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LARSA 4D Introductory Training Manual for Bridge

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1. We will create a new construction step at the end of our construction sequence for stressing the tendon e Open the Construction Stages Explorer ex Click on Stage 1 to activate it and then click on Add Step to add a new step to the end of the stage Right click the new step and choose Tendon Activities In the activity spreadsheet add a new row Change the Tendon to Tendon 1 WF Tendon Activity fs fon Ex Sunnott amp Hnist Activity Slave Master Activity Tendon Activity Displacement Initializations Tendon Activity Stressed W 1 2 show Only Selected Objects Tendon Stressing Activity Close the activity spreadsheet Be sure the activity appears correctly at the end of the Construction Stages Explorer LT Remove Temporary Loads 2 Temporary Loads 3 f 1 00 4 Temporary Loads 4 f 1 00 EH step Tendon 1 Stressed mH Tendon Stressing Activity Tendon Results Re run the Staged Construction Analysis Close the analysis window after it completes successfully Use deformed model graphical results and step through the contruction stages again Verify that the last step for stressing the tendon exists and that the structure has the expected response The incremental option in the Graphical Results Options floating window is useful in this case When this option is on the results show the changes from the previous step rather than the
2. Ee Ee s 3 3g In the Load Cases Explorer add a new load case named Influence Line Right Open the spreadsheets for the load case by double clicking the load case Then go to the Moving Loads tab and then choose Influence Loads beneath the tabs Add a new row to the spreadsheet Change the lane column to Right Lane Set the Forward Increment to 2 feet Repeat the process to create a Influence Line Left load case Then close the loads spreadsheet Run a Moving Load Analysis from the Analysis menu There are no options for this analys Just click Analyze and confirm to save the project Close the analysis window when it completes successfully 25 LARSA 4D Introductory Training Manual for Bridge Projects Vehicle and UDL Setup The influence analysis in LARSA 4D was developed with AASHTO LRFD and AASHTO LFD in mind although the influence solver can be used for many design specifications We will use AASHTO LRFD in this example In the AASHTO LRFD code a lane is loaded with combinations of a Design Tandem Design Truck and a Design Lane Load LARSA 4D s standard load pattern database consists of the following two load patterns suitable for this code HL 93 Design Truck in conformance with AASHTO LRFD 3 6 1 2 2 This truck has three axles of 8 32 and 32 kips spaced a minimum of 14 ft apart The spacing between the two 32 kip axles may vary between 14 ft and 30 ft to produce extreme force effects Loads ar
3. Geometry The Joints spreadsheet is the first spreadsheet that opens in the Geometry group In the blank row enter the coordinates 0 0 0 After the first value is entered the row becomes initialized as a joint Spreadsheets always have a final blank row which is used to enter more data Repeat this to enter joints at 100 0 0 and 200 0 0 The structure will be supported by bearings which will be modeled as a grounded spring elements later on As a result we do not need to set any translation or rotation restraints here r Fi Joints Joints Members Plates Springs Mass Elements A Isolators Bearings Tendons Le Joints Slave Masters Rigid Links Rigid Diaphragms x Y zZ Translation Displacemen t ID ft ft ft DOF Rotation DOF UCS 1 0 0000 0 0000 0 0000 all free all free Global 2 100 0000 0 0000 0 0000 all free all free Global z 200 0000 0 0000 0 0000 all free all free Global Joints Spreadsheet Members To create the girder it is also possible to use a spreadsheet We will instead use the drawing tool to show more of the capabilities of LARSA 4D Change to the Graphics View window by clicking the window button at the bottom of the screen Then click the toolbar button for Zoom Extents The drawing command allows us to click the joints where members should go 11 LARSA 4D Introductory Training Manual for Bridge Projects Inthe Draw menu activate Geometry M
4. Cases Time History Cases Pushover Cases Combo with Moving Load Cases Stage Analysis Scenario s Staged Construction Results s Turn on graphical deformation diagrams and set the scale factor to 128 Then step through the construction steps by clicking on them to observe the analysis sequence Staged Construction Results Third Segment Step e Turn off deformed model when you are done You can of course check the results numerically as well Using complete rendering the construction sequence can be visualized by stepping through the analysis results Deformation Results Getting Out of Staged Results As you step through the construction stage input or through staged construction results you may find that the model starts to become grey or disappear Elements that have not yet been constructed in the selected construction step or result case are shown greyed or in some results and when complete rendering is turned on hidden entirely This may become inconvenient as you move between results and revising model input Or the graphics may become out of sync with the result case you are viewing 39 LARSA 4D Introductory Training Manual for Bridge Projects When elements are greyed or hidden a button appears in the Construction Stages Explorer called View Full Model Click this button to reset the graphical view to show all elements regardless of whether they have been constructed or not If any stage or step is selected
