group use ECOMPR to element numbers inside of groups RMVUNUS
50. e ANSYS ENDRELEASE command creates new nodes and couples these nodes to simulate an end release This cannot be properly represented in ACS SASSI The beam properties must be defined by using the section commands Beams must be defined with the ASEC or RECT type option to be convertible Section Offset must be default or not specified for beams CENT is default for beam and must not be specified for pipes The ANSYS FLUID80 elements are convertible to equivalent solid elements for visual simulations Please note that the FLUID80 element could be used to model fluids contained within pools and vessels having no flow rate Per ANSYS documentation this linearized fluid element is particularly well suited for calculating fluid pressures and fluid structure interaction effects for both static and dynamic applications WARNING The ANSYS FLUID80 elements should be used together with the COMBIN14 spring elements to connect the fluid elements to the structural walls The CP commands should not be used in conjunction with the FLUID80 elements For more application details please see the Problem 48 in the Verification Manual WARNING The ACS SASSI Option AA analysis using the ANSYS FLUID80 elements is based on an approximate linearized approach for the fluid modeling in flexible pools and tanks that is not theoretically exact but is definitely more accurate than the simple mass spring SDOF model approaches which have been used in practice over the last few
51. e using the nodal acceleration data and nodal mass data The user has two options to compute nodal mass data the lumped mass and master node mass The user has the option to generate multiple seismic load files for different selected critical time steps in a single LOADGEN run by checking Use Multiple File Lists Inputs Please note that to use this option the nodal mass data must be generated first using ANSYS as outlined later in this section The ANSYS load generator window for the lumped mass selection is shown in Figures 11 and 12 and for the reduced mass selection in Figures 13 and 14 The user should input all required parameters After clicking the OK button the seismic forces are saved in the APDL input file for example acc load 822 cmd as shown in the bottom input box that is saved in the ANSYS work folder Copyright 2015 by Ghiocel Predictive Technologies Inc Page 40 of 68 Figure 9 Generate Mass Data Using Lumped Mass Option Copyright 2015 by Ghiocel Predictive Technologies Inc Page 41 of 68 ANSYS Static Load Converter Use Multiple File Lists Inputs Fisiveuts SS soidbochou bl BE lt lt F Rotatioal Disp Trans Acceleration Results ff T Rotational Accel Mass Data for Intertial Load Ignore for Displacement Mass Type Lumped Mass Master Node Mass Generate Mass Data Figure 10 Generate Mass Data Using Master Node Mass Option Copyright 2015 by
52. either FI or FV SSI substructuring approaches but for the seismic soil pressure computation using ANSYS only the relative displacements with respect to free field motion computed at the foundation soil interface should be used For this reason the hou file copied in the SASSI Model and Results Input folder FNSSI Results should be modified to include interaction nodes only at the foundation soil interface This can be done by modifying the pre file to define interaction nodes only at the foundation soil interface The modified hou file that is produced by the AFWRITE command is then to be copied in the SSI results folder before the Displacement for Soil Model option is used Copyright 2015 by Ghiocel Predictive Technologies Inc Page 47 of 68 ANSYS Static Load Ce Data to Add From ACS SASSI to the ANSYS model C Displacements Acceleration Displacement and Acceleration C Displacment for Sol Module LT 105 00822 lt lt aca T Rotatioal Disp Trans Acceleration Results acc 04 105 00822 lt lt lt lt T Rotational Accel Figure 15 Displacement and Acceleration Option with Lumped Mass and Single ANSYS Load File Copyright 2015 by Ghiocel Predictive Technologies Inc Page 48 of 68 ANSYS Static Load Ce Data to Add From ACS SASSI to the ANSYS model C Displacements Acceleration Displacement and Acceleration C Displacment for Sod Module Figure 16 Displacement and Acceleration Option wit
53. elected point on the plane lt pointY gt y coordinate of the selected point on the plane lt pointZ gt z coordinate of the selected point on the plane lt normalX gt x component of the normal vector of the selected cut plane in global coordinates lt normalY gt y component of the normal vector of the selected cut plane in global coordinates lt normalZ gt z component of the normal vector of the selected cut plane in global coordinates READSTR lt Filename Dir This command allows the user to read a single stress frame file to compute the section cut forces and moments Once this data is read the section cut command to get the section forces and moments is the CALCPAR command lt Filename gt name of the ess extension stress file to be loaded onto the file including the path lt Dir gt directory where the stress frame file is to be found CalcStessHist lt inpfile gt lt cutnum gt lt pointX gt lt pointY gt lt pointZ gt lt normalX gt lt normalY gt lt normalZ gt lt positiveX gt lt positive Y gt lt positiveZ gt lt sysno gt lt outfile gt Calculates forces and moments of a user defined cross section based on the element stress history frame files the ess extension files This allows the user to batch the section force and Copyright 2015 by Ghiocel Predictive Technologies Inc Page 14 of 68 moment calculation of a section cut for every time step The computed section cut force and
54. ements with end released degrees of freedom in the Coarse ANSYS model the ANSYS model the nodal masses cannot be extracted as these are not compatible with the LUMPM option for modal analysis Refer to section 3 4 3 for an explanation on how to deal with this scenario 3 When select the Master Node Mass option for the Generate Mass Data input using the Detailed ANSYS model the user has to make sure the Detailed ANSYS model has no displacement constraints from the D command in ANSYS on the model The reason same as for above item 2 WARNING It is strongly advised to include all the nodes from the Coarse ANSYS model in the Detailed ANSYS model Since ANSYS will apply the nodal loads to the nodes of the Detailed ANSYS model with the nearest coordinates to the Coarse ANSYS model nodes it is recommended that all the Coarse ANSYS model nodes to be included in the Detailed ANSYS model to ensure that the loads are not applied to incorrect nodes Failure to include coarse model nodes with the same coordinates in the detailed model will require the user to extensively check the detailed model to ensure that the loads from coarse model are applied to the correct locations This checking is a MUST when the detailed model has a different geometry configuration and or different element types than the coarse model This applied load checking is labor intensive and has significant associated risks Also as above mentioned the existence
55. ersions 14 or later are the only versions compatible with Option AA The ANSYS model has to satisfy specific requirements as described below WARNING The ANSYS models to be used for the ACS SASSI Option AA analysis shall not include free nodes that are not connected to any elements If any free nodes exist user shall remove the free nodes and then shall compress the node numbering The ANSYS model shall not include any fixed nodal degrees of freedom with the D command The material damping ratio must to be defined by the BETD parameter The ANSYS model shall include only the following types of elements SOLID element types SOLID45 and SOLID185 SHELL element types SHELL63 and SHELL181 BEAM element types BEAM44 and BEAM188 PIPE element types PIPE288 COMBIN element types COMBIN14 Couple nodes CP command and Constraint equations CE command Multipoint constraint element types MPC184 Rigid Link and or Rigid Beam FLUID element types FLUID80 To use the Option AA capabilities the following steps must be performed prior to the SSI analysis run 1 Generate the ANSYS model mass stiffness and damping matrices using an APDL script that includes the execution of the SSI ANSYS exe program 2 Create the HOUSEFSA module input file hou using SUBMODELER Copyright 2015 by Ghiocel Predictive Technologies Inc Page 62 of 68 Steps 1 and 2 are described in Figure 25 and the text following below APDL t
56. f 68