5. Complete Rendering You may want to use the graphics rotation tools to get a better view Complete rendering of the model so far s Turn off complete rendering using Graphics Simple Rendering and if necessary return the graphics view to a side view Pier Bearing The pier will be modeled as a bearing a grounded spring acting in the z elevation direction only 12 LARSA 4D Introductory Training Manual for Bridge Projects Although the pier joint is located at the girder centroid and the bearing only connects at the bottom of the T shape because the bearing acts in the z direction only its vertical position is not relevant We will pay closer attention to the bearings at the abutments Return to the geometry spreadsheets and change to the Springs tab ee Add a new row to the spreadsheet using the Add Row tool in the toolbar or in the Edit menu Or just start typing into the blank row In the I Joint cell enter joint number 2 Leave the J Joint cell empty signifying that this is a one node i e grounded spring Change the spring direction to Trans Z and set its K Tension value to 1e8 The K Compression cell updates to have the same value since a linear spring must have equal stiffness in both tension and compression Spring directions are in joint displacement coordinate system directions All of our joints in this tutorial use the Global Coordinate System as their displacement coordinate system and so we
6. Joint Displacements Translation Z in Joint 10 Displacement Graph Close the graph window Change to moment diagrams and turn on the incremental option to see the effects of time at each stage Then turn off the incremental option We can also display the total effects of static loads post tensioning and each time dependent effect separately That is the cumulative effects of the different types of loading on the structure LARSA 4D calls this extraction of partial effects by load class Select the last result case Five Years Other PT Losses In the floating Graphical Results Options floating window change View Full Cumulative Results to Extract Prestress Loss Relaxation This load class is used for long term post tension relaxation effects Graphical Results Options T A b Moment Mz Extract Prestress Loss Relaxation 1104 71 371 41 Partial Cumulative Effect for Relaxation s Turn off graphical results Finally we can go back to the tendon results to see the changes in the forces within the tendon and primary and secondary moments after long term losses Open Results Tendon Results 52 LARSA 4D Introductory Training Manual for Bridge Projects This graph which including the short term losses lines initially now shows the tendon forces at the selected result case five years later in green You can also use this window to look at primary and
7. Rotation X cell on the diagonal enter 1e8 Fi Spring Stiffness Matri Abutment Bearing o E Spring 6x6 Stiffness Matrix Translation X Translation Y Translation Z Rotation X Rotation Y Rotation Z kips ft kips ft kips ft kips ft rad kips ft rad kips ft rad 1 0000e8 0 0000 0 0000 0 0000 1 0000e8 0 0000 0 0000 0 0000 1 0000e6 6x6 Stiffness Matrix for the Abutment Bearings e Close the Spring Stiffness Matrix Abutment Bearing window Then close the Properties spreadsheets We will now create two more springs and assign the 6x6 stiffness matrix to the bearings a In the Geometry spreadsheets change to the Springs tab The bearing we created previously will still be there Add two more springs at joints 4 and 5 Ignore the K Tension field this time and instead scroll far to the right and set the Properties Definition fields to Abutment Bearing for both new bearings 15 LARSA 4D Introductory Training Manual for Bridge Projects lates x Springs Mass Elements kS Isolators Bearings Tendons x Lanes x ay eee K Maximum Maximum ction kips ft Compression Tension Compression Hook ft Gap ft Properties Definition P kips ft kips kips ns Z 1 0000e8 1 0000e8 none 6x6 0 0000 0 0000 Abutment Bearing 6x6 0 0000 0 0000 Adding the Abutment Bearings Close the Geometry spreadsheets window The graphics window should remain a The model
8. after the bearings have been added Refining the Model Before running an analysis it is important to break up long member elements into small pieces Displacements are computed only at the locations of joints in the model so it is necessary to put joints at intermediate locations on each span We will use the Break Members tool to break the span members into smaller pieces The Break Members tool operates on selected geometry only Use the Modify Break Members tool to break the two selected members in the model into 10 pieces each Enter 10 for the number of segments and then click OK Apply Transformation Break Selected Members Segments 10 Break Points 0 0 to 1 0 from start 0 10000 0 20000 0 30000 0 40000 Loads will be split among broken members Help Cancel Breaking Members For More Information please refer to the following documentation e For model geometry reference see Geometry in LARSA 4D Reference Manual For more on using spreadsheets see Using the Model Spreadsheets in LARSA 4D User s Manual e For help with drawing commands see Drawing Geometry and Loads in LARSA 4D User s Manual e LARSA Section Composer in LARSA Section Composer Manual Spring Property Definitions in LARSA 4D Reference Manual 16 LARSA 4D Introductory Training Manual for Bridge Projects Self Weight Dead Load In this section we will create a static load case for self weight o
9. and off in this process If you turn Complete Rendering off you ll see that the members are drawn in the wireframe diagram also with something going on When Complete Rendering off is off the members are drawn at their centroids Because of the non prismatic variation the member lines no longer touch the joints perfectly as the location of the centroid varies along the member Goto Draw From Selected Geometry Span ei Have spans be included in the graphical display of the structure by opening Graphics Show and making sure Spans is checked The span will be depicted by a bolder green line through the members in the span ss Turn Complete Rendering back on The linear variation has been reworked to range across the entire span rather than repeating member by member The linear variation now correctly runs the length of the first span s Make a span for the second span Unselect All then use the Draw menu tool again In the second span the linear variation is probably going in the wrong way for what would make the most sense To reverse the direction of the variation on just the second span a second cross section definition would need to be created with a different formula The direction of the member elements could also be reversed in the second span but we recommend keeping all member local axes pointed in the same direction so that the sign convention for results is consistent throughout the model However
10. cumulative displacements It can be used with any result type and can be found in the results spreadsheets as well Special tools are also available specifically for tendons e Make sure the final tendon stressing activity step is selected in the Analysis Results Explorer 45 LARSA 4D Introductory Training Manual for Bridge Projects Activate Results Tendon Results The Tendon Editor will open to the Forces amp Losses tab If this were a Time Dependent Staged Construction Analysis the graph would show both short term as well as long term losses due to steel relaxation and superimposed loads e Change to the Primary amp Secondary Moments tab Then choose Mz This graph shows the primary moments in the model along the girder Secondary moments are also available 21000 18000 15000 12000 9000 6000 3000 0 0 00 20 00 4000 6000 38000 10000 120 00 140 00 160 00 1380 00 200 00 Position Along Span ft Tendon Primary Moments Close the Tendon Editor There are also several tendon specific results spreadsheets for reporting forces and primary and secondary moments Goto Results Spreadsheets Tendon Forces Primary Member Ends This spreadsheet reports tendon forces at the start and end of each member along the tendon path including the tendon tensile force and the primary force in the member local coordinate system directions We will add time dependent material effects in the next section of th
11. ee Create a new lane using Draw From Selected Members Lane A new lane is created riding on the top of the cross section surface It appears as a line above the member elements If you cannot see the lane open Graphics Show and ensure Lanes Surfaces is checked Display Objects Display Icons Labels Geometry l Miscellaneous F Joints Joints IV Members vV Supports V Plates _ Slave Masters _ Input Loads V Springs V Isolators V Coordinate Systems _ Analyzed Loads Members _ Vv Areas V Masses Tendons Offse V Construction Grids V Lanes Surfaces lanes Members v 100 Graphics gt Show 293 LARSA 4D Introductory Training Manual for Bridge Projects Go to the Model Data Explorer by clicking Model above the explorers Then switch to the Lanes panel instead of Joints or Members it should read Lanes at the top Right click the new lane and rename it to Right Lane We need to offset it by 6 ft in the global y direction The lane path is defined relative to the members the load is applied to and offsets will be specified in local member directions Global y corresponds to member z The lane path is also specified in inches units as per the initial choices in this tutorial so the offset will be 72 inches in the z direction as you may recall from the display of the cross section in Section Composer e Right click the lane in the explorer and choose