57. f the selected cut plane in global coordinates lt normalZ gt z component of the normal vector of the selected cut plane in global coordinates CutRmv lt cut num gt lt groupnum gt lt elem 1 gt as lt elem N gt CutRmv lt cut num gt lt groupnum gt RANGE lt estart gt efini incr The two versions of this command are used to remove elements from a section cut data structure The parameters are similar to the CUTADD command lt cutnum gt number of the cur lt groupnum gt number of the group where the elements will be added lt elem 1 gt lt elem N gt element numbers to be added lt estart gt first element to be added lt efini gt last element to be added default is the lt estart gt value lt incr gt increment to the next element default 1 CutCLhR lt firstcut gt lastcut step Clear a cut or list of cuts from memory Once the cut is cleared it no longer exist in memory The user can redefine it by elements to the cut again but attempts to use the cut for submodeling Copyright 2015 by Ghiocel Predictive Technologies Inc Page 13 of 68 purposes will yield errors lt firstcut gt number of the first cut to be deleted lt lastcut gt number of the last cut to be deleted lt step gt step between deleted cuts Cut2Sub lt cutnum gt lt dest gt solid This command make a new model or submodel out of the section cut information defined by the user The active
58. file contains the displacement BC described in APDL commands If Use Multiple File Lists Copyright 2015 by Ghiocel Predictive Technologies Inc Page 34 of 68 Inputs was checked the file disp _apdl_list txt that contains multiple APDL output file names should be input 8 Click the OK button to run the code and generate the displacement BC file in the ANSYS working folder with the file name entered in Step 7 This file can be used for the ANSYS equivalent static stress analysis using the APDL command INPUT Yes Do You want to apply No inertia load e Select Displacements ae Click Generate Mass Data in group box named Mass Data for Inertial Load e Select mass data type and input required parameters e Click button OK to generate APDL command file that will create mass data file and associated files for inertia forces calculation e Run APDL command file in ANSYS after load the corresponding model Mass data associated files will be generated Yes e Select Acceleration Option to generate APDL command file only for inertia forces Do you want to apply inertia load only Option to generate APDL command file for displacements only e Select Displacement and acceleration to generate APDL command file for mixed BC e Run APDL Load File in ANSYS after load ANSYS refined model Figure 6 Basic Flowchart
59. for running the ANSYS load generator Copyright 2015 by Ghiocel Predictive Technologies Inc Page 35 of 68 ANSYS Static Load Converter Data to Add From ACS SASSI to the ANSYS model Displacements Acceleration C Displacement and Acceleration Displacment for Soil Module Use Multiple File Lists Inputs Figure 7 ANSYS Load Generator Displacements Option for Single Load Step File Copyright 2015 by Ghiocel Predictive Technologies Inc Page 36 of 68 ANSYS Static Load Converter Data to Add From ACS SASSI to the ANSYS model Displacements Acceleration C Displacement and Acceleration C Displacment for Soil Module Use Multiple File Lists Inputs SASSI Model and Results Input Path HOUSE Module Input solid_box hou lt lt Displacement Results disp _list txt lt lt ze Rotatioal Disp Trans Acceleration Results mm www lt lt Rotational Accel ANSYS Model and Data Input Mass Data for Intertial Load Ignore for Displacement Mass Type Lumped Mass C Master Node Mass Generate Mass Data For Lumped Mass Lumped Mass Data lt lt For Master Mass Master Node Mass ANSYS Output File ADPL File Figure 8 ANSYS Load Generator Displacements Option with Multiple Load Step Files Generation of Nodal Mass Data for Computing Equivalent Static Seismic Forces for Acceleration and Displacement and Acceleration Options If the user wishes to
60. for the ANSYS detailed stress analysis Before using the LOADGEN module options the user needs to make sure that the appropriate SSI model and result database are used since otherwise the LOADGEN module will not function correctly These must be open in MAIN when LOADGEN is launched The current database path and model name are shown in the bottom right of the MAIN window There are a few things the user needs to pay attention when using LOADGEN 1 Avoid having coincident node locations Avoid having nodes with the same coordinates The load generator uses the nodal coordinates from the SSI model to determine which node in the Detailed ANSYS are loaded Therefore if there are two or more nodes with same coordinates the ANSYS load generator cannot distinguish between these two nodes The coincident nodes will cause the displacements or inertial forces to potentially be applied incorrectly This incorrect load can cause erroneous results in the static analysis When there are coincident nodes in the ANSYS refined model the user should check if the displacement BC s and inertial forces are applied correctly Copyright 2015 by Ghiocel Predictive Technologies Inc Page 26 of 68 2 When the Lumped Mass option is selected for the Generate Mass Data input using the Coarse ANSYS model the user must make sure the Coarse ANSYS model has no displacement constraints from the D command in ANSYS at any node Also if there are beam el
61. h Lumped Mass and Multiple ANSYS Load File Copyright 2015 by Ghiocel Predictive Technologies Inc Page 49 of 68 ANSYS Static Load Ce Data to Add From ACS SASSI to the ANSYS model C Displacements Acceleration Displacement and Acceleration C Displacment for Sod Module a 105 00822 lt lt a T Rotatioal Disp sea Lae ACC 04 105 00822 lt lt lt lt I Rotational Accel Figure 17 Displacement and Acceleration with Master Node Mass and Single ANSYS Load File Copyright 2015 by Ghiocel Predictive Technologies Inc Page 50 of 68 Figure 18 Displacement and Acceleration with Master Node Mass and Multiple ANSYS Load Files Copyright 2015 by Ghiocel Predictive Technologies Inc Page 51 of 68 Use Multiple File Lists Inputs SASSI Model and Results Input solid box hou geg Figure 19 Displacement for Soil Model Option for Single ANSYS Load File Copyright 2015 by Ghiocel Predictive Technologies Inc Page 52 of 68 ANSYS Static Load Converter Data to Add From ACS SASSI to the ANSYS model C Displacements Acceleration C Displacement and Acceleration Displacment for Soil Module Use Multiple File Lists Inputs SASSI Model and Results Input Path HOUSE Module Input solid_box how ge Displacement Results disp_list bet gg Rotatioal Disp Trans Acceleration Results Rotational Accel ANSYS Model and Data Input F ansys_files Mass Data for Intertial Load Igno
62. hiocel Predictive Technologies Inc Table of Contents T INTRODUCTION cerren th ase aa ei sia a ta 2 2 USING THE SUBMODELER MODULE FOR ACS SASSI AND ANSYS FE MODE KING zenou ic chet ei edie cca tense aspen eanadednetGuceen E deat acon 2 2 1 SUBMODELER Converters for ANSYS Models cccccssseeeseeeeeseeeeeseeeesaeees 3 2 2 _SUBMODELER Commands for Checking and Building Complex SSI FEA MOGGI corea nits datee as naar nt aaa ates ation aa tater a aeleseat Soe ener Cea 6 as ACP TOI AOR ANSYS ra eee asec NE 16 Sele Doli MOGSMMGNSSUSS mmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmac 18 3 2 Validation off the Two Step Stress SSI AnalySiS ccccceeeceeeeeeeeeeeeeeeeeaeees 19 3 3 SSI Methodology for Two Step Approach ccccccceccecssseesseeeesseeeesaeeeeseeeeeeas 20 3 3 1 ANSYS Equivalent Static Structural Stress SSI Analyses eseeeeeeeeeee 21 3 3 2 ANSYS Dynamic Structural Stress SSI AnalySe s cccsccceeseeeeeseeeeseees 23 3 3 3 ANSYS Equivalent Static Seismic Soil Pressure SSI Analyses 24 3 4 ACS SASSI ANSYS Interface Description and US sueeeeeeereerreeeeeeeee 25 3 4 1 Requirements and Limitations cccccccsecceeceseeeceeeceeeeneeeseeeseueeneeeseeeeaes 26 3 4 2 ACS SASSI ANSYS Interface DeSCTIPtiONn ccccceccseeeeeeeeeeeeeeeeseeeeseaees 27 3 4 3 ANSYS Seismic Load Generator for Exporting ACS SASSI SSI Responses as Input Boundary Conditi
63. hown in detail in the Demo 6 problem IMPORTANT NOTES Linear Analysis 1 Only the soil model mesh is needed for performing linear soil pressure analysis Once the soil mesh is generated by the SUBMODELER module it can be loaded into ANSYS without the need to include the structural model The Displacements for Soil Module Copyright 2015 by Ghiocel Predictive Technologies Inc Page 57 of 68 option creates a set of Support node relative displacement inputs that can be applied directly to the soil model at foundation soil interface nodes WARNING This option assumes by default the use of FI method with the interaction nodes distributed at the foundation soil interface If FV method is applied or if FI method is used with additional interaction nodes then the hou file has to be modified as described in Section 3 4 3 2 The user should apply appropriate boundary conditions on the soil model boundaries of the soil mesh SUBMODELER automatically fixes all degrees of freedom at the bottom of the soil deposit No boundary conditions are imposed on the lateral surface of the soil model Nonlinear Analysis 3 For this case both the structural and soil models are needed to perform the nonlinear seismic soil pressure analysis These models can easily be merged in ANSYS simply by loading both inp files for structure and soil deposit one after the other The created ANSYS inp files using the ACS SASSI ANSYS interface tools should be lo