12. elements appear deformed ensure they are selected use Select All and that the correct stage is selected in the Construction Stages Explorer use the View Full Model button in the explorer if necessary The deformations over time are of course also available in the spreadsheets We can also make a displacement over time graph Goto Results Graphs e Change Data Set to Construction Stages ee Change the X Axis type to Days Change the Y Axis result to Joint Displacements and Translation Z and set the Joint number to 10 which is the midpoint of the first span ee Click Update at the top of the window to draw the graph The graph shows that as a result of time the joint is displacing downward more and more The graph shows a stepping function because of the way material time effects are evaluated in each stage The effects of creep shrinkage and other effects are assessed separately within the same day of construction Each has a small but instantaneous effect resulting in several steps straight down ol LARSA 4D Introductory Training Manual for Bridge Projects Fi Graph Construction Stages Days vs Joint Displacements Data Set Construction Stages Days vs Joint Displacements o Construction Stages hd X Axis in Case Index Invert Days Log Scale Result Data Joint Displacements Y Axis int Displacements Translation Z Invert Log Scale l
13. have set this spring to act in the vertical direction Fi Geometry Springs Joints Members Plates Springs Mass Elements Isolators Bearings Tendons Lan Maximum Tension kips K Tension kips ft 1 0000e8 Compression kips ft 1 0000e8 I Joint J Joint Type Direction none Linear Trans Z Adding a Bearing Abutment Bearings The abutments will also be supported using bearings The bearings at the abutments will restrict the deformation of the bridge in all directions of translation as well as in the direction of axial rotation It is important to make sure that any model has no rigid body motions by including enough restraints to prevent uncontrolled motion The restraints described so far are enough to prevent rigid body motion The bearings are connected at the bottom of the girder s web However the joints in the model have been placed at the girder s centroid It is necessary to place a joint at the bottom of the web and connect it to the centroid using a rigid member element We can find out the distance from the centroid to the bottom of the web using LARSA Section Composer Start LARSA Section Composer and open the database created by LARSA 4D earlier basic bridge example sections You should leave LARSA 4D running in the background Click inside the T shape to activate it In the Shapes explorer in the right side of the scre
14. investigate must have a stage even if the stage has no construction steps or construction activities in it Add four new stages by adding rows to the spreadsheet e Set their names to 75 Days 200 Days Two Years and Five Years Set their Construction Days to 75 200 730 and 1800 49 LARSA 4D Introductory Training Manual for Bridge Projects BE Construction Stages Construction Stages i oO x Construction Stages Stage Steps x Stage 1 64 0000 75 Days 64 0000 200 Days 200 64 0000 Two Years 730 64 0000 Five Years 1800 64 0000 Show Only Selected Objects Setting Construction Days ex Close the spreadsheet Open the Construction Stages Explorer and note how it has been updated with the new stage data at the bottom These stages do not need construction steps because the only activities within these stages are automatically created by the analysis engine Running the Analysis Next we prepare to run the analysis Goto Analysis Staged Construction Analysis Choose the Time Dependent analysis type Open the Construction Stages options tab and set Ending Construction Stage to the last stage Day 1800 Five Years Run Staged Construction Analysis Y I E A oe eee Solution Convergence Standard Construction Stages Staged Construction Options Time Dependent Analyze Starting Construction Stage Day 30 Stage 1 v Close Ending Cons
15. it is unselected Model Load Group Stage Results m B o i Construction Stages Ej AddStage rfAddStep X 3 View Full View Struc Load Activ enno Model Stage 1 day 30 HI First Segment Span 1 Segment 1 Self Weight f 1 00 E s a ay oh oes The View Full Model Button For More Information please refer to the following documentation e Structure Groups Explorer in LARSA 4D User s Manual Loads in LARSA 4D Reference Manual Staged Construction Analysis in LARSA 4D Reference Manual 40 LARSA 4D Introductory Training Manual for Bridge Projects Tendons Tendons are used to model pre and post tensioning of internal and external tendons We will demonstrate a post tensioned internal tendon in this tutorial with the following profile Cn l TTF TATE 2 SS Hee ee nn Final Tendon Profile Creating Tendon Geometry The easiest way to create the tendon path is to let LARSA 4D create one from the selected members Then the tendon can be fine tuned using the tendon path spreadsheet This follows a similar process as creating a lane The only elements in this model are the members the tendon will pass through e Select All Use the command Draw From Selected Members Tendon The Tendon Editor will open with a side view of the tendon The tendon is currently a straight line running along the section centroid We will alter the tendon so that i