64. ightly larger size SSI problems the standard solver becomes numerically inefficient on typical PCs with 16GB RAM since the SSI analysis runtime and the disk storage go up out of hand The ACS SASSI Version 3 0 fast so ver code called Option FS has been extensively verified tested and used for coherent seismic 3D SSI models up to 100 000 nodes including up to 35 000 interaction nodes The fast solver code is much more numerically efficient than the standard solver code The ACS SASSI Version 3 0 fast solver code has two major SSI problem size limitations for current MS Windows PC platforms 1 MS Windows OS limitation The maximum accessed RAM for the SSI problem is limited to 192 GB RAM for Windows 7 and 512 GB RAM for Windows 8 respectively and 2 ACS SASSI limitation The total node number should be less than 100 000 The governing limitation of the SSI problem size is due to the MS Windows OS limitation On MS Windows PCs with 16 GB RAM SSI problems with sizes up to 100 000 nodes including up to 8 000 interaction nodes can be run efficiently with the fast solver using the in core SSI solution algoritm For the SSI problems including larger size models with more than 80 000 nodes and 8 000 25 000 interaction nodes MS Windows PCs with RAM ranging from 32 GB up to 192 GB are recommended For large size SSI problems with more than 20 000 25 000 interaction nodes MS Windows 8 PCs with up to 512 GB RAM are recommended Copyright 2015 by G
65. ile should be input in the APDL File section box This file has similar file format as the input file of multiple displacement data file described in Step 1 The first line is the number of load frame files The subsequent lines are a list of file names that the load data will be saved to This file name should be entered into the APDL File box as shown in Figure 7 Inthe example this file is called disp4soil_apdl_list txt and its content is as follows 2 disp4soil_ 822 cmd disp4soil_844 cmd 4 For generating the seismic loads for the ANSYS model the user is required to select the mass matrix generation option that is either Lumped Mass data option using the Coarse ANSYS model or Master Node Mass data option using the Detailed ANSYS model Theoretically the use of the Detailed ANSYS model reduced mass data for computing the seismic forces provides a more refined numerical solution than using directly the Coarse Copyright 2015 by Ghiocel Predictive Technologies Inc Page 32 of 68 ANSYS model lumped mass data for computing the seismic forces The generation of nodal mass data for computing the seismic forces is described later in this section WARNING The user should make sure the ANSYS model used for generating mass data is able to do modal analysis which implies that there are no released node degrees of freedom using D command in ANSYS model to be used to calculate the structure mass matrix data Stage
66. imitation imposed by ANSYS for the nodal mass calculation This restriction on the node release conditions only affects the mass data generation phase This does not preclude the use of the ANSYS models with released degrees of freedom for performing the equivalent static analysis To generate the mass data based on the ANSYS model with released degrees of freedom the user has to perform some extra steps during the nodal mass generation data phase as outlined below 1 The user needs to make a copy of the ANSYS database db file to use only for the mass generation phase 2 Remove any displacement constraints and any released degrees of freedom from the ANSYS model This will not affect the final results of the equivalent static analysis since this model is only used for the nodal mass data generation 3 Follow the same steps as described on the previous page from Steps 1 through 9 using the ANSYS model with no released degrees of freedom 4 After the nodal mass generation is complete then the unmodified ANSYS model containing released degrees of freedom should be used to perform the equivalent static analysis Copyright 2015 by Ghiocel Predictive Technologies Inc Page 39 of 68 Acceleration Option The Acceleration option is selected by clicking the radio button for Acceleration in the group input box of Data to Add from ACS SASSI to the ANSYS moder This option is used to generate the seismic load input fil
67. ionality implies creating an FE submodel of the surrounding soil deposit in ANSYS Figures 1 and 2 show the new ANSYS FE models created by the ACS SASSI ANSYS interfacing tools that correspond to the two functionalities mentioned above It should be noted that the two step SSI analysis is based ona cascaded analysis assumption in which the SSI responses output from the first step ACS SASSI SSI analysis becomes the input boundary conditions for the second step ANSYS stress analysis In the second step of ANSYS analysis local nonlinear material or geometric aspects can be considered The cascaded assumption implies that there is no feedback effect due to the local structural and foundation nonlinearities on the SSI soil motions at the foundation soil interface This assumption appears to be reasonable for practical applications except for some particular situations when the foundation separation from the surrounding soil is quite large The Option A two distinct functionalities are handled by three separate software modules the Converter module the LOADGEN module and the SUBMODELER module The LOADGEN and SUBMODELER modules are two standalone modules while the Converter module is part of the SUBMODELER module It should be noted that in addition to the Converter included in the SUBMODELER there is another standalone Converter module that is included in the MAIN module menu This older Converter is still available but has fewer capabil
68. is window select the appropriate options for the SSI analysis and any incoherency options that are to be used 14 Check the box next to ANSYS Model Input and select Embedded 15 In the Analysis Option window select the AFWRITE tab Check the box for HOUSE so that the AFWRITE command will generate a new hou input file 16 Assign a model name and full path to the model using the MDL command example mdl ModelName J SSlIproject Model 17 Write the hou input file using the SUBMODELER command AFWRITE The HOUSEFSA input file will be generated in the file name assigned in step 16 with hou as the extension 13 Copy the hou input file to the ACS SASSI working directory that was created in the ANSYS matrix generation tutorial This folder should also include the input files for the SITE POINT and ANALYS modules The user must ensure that to the new hou file produced by AFRWRITE in Step 17 and the new map file produced by MergeSoil in Step 11 as well as the coo and node2eau files generated with ANSYS as described in the previous section are in the ACS SASSI SSI analysis working directory WARNING When the MERGESOIL command is used the 1 model should be the structure model and the 2 model should be the excavation volume It is recommended to compress the node numbering for both ANSYS models if there are skipped nodes so that the node numbering is compact for each model before the two models are merged in SUB
69. ities than the newer Converter included in the SUBMODELER module The key difference is that the MAIN standalone Converter module is limited to the ANSYS Versions 11 and 12 while the SUBMODELER Converter can translate models from the ANSYS Versions 13 and 14 in addition to the ANSYS Versions 11 and 12 Copyright 2015 by Ghiocel Predictive Technologies Inc Page 16 of 68 ANSYS Structural Model Automatically Converted From ACS SASSI Using PREP Module Seismic Loads and Displacements Transfered Using LOADGEN Module st gil ix ae ae F a as as a a s ANSYS Refined Structural Model Be Age ii R rag Using EREFINE command or ascsEs SES EEES MNNG ANSYS GUI rank 1 6 Figure 1 Coarse Model identical to SSI structural model vs Detailed Model user defined AN ANSYS Soil FE Model Is Automatically Generated by SOILMESH Module Embedment mesh is extended User controls extension size and mesh density Can use EREFINE Contact surfaces automatically added by ACS SASSI SOILMESH module Figure 2 Surrounding Soil ANSYS Model Generated by ACS SASSI SUBMODELER Module Copyright 2015 by Ghiocel Predictive Technologies Inc Page 17 of 68 The Converter module translates the ANSYS models saved in the cdb input format into ACS SASSI structural models in the PREP or SUBMODELER pre input format or vice versa translate the ACS SASSI models in the pre format into ANSYS structural models in the APDL input
70. lacement and Acceleration or Acceleration options the user can include local structural nonlinearities in the ANSYS equivalent static analysis The Displacement option applicability is very limited since by using it the user constrains the ANSYS displacement solution to the ACS SASSI displacement solution even in situations when a much more detailed ANSYS model is applied Copyright 2015 by Ghiocel Predictive Technologies Inc Page 28 of 68 ANSYS Static Load Converter Data to Add From ACS SASSI to the ANSYS model Displacements Acceleration Displacement and Acceleration C Displacment for Soil Module Use Multiple File Lists Inputs SASSI Model and Results Input eee HOUSE Module Input e Displacement Results ET E Rotatioal Disp Trans Acceleration Results NN a www a Rotational Accel ANSYS Model and Data Input Path Mass Data for Intertial Load Ignore for Displacement Mass Type fe Lumped Mass s Master Node Mass Generate Mass Data For Lumped Mass Lumped Mass Data ge For Master Mass Master Node Mass _ lt ANSYS Output File ADPL File e Figure 5 ANSYS Static Load Generator Window Launched from ACS SASSI MAIN The Displacement for Soil Mode option is designed to generate the displacement boundary conditions for the ANSYS soil deposit model that is generated by SUBMODELER or SOILMESH in previous revision module and is used to calculate the
71. ld be in the same units as the model either in ft s2 or m s2 e Save the ANSYS model in ACS SASSI format by click the Convert button The command history window shows the converting progress 9 Define the ground elevation using SUBMODELER command GroundElev for example GroundElev 10 would place the ground elevation at z 10 10 Use the SUBMODELER command EtypeGen to define the solid elements in the excavation model as excavated soil elements by typing EtypeGen 2 11 Use the SUBMODELER command MergeSoil merge the structure model number 1 and the excavation model number 2 into a new combined model number 3 a Type actm 3 to switch to the model ID number 3 for the combined model b Use MergeSoil command to combine the structure and excavation models The MergeSoil command also creates a mapping file required by the HOUSEFSA module The mapping file provides the mapping between excavation model nodes and the corresponding combined model nodes Note that this mapping file with extension map should have a standard filename modelname_excv map 12 Generate the interaction nodes using SUBMODELER command IntGen example IntGen 1 generates interaction nodes for the Flexible Volume method Copyright 2015 by Ghiocel Predictive Technologies Inc Page 67 of 68 13 From the menu bar select Options gt Analysis Select the HOUSE tab in the Analysis Options window In th
72. n nodes between the surface and bottom of the foundation The skip argument specifies the number of node layers to be skipped before generating the next layer of interaction nodes For example setting the skip argument to 1 will result in interaction nodes being generated at every other level of nodes in the excavation volume ETYPEGEN type assigns the type of SOLID elements These SOLID elements can be either a part of the structure or a part of the excavation volume based on ETYPE The type is implicitly defined by default ETYPE 0 when an element is added Then during AFWRITE rules are used to determine if implicitly defined elements are structural or excavation hou file However when using WRITE file the implicit ETYPE definition is maintained in the pre file Some INTGEN options require explicitly defined types of elements to work correctly Use ETYPEGEN lt type gt to either explicitly type elements using the AFWRITE rules or changes the type of all the elements in the model Depending on the assigned value the type parameter has the following functionalities Q Changes all implicitly defined element type to explicitly defined element type 1 Sets all elements to structural 2 Sets all elements to soil For checking SSI models FIXEDINT checks SSI model to find if there is any fixed interaction node that is a SSI modeling error No parameter is needed HINGED checks model to find all hinged connections between solid
73. nous mesh model up to ground surface The new excavation model will be stored in the model ID number given by the user The ground surface must be defined properly in the model used in the generation The delta parameter is a factor used to match slight variations in z level used in some models for the same embeddment level Models that don t have uniform z coordinates across the floor should use a delta gt 0 so that the command doesn t generate multiple levels for the small variations of Z lt model gt Model ID number to store the new excavation volume delta allowable distance of z level variation on a single level Default 0 Parameter delta should be entered as a positive floating point number or the default will be used WARNING If there are outcropping beneath ground surface that do not extend to the bottom z level the code will not generate excavation volume for these areas MERGESOIL lt Struct gt lt Soil gt Mode StiffStiff StiffSoft SepLevel Mapping This command is used to merge the structural and the excavation volume models together in a new active SSI FEA model Copyright 2015 by Ghiocel Predictive Technologies Inc Page 7 of 68 lt Struct gt Model Number of the Structure lt Soil gt Model Number of the Excavation volume Mode Merging nodes on the structure excavation interface 0 Unbonded lateral foundation soil interface with side solid 1 Bonded lateral foundation soil interfac
74. o in generate K M C gt 3 m ANSYS out ear aie i gt Step 1 ANSYS is used to build FEA Step 2 SUBMODELER is used to merge the models for Structure and Excavated Structure and Excavated Soil models after Soil and to produce the K M and C converting their ANSYS cdb inputs into new matrices for these models ACS SASSI model formats mm out ovat mis nr a m IL Figure 25 ANSYS Model Information Flow to ACS SASSI To output the ANSYS model matrices the user must run the ANSYS APDL macro called gen_kmc mac This macro as well as the SSI_ANSYS exe program is installed into the ANSYS subfolder in the installation directory This APDL macro contains all the commands needed to generate the model mass stiffness and damping matrices in the binary file format required by HOUSEFSA The SSI_ANSYS exe program is called as part of the APDL macro procedure During the installation the ANSYS_ MACROLIB environmental variable is also set This variable contains the path of the ANSYS subfolder in the installation directory If the SSI model is a surface model then only the ANSYS structure model is needed If the SSI model is an embedded model then both the ANSYS structure and excavated soil models are needed There are a number of preliminary steps that are necessary to output the ANSYS model matrices to be used with the HOUSEFSA module in ACS SASSI If the model is embedded two matrix generation steps will be required
75. ocel Predictive Technologies Inc Page 58 of 68 parameters 3 5 3 Automatic Generation of the Surrounding Soil Deposit SUBMODELER is capable of automatically generating the FEA model of the surrounding soil This surrounding soil model is then used for performing the ANSYS seismic soil pressure analysis either linear or nonlinear In SUBMODELER the user can control the soil model mesh refinement and extension in horizontal and vertical directions independently This action will open the SUBMODELER window as shown in Figure 24 After the soil FEA model grid is generated using SOILMESH command the ANSYS model is exported in the APDL input file format Depending on the selected option this ANSYS soil model can include contact surface elements for performing nonlinear soil pressure analysis to include foundation soil separation effects and foundation sliding if applicable The SUBMODELER module creates the surrounding soil model using SOLID elements as shown in Figure 2 in Section 3 The application of the SUBMODELER module to the ANSYS nonlinear seismic soil pressure analysis is described in detail in the demo problem 6 To create the surrounding soil deposit model the user must first load the ACS SASSI model input file pre file that was used as input for ACS SASSI analysis into the SUBMODELER module Then from the SSI model excavated soil data the SUBMODELER generates the new soil elements using SOILMESH command Finally using the
76. odule is used to generate the APDL load input files for the ANSYS equivalent static analysis or dynamic analysis To demonstrate how the ANSYS load generator is used an illustrative example is considered in the next sections as shown in Figures 6 through 21 All the file paths and names listed below are provided for explanation purposes only Any other paths or file names can be used as long as they follow the guidelines listed in this document The application of the LOADGEN module for ANSYS equivalent static structural stress analysis is shown in detail in the Demo 5 problem which is included on the installation media Stage 1 Input File Preparation Before using the ANSYS seismic load generator the user must prepare the following data files Step 1 Create a folder to save the ACS SASSI model and result files In this first step the user creates a folder to save the necessary SSI analysis result files that will be used for the ANSYS equivalent static analysis This folder called F SSI_Results in this example should contain the following data files 1 ACS SASSI HOUSE input file hou extension for illustration purposes assume that the hou file is named solid_box hou file 2 All necessary relative displacement frame data files from SSI analysis a If an equivalent static analysis in ANSYS is to be performed the relative displacement data files at the selected time steps should be copied to this folder For thi
77. of pairs of duplicate nodes with the same coordinates should be avoided in both models since they can generate the same problem of misplacing the nodal loads in the detailed model 3 4 2 ACS SASSI ANSYS Interface Description The ACS SASSI ANSYS integration modules LOADGEN and SUBMODELER or SOILMESH in previous version are accessible though the ACS SASSI MAIN module After using the SUBMODELER model converter to create a Coarse ANSYS structural model equivalent to the ACS SASSI structural model the user will transfer the seismic loads and displacements from the SSI result database to ANSYS model with the LOADGEN module The ANSYS load generator the LOADGEN module provides four functions to convert the SSI displacements and or accelerations at all or selected critical time steps from the ACS SASSI results into the ANSYS seismic load via APDL format input file as shown in Figure 5 The four options are organized in the first user input data group labeled as Data to Add from ACS SASSI to the ANSYS model 1 Displacements option provides the function to apply displacements only 2 Acceleration option provides the function to apply inertial forces only Copyright 2015 by Ghiocel Predictive Technologies Inc Page 27 of 68 3 Displacement and Acceleration option provides the function to apply both displacement boundary conditions and seismic forces from nodal accelerations which here will be referred to as a mi
78. oint constraint element types MPC184 Rigid Link and or Rigid Beam and x FLUID element types FLUID80 For ANSYS models with elements that are compatible with ACS SASSI such as BEAM4 BEAM44 SOLID45 SHELL63 COMBIN14 and MASS21 the SUBMODELER Converter has the same limitations as the MAIN Converter with the exception that it can handle inputs from the ANSYS Versions 13 14 models and therefore it is not limited to ANSYS Versions 11 12 as the MAIN Converter is The SUBMODELER Converter limitations are described below Copyright 2015 by Ghiocel Predictive Technologies Inc Page 3 of 68 The Material Data must be defined using the MPDATA command unless otherwise specified Any other way of defining this data is not recognized by the Converter The BEAM4 BEAM44 elements are convertible with some limitations These beams must be defined with the K node definition These beams must have properties defined by the RBLOCK and the RBLOCK entry for the property must have 6 8 10 12 or 19 24 fields for this element to be converted properly The end releases are defined by KEYOPT 6 and 7 The cross section commands are limited to SECTYPE SECBLOCK and SECDATA The BEAM188 and PIPE288 elements are convertible with the following limitations Pipes are converted to equivalent beams only for visual simulation These elements must be defined with a K node definition WARNING End releases for these elements cannot be defined for these beams becaus
79. ons to ANSYS Model LOADGEN Module 30 3 5 ANSYS Equivalent Static Analysis for Foundation Soil Pressures 57 Gas Sa FH Sa AT AV SIS SUC mmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmkymrHHmHHHiHHm rr 57 35 22 Nonlinear Analysis bml mmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmi 57 3 5 3 Automatic Generation of the Surrounding Soil Deposit eeeeeeeeeeeeersee 59 4 OPTION AA OR ADVANCED ANSY S 0 cccecccceecceceeeceeeeeeeseeseeseeeeesaeeeesaeeeesaaes 61 4 1 ANSYS APDL Procedure to Generate Structural Matrices seeeeeeeeeeeeeeee 62 4 2 Using SUBMODELER to Generate the HOUSEFSA Input File 0 0 64 Aie SUMACESo NIOGEIS xj cscs ere os eo eeergescnscgasatnaniea a atenceeng teeeseeeaes 65 A 2 2 EMbECddEd SSI MOCEIS mmmmmmmmmmmmmmmmmmmmmmmrmrmmmrmrmrmrmm mmmmmmmmkcyiirmr 66 4 3 Running the HOUSEFSA Module ncs 68 Copyright 2015 by Ghiocel Predictive Technologies Inc Page 1 of 68 1 INTRODUCTION The ACS SASSI ANSYS interfacing capability provides an advanced two step SSI approach that is capable of including more refined FEA structural models local nonlinear material and or nonlinear geometric aspects within the structure or at foundation interface with the soil There are two ACS SASSI ANSYS interfacing options i Option A or ANSYS and ii Option AA or Advanced ANSYS Three demo problems Demo 5 6 and 7 are provided to help users understand how to
80. or Eguivalent Static Structural Analysis Computing a Element Stress Seismic Soil tk Pressures Time SSI Solution Time Frames As Equivalent Static Loading at Critical Time Steps EQS Forces Linear amp Nonlinear EQS Relative Displacements Linear Welded Figure 4 Seismic Soil Pressure Equivalent Static SSI Analysis Nonlinear Linear Analysis Using Seismic Loads left and Linear Analysis Using Support Displacements right 3 4 ACS SASSI ANSYS Interface Description and Use The ACS SASSI ANSYS interface capability provides an efficient tool to perform the second analysis step using a Detailed ANSYS model The ACS SASSI ANSYS interface tool LOADGEN module automatically generates the SSI boundary condition input files for the Detailed ANSYS model The SSI boundary condition inputs consist of the nodal seismic forces within the structure and or nodal relative displacements at the foundation interface with surrounding soil The required SSI boundary conditions are automatically transferred to ANSYS in an APDL format input file This APDL file contains nodal forces and or relative displacements for ANSYS equivalent static analyses and nodal displacements and acceleration field data for ANSYS dynamic analyses The Copyright 2015 by Ghiocel Predictive Technologies Inc Page 25 of 68 type of SSI boundary condition input is selected by the user from the A
81. ositiveX gt x component of the local system orientation for X axis direction in global coordinates lt positive Y gt y component of the local system orientation for X axis direction in global coordinates lt positiveZ gt z component of the local system orientation for X axis direction in global coordinates lt sysno gt the local system number where the local system will be stored CutVol lt cutnum gt Xmin Xmax min Y max Zmin Zmax This command adds new elements to the section cut data defined by the user with the lt cutnum gt argument by using volume selection The selected volume is defined by the other arguments in the command The user can leave and or all of the volume boundaries empty By default any boundary argument left empty will be replaced by the appropriate minimum or maximum for the active model lt cutnum gt Number of the destination cut lt Xmin gt Minimum x of the box lt Xmax gt Maximum x of the box lt Ymin gt Minimum y of the box Copyright 2015 by Ghiocel Predictive Technologies Inc Page 12 of 68 lt Ymax gt Maximum y of the box lt Zmin gt Minimum z of the box lt Zmax gt Maximum z of the box CutAdd lt cut num gt lt groupnum gt lt elem 1 gt ar lt elem N gt CutAdd lt cut num gt lt groupnum gt RANGE lt estart gt efini incr Both above versions of this command allow the user to add new elements to a section cut data defined by the user with
82. ps These critical time steps are usually those that produce the largest base shear sliding forces and overturning moments WARNING It should be understood that the soil pressure calculation is an approximate approach that is not theoretically exact for nonlinear analyses The first action taken by the user before performing the seismic soil pressure analysis is to generate the ANSYS submodel for the surrounding soil deposit This soil model is then used for the soil pressure analysis Using the SUBMODELER module the user can automatically generate a surrounding soil deposit model full control over the mesh refinement and extension In general for an equivalent static stress analysis the soil deposit should extend about twice the size of the foundation to eliminate any effect the soil deposit boundaries away from the foundation area may have on the soil pressure results The user could perform some sensitivity studies on the soil mesh sizes and its extension in lateral and vertical directions to ensure that both are correctly sized for the problem NOTE The user could use limited extension surrounding soil model with displacement boundary conditions input from SSI analysis Two ACS SASSI ANSYS equivalent static approaches are implemented as shown in Figure 4 i Linear Analysis foundation is bonded with the elastic soil uses as the SSI boundary condition inputs the SSI foundation soil interface node relative displacements with respect to the
83. ps can be selected by the user using the ACS SASSI PREP time history visualization tools or more efficiently by using the automatic stress peak selection option in the ACS SASSI PREP Batch menu Using LOADGEN the seismic load and foundation displacements at all or selected critical time steps will be transferred automatically to ANSYS model in the APDL format in separate load steps The final stress results should be obtained by the user by enveloping the absolute value results from different load steps WARNING No output requests are included in the load step files The output request is entirely at the ANSYS user discretion and responsibility It should be noted that user is also able to select only a portion of the structure as a submodel for further perform the detailed stress analysis The Displacements and Acceleration options could be combined so that SSI relative displacements are transferred at the boundary nodes of the submodel and the seismic forces are applied at the submodel interior nodes In this case the user has to select all the structural nodes around the selected portion of the structure as interaction nodes so that LOADGEN will transfer the node relative displacements of these nodes as SSI boundary conditions into the ANSYS APDL file lt should be noted that the traditional ZPA based approach that uses the SSI maximum nodal acceleration response values to compute equivalent static seismic forces could be applied in
84. ption The user can also select to generate multiple ANSYS load files by checking Use Multiple File Lists Inputs Figures 15 and 16 show the inputs using the Lumped Mass data option Figures 17 and 18 show the inputs using the Master Node Mass data option Once the seismic load file is generated it can be applied to the Detailed ANSYS model as described for the other two loading options Displacements for Soil Model Option This option is used to convert the ACS SASSI displacement results at the interaction nodes into the displacement BCs for the ANSYS soil model used to compute the seismic soil pressures on foundation walls The input is the same as for the Displacement option described in earlier in this section Figures 19 and 20 show the user s inputs for this option WARNING ONLY the SSI interaction nodes at the foundation soil interface may be included in the model used by the SUBMODELER module By default the SUBMODELER module assumes that the ACS SASSI SSI model uses the Flexible Interface FI method with SSI interaction nodes defined only at the foundation soil interface If the seismic SSI analysis was performed using the Flexible Volume FV method or Flexible Interface with additional nodes on the excavation volume surface then the HOUSE input file must be modified to include only the SSI interaction nodes that are at the foundation soil interface It should be noted that the SSI analysis can be done with
85. re and excavation models are merged in SUBMODELER the user can use the AFWRITE command for the HOUSE module to generate the hou input file required by the HOUSEFSA module The procedure of generating the hou input file for the HOUSEFSA run is described in detail in the following sections 4 2 1 Surface SSI Models For surface SSI models only the ANSYS structure model cdb file is needed There are 12 steps to create the HOUSEFSA module input file hou 1 Create a working directory in which the HOUSE input file hou of the HOUSEFSA will be created using SUBMODELER 2 Copy the ANSYS cdb file of the structure model into the new created SUBMODELER working directory 3 Start the SUBMODELER module 4 Convert the ANSYS structure model into the ACS SASSI format using SUBMODELER by selecting Model gt Converters gt ANSYS cdb from the menu bar A dialog box will open In the dialog box input the following data a Inthe Input File Name box input the ANSYS cdb file name including path by typing or browsing b In the Output pre File Name box input the corresponding pre file name including path Optional step c In the Save Converted Data to Model Number box enter the model ID number for the structure model By default this will save the converted model to model 0 The model ID number entered here should be an unused ID number in the current session For this example use 1 for the model ID d In the Enter Value for Gra
86. re for Displacement Mass Type Lumped Mass s Master Node Mass Generate Mass Data For Lumped Mass Lumped Mass Data ae For Master Mass Master Node Mass D ANSYS Output File i ADPL File disp4soil loads list cmd Figure 20 Displacement for Soil Model Option with Multiple ANSYS Load Files Stage 2 Using LOADGEN for ANSYS Dynamic Analysis To run this option select RUN gt ANSYS Dynamic Load from the ACS SASSI MAIN menu This will open the ANSYS Dynamic Load Converter window for generating the seismic loading and support boundary conditions for the ANSYS dynamic analysis load as shown in Figure 21 Since the user has prepared all the necessary data in stage 1 the user just needs to fill the input boxes in ANSYS Dynamic Load Converter window with relevant items Copyright 2015 by Ghiocel Predictive Technologies Inc Page 53 of 68 1 Inthe Path box in the SASSI Model and Results Input section enter the path of the folder that contains the displacement frames F ssi_results 2 Inthe HOUSE Module Input box enter the file name of the hou file or browse to it by clicking on the arrow next to the box solid_box hou 3 Inthe Ground Acceleration File box input the name of the acceleration file ground_acce ixt This file will be prepared by the user for the ANSYS dynamic analysis The file format of the ground_acce txt file is described in the next section
87. rrespondence between the original and the new beam groups SOILMESH lt Model gt lt Scale X gt lt Scale Y gt lt Hori gt lt Vert gt lt mX gt lt mY gt lt Thick gt lt Contact gt lt RC num The SOILMESH command creates a soil FE mesh for the active model and stores the model data in the user specified Model lt Model gt User specified integer model number lt Scale X gt Percentage of growth in the X direction of each level i e 0 07 lt Scale Y gt Percentage of growth in the Y direction of each level i e 0 07 lt Hori gt Number of horizontal levels to build away from the embedment lt Vert gt Number of vertical levels to build away from the embedment lt mX gt Centroid correction in the X direction lt mY gt Centroid correction in the Y direction lt Thick gt Thickness of each new level lt Contact gt If equal 0 do not use contact surfaces else include contact surfaces in the model lt RC num gt Defines the constant set number to be used in ANSYS for the contact surface Real Constants WARNING If the excavation volume has lateral walls that are not vertical or if the node layers are different at different excavation levels then SOILMESH will not work correctly EXCAV lt model gt delta This command creates an excavation volume model for a SSI model that doesn t have an excavation volume The command will use the lowest vertical z level grid as a template to create a homoge
88. s and shell and beams and beams and shells These hinged connections could indicate potentially incorrect FE modeling since the node rotations from beams and shells are not transmitted to solids at the common nodes and the node rotations from beams are not transmitted the in plane shell rotations at the common nodes the drilling dof equations have no stiffness terms by default KINT The command will check the K nodes of all Beams to see if they are also defined as interaction nodes K nodes that are interaction nodes may cause incorrect simulation results This command will report the nodes that have this issue to the user and remove the node from interaction node list Copyright 2015 by Ghiocel Predictive Technologies Inc Page 9 of 68 FREESPRING This command will find all unconstrained node dofs that are only connected to a spring and warn the user about this condition at the nodes where it occurs For improving SSI models FIXROT lt Stiff gt This command automatically fixes the unnecessary rotational degrees of freedom and adds soft rotational springs to improve numerical conditioning for shell models for the Kirckhoff plate element the drilling degree of freedom has no stiffness associated with it and therefore could produce poorly conditioned or unstable numerical models Using FIXROT lt Stiff gt will fix all rotational dofs for nodes that belong only to solid elements or shell elements that are parallel to global system
89. s are used in the ANSYS model they will be automatically transformed into dummy BEAM elements by the SUBMODELER converter Any hou input file generated from the AFWARITE command that contains these dummy elements will also contain a flag to indicate that the input file should not be used directly in any SSI analysis as it ONLY contains information on the model geometry This will have no impact on the SSI analysis using Option AA since the HOUSE model will use the ANSYS matrices directly without reading any element material or section information from the hou file While none of the matrices Copyright 2015 by Ghiocel Predictive Technologies Inc Page 61 of 68 are formed from the hou file that contains the dummy elements this hou file is still needed for the FE model configuration information including node coordinates element groups element connections which are needed for the ACS SASSI post processing of the SSI results including Structural animations 4 1 ANSYS APDL Procedure to Generate Structural Matrices Before the modified HOUSE fast solver module for Option AA can be used the ANSYS model matrices need to be extracted The modified HOUSE module can then be used to read these matrices and convert them in the appropriate format for the ACS SASSI SSI analysis lt should be noted that in Option AA ANSYS models can include more sophisticated element types than the basic element types included in ACS SASSI ANSYS V
90. s example assume that the names of these data files are THD_04 215 00844 and THD_04 105 00822 Copyright 2015 by Ghiocel Predictive Technologies Inc Page 30 of 68 b If a dynamic analysis in ANSYS is to be performed then all the displacement data files at all time steps should be copied to this folder For this example assume that the file names are THD 00 000 00001 THD_00 005 00002 THD_ 14 995 03000 3 All necessary acceleration frame data files from SSI analysis a If an equivalent static analysis in ANSYS is to be performed the acceleration data files at selected times should be put in this folder such as ACC_04 215 00844 and ACC 04 105 00822 in the example b If adynamic analysis in ANSYS is to be performed the input ground acceleration history data file including the six degrees of freedom components in space should be copied to this folder In this example we assume that this file is named NEWMHX ACC 4 If multiple critical time steps for defining the seismic loads for ANSYS analysis are to be used then an input file with the list of the frame data files must be created The first line of this file contains the number of frame files that the user will use to generate seismic load files for ANSYS analysis The subsequent lines are the list of the file names containing the SSI response frames To use the multiple file input option the user should select this option
91. seismic soil pressures on foundation walls and mats WARNING Currently only the Flexible Interface method with interaction nodes at the foundation soil interface Subtraction is supported by default for the Displacement for Soil Model option The application of the Flexible Interface method with additional SSI interaction nodes Modified Subtraction or the application of the Flexible Volume method is possible only if the user creates a new SSI model that has the SSI interaction nodes defined only at the foundation soil interface Using the AFWRITE command for HOUSE the user will create a new hou file that is then copied Copyright 2015 by Ghiocel Predictive Technologies Inc Page 29 of 68 in the ACS SASSI result folder This hou file will be identical to the hou file used for the SSI analysis with the exception of the interaction nodes Seismic load files can be defined either at a single time step or at multiple time steps In the latter case the user will need to create a file with the list of the SSI response frame file names rather than use a single file name as input The format for this file is detailed in the next section 3 4 3 ANSYS Seismic Load Generator for Exporting ACS SASSI SSI Responses as Input Boundary Conditions to ANSYS Model LOADGEN Module The use of the ANSYS seismic load generator consists of two stages 1 Stage 1 is the input file preparation stage and 2 Stage 2 is the running stage when the LOADGEN m
92. te displacements An alternate for the boundary condition inputs is to load the ANSYS model with the rigid body kinematic SSI accelerations and relative displacements at the support nodes This alternate approach works well for the surface foundations under vertically propagating waves for which there is no kinematic SSI effects so that the kinematic SSI accelerations are identical with the free field accelerations The LOADGEN module functionality support both alternate approaches lt should be noted that ANSYS direct integration approach is limited in practice to the Rayleigh damping matrix option that assumes that structural damping is frequency dependent This is a significant modeling limitation since for the structural and soil hysteretic materials the damping is independent of frequency so that the Rayleigh damping can be too crude The use of the frequency dependent Rayleigh damping could significantly overdamp the low and the high frequency structural responses Also ACS SASSI uses a structural mass matrix that is a mixed lumped and consistent mass matrix while ANSYS uses either a lumped mass matrix or a consistent matrix for the direct time domain integration approach Thus some visible differences between the ACS SASSI dynamic response and the ANSYS dynamic response are expected 3 2 Validation of the Two Step Stress SSI Analysis The high computational accuracy of the implemented ACS SASSI ANSYS dynamic and equivalent static SSI stress
93. ted that the use of the FIXROT FIXSHLROT commands is highly beneficial for improving the numerical condition of the FEA shell models The use of FIXROT FIXSHLROT makes the two FEA codes provide same results for the identical configuration shell models using SHELL63 in ANSYS to be consistent with the ACS SASSI Kirckhoff thin plate element formulation The use of FIXROT FIXSHLROT has no improving effects when the ANSYS FE shell models are used directly via the Option AA capability For the Section Cut option SECDATAOPT lt flag gt This command sets the ess extension files output request in the STRESS input file When the flag is set to 1 then the element center stress time history files the ess files will be saved Their names will be the same names like the nodal stress ths files except that the extension is ess instead of ths flag User output request for saving the element center stress files with the ess extension 0 no ess files will be saved 1 the ess files will be saved for the entire time history duration CALCM This command calculates the total mass of the elements in the active model based on material density and the element volumes and the total lumped mass based on the nodal masses CALCCOG This command calculates the center of mass for the active model TRANELEM lt model gt lt group gt lt estart gt lt efini gt lt incr gt Transfers a list of elements from the active model to another new mo
94. the lt cutnum gt argument The first version of this command is intended for the user to enter a disjointed list of elements from one group while the second command is intended for use with a continuous list of elements or a list with regular gaps between desired elements This command will create the section cut in memory if no cut has been defined lt cutnum gt number of the cur lt groupnum gt number of the group where the elements will be added lt elem 1 gt lt elem N gt element numbers to be added lt estart gt first element to be added lt efini gt last element to be added default is the lt estart gt value lt incr gt increment to the next element default 1 SLICE lt cutnum gt lt pointX gt lt pointY gt lt pointZ gt lt normalX gt lt normalY gt lt normalZ gt This command will generate in memory user defined section cut plane lt cutnum gt with all of the elements that cross the infinite plane The cut plane is defined by a point in space and its orientation with respect to the global coordinate planes lt cutnum gt section cut number lt pointX gt x coordinate of the selected point on the plane lt pointY gt y coordinate of the selected point on the plane lt pointZ gt z coordinate of the selected point on the plane lt normalX gt x component of the normal vector of the selected cut plane in global coordinates lt normalY gt y component of the normal vector o
95. the reduced mass matrix option ii is used then the Detailed ANSYS Copyright 2015 by Ghiocel Predictive Technologies Inc Page 20 of 68 model will be used directly for computing the reduced mass matrix data or the master mass that corresponds to the node dofs of the Coarse ANSYS model The user must make sure the Detailed ANSYS model includes no D node dof constrains 3 3 1 ANSYS Equivalent Static Structural Stress SSI Analyses Three options for the ANSYS quasi static or equivalent static SSI are implemented These three options depend on the type of the seismic SSI responses used for the second step analysis 1 Accelerations for all structural dofs This still needs calibrated soil springs at the foundation support nodes i Accelerations for all structural dofs and Displacements for the foundation soil interface nodes and iii Displacements for all structural dofs The last two of the above equivalent static approaches are theoretically exact for identical structural FE models in ACS SASSI and ANSYS Figure 3 reviews the capabilities of the three equivalent static analysis approaches These equivalent static approaches can use SSI seismic loads and or displacements that are transferred at each time step or at selected critical time steps These critical time steps tk are those for which maximum structural stresses forces are reached in different parts of the structure at different time steps These critical time ste
96. tion Soil Pressures This section describes the procedure used to perform an ANSYS equivalent static seismic soil pressure analysis 3 5 1 Linear Analysis Steps e Perform SSI analysis using ACS SASSI e Create ANSYS model input file using ANSYS model converter and load it in ANSYS e Using ANSYS Load Generator LOADGEN create ANSYS load input files in APDL format e Using ANSYS Soil Mesh Generator SOILMESH create soil model e Convert soil model to ANSYS using SOILMESH ANSYS command and load the APDL soil model in ANSYS e Load the APDL input with generated node displacements in ANSYS e Solve using ANSYS 3 5 2 Nonlinear Analysis Steps e Perform SSI analysis using ACS SASSI e Create ANSYS structural model input file using the ANSYS model converter e Load the ANSYS structure model e Using ANSYS Load Generator LOADGEN create ANSYS load input files in APDL format e Using ANSYS Soil Mesh Generator SUBMODELER create soil model grid eventually including contact surfaces e Create the ANSYS soil model using SUBMODELER ANSYS command e Load the APDL soil model in ANSYS e Load the APDL input file for seismic loads on structure in ANSYS e Load the APDL soil model e Run ANSYS for the integrated structure surrounding soil model with or without contact surfaces at foundation soil interface A complete example for using Option A for computing seismic soil pressures on an embedded foundation including soil separation effects is s
97. vity box input the gravity acceleration the gravity acceleration should be in the same units as the model either in ft s2 or m s2 e Save the ANSYS model in ACS SASSI format by click the Convert button The command history window shows the converting progress f Type actm 7 to make the converted model the active model in SUBMODELER 5 Define the ground elevation using SUBMODELER command GroundElev for example GroundElev 10 would place the ground elevation at z 10 Copyright 2015 by Ghiocel Predictive Technologies Inc Page 65 of 68 6 Generate the interaction nodes using SUBMODELER command IntGen example IntGen 4 generates interaction nodes for surface models 7 From the menu bar select Options gt Analysis Select the HOUSE tab in the Analysis Options window In this window select the appropriate options for the SSI analysis and any incoherency options that are to be used 8 Check the box next to ANSYS Model Input and select Surface 9 Inthe Analysis Option window select the AFWRITE tab Check the box for HOUSE so that the AFWRITE command will generate a new hou input file 10 Assign a model name and full path to the model using the MDL command example mdl ModelName J SSlIproject Model 11 Write the hou input file using the SUBMODELER command AFWRITE The HOUSEFSA input file will be generated in the file name assigned in step 10 with hou as the extension
98. x component of the normal vector of the selected cut plane in global coordinates lt normalY gt y component of the normal vector of the selected cut plane in global coordinates lt normalZ gt z component of the normal vector of the selected cut plane in global coordinates lt positiveX gt x component of the local system orientation for X axis direction in global coordinates positive Y gt y component of the local system orientation for X axis direction in global coordinates lt positiveZ gt z component of the local system orientation for X axis direction in global coordinates lt sysno gt the local system number where the local system will be stored For a horizontal plane in which a local system in the plane with local X in the direction of global X the input parameters should be 0 0 1 1 0 0 with the default 1 for the system number CalcPar lt normalX gt lt normalY gt lt normalZ gt lt positiveX gt lt positiveY gt lt positiveZ gt lt sysno gt This command same parameters as CALCMOI It computes for a given cut area centroid the moment of inertia and current stress calculation for the active model lt normalX gt x component of the normal vector of the selected cut plane in global coordinates lt normalY gt y component of the normal vector of the selected cut plane in global coordinates lt normalZ gt z component of the normal vector of the selected cut plane in global coordinates lt p
99. xample use 1 for the model ID Copyright 2015 by Ghiocel Predictive Technologies Inc Page 66 of 68 d In the Enter Value for Gravity box input the gravity acceleration the gravity acceleration should be in the same units as the model either in ft s2 or m s2 e Save the ANSYS model in ACS SASSI format by click the Convert button The command history window shows the converting progress 6 Define the ground elevation using SUBMODELER command GroundElev for example GroundElev 10 would place the ground elevation at z 10 7 Type actm 2 to switch to model ID number 2 which will be used for the excavation model 8 Convert the ANSYS excavation model into the ACS SASSI format using SUBMODELER by selecting Model gt Converters gt ANSYS cdb from the menu bar A dialog box will open In the dialog box input the following data a Inthe Input File Name box input the ANSYS cdb file name including path by typing or browsing b In the Output pre File Name box input the corresponding pre file name including path c In the Save Converted Data to Model Number box enter the model ID number for the structure model By default this will save the converted model to model 0 The model ID number entered here should be an unused ID number in the current session For this example use 1 for the model ID d In the Enter Value for Gravity box input the gravity acceleration the gravity acceleration shou
100. xed boundary condition 4 Displacement for Soil model option provides the function to generate the displacement boundary conditions for soil FE model that is used to compute the seismic soil pressures on embedded foundation walls and base slab The Displacement option is the simplest to use and requires the least amount of input data The Acceleration option requires the user to prepare the nodal mass data first If the Acceleration option is selected then user will need to define soil springs at the foundation support nodes in order to simulate the soil deposit stiffness The structural seismic forces are automatically calculated using either the Lumped Mass matrix option for the Coarse ANSYS model or the Reduced Mass matrix option for the Detailed ANSYS model The Reduced Mass matrix corresponds to a reduced model produced by the master nodes selected at the locations of all the nodes contained in the Coarse ANSYS model The computation of the soil springs at support nodes will likely not be a trivial calculation for the user especially for embedded foundations Alternately the Displacement and Acceleration option or Mixed option can be used This option provides theoretically exact boundary conditions BCs for the ANSYS equivalent static analysis We strongly recommend the use of the Displacement and Acceleration option for application to all SSI problems It should be noted that using the Disp

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