16. of Staged Results Tendons Creating Tendon Geometry Setting Tendon Properties Stressing the Tendon Tendon Results Time Dependent Material Effects Choosing the Design Code Setting Material Properties Casting and Construction Day Running the Analysis co 11 11 11 12 13 16 17 19 23 23 25 26 28 30 33 33 34 35 38 39 41 41 43 45 45 47 47 48 49 50 LARSA 4D Introductory Training Manual for Bridge Projects Results Haunches Creating a Non prismatic Section Spans Simple Parabolic Variation of Depth Piecewise Variation 51 55 55 57 58 58 LARSA 4D Introductory Training Manual for Bridge Projects Introduction About This Manual This tutorial provides an overview for using LARSA 4D for the analysis of a straight two span single girder bridge The bridge consists of a T shape cross section The example bridge in this guide consists of a T shape cross section It has two spans of 100 feet each The abutments are modeled as bearings supporting translation and rotation The pier is modeled as a bearing supporting vertical displacement only m 100 ft 7 Pier i Abutment spring Bearing spring in z Abutment spring c 100 ft A Two Span Bridge The cross section will be a T shape as given below rf tw 36 Girder Cross Section units inch Key Concepts In the first half of this guide we will create the LARSA 4D model by e Setting project unit
17. the Construction Stages Explorer where it says No Property in the figure it will now read Loading Factor and the field below it will have 1 Change this to 1 and click the checkmark to apply the change as Do the same to the three other load removal load cases Temporary Load 4 f 1 00 Joint 19 All DOF Free I I Remove Temporary Loads 2 4 Temporary Load 3 f 1 00 Temporary Load 4 f 1 00 Loading Factor 1 Removing Temporary Loads Y Running the Analysis We can now run the Staged Construction Analysis The analysis will compute the state of the structure after each construction step Goto Analysis Staged Construction Analysis Click Analyze ee After the analysis completes close the analysis window The Analysis Results Explorer will open automatically This time the result cases are in the Construction Stages group Inside this group there will be a group for each construction stage we have just one and inside that the results for each construction step Open up the result groups and click the result case Stage 1 First Segment 38 LARSA 4D Introductory Training Manual for Bridge Projects Select result cases to view from the list below Load Cases Load Combinations Construction Stages Stage Stage 1 Stage 1 First Segment Stage 1 Second Segment Stage 1 Remove Temporary Stage 1 Third Segment Stage 1 Fourth Segment Stage 1 Remove Temporary Moving Load
18. the time points where results are desired Running the analysis Evaluating the cumulative incremental and partial results due to time dependent changes Choosing the Design Code Time dependent effects must be turned in two ways First we choose which time dependent effects to include in the analysis and according to which code those effects should be computed Goto Analysis Time Dependent Analysis Options Select CEB FIP 90 as the code and check all of the options to include all time dependent material effects in the analysis Time Dependent Analysis Options Creep amp Shrinkage amp Time Effect on Modulus n OK J Include 7 Include Include Time o Creep Shrinkage Effect on Modulus Code For Creep amp Shrinkage CEBFIPSO v Cancel Tendon Stress Losses 7 Include Steel 7 Losses due to Creep Relaxation Shrinkage SI Loads Time Dependent Analysis Options AT LARSA 4D Introductory Training Manual for Bridge Projects Setting Material Properties We will first indicate which materials in the model are subject to time dependent behavior By default no material is subject to time effects We will create Material Time Effect definitions and assign those to the materials to indicate that they will undergo time effects Material Time Effect definitions are used to enter properties such as a creep coefficient and time versus elastic modulus curves These fields are
19. to 50 You can see the preview of the section update at the lower left of this window ee Click Close to apply the change to the cross section definition Go back to the graphics window Turn on Graphics Complete Rendering This saw tooth pattern is clearly not what was desired The linear variation is repeated within each member This is because LARSA 4D does not know what the linear variation should range over a single member a few members a whole span or the entire girder We must tell LARSA what to do The sawtooth pattern is corrected next 56 LARSA 4D Introductory Training Manual for Bridge Projects In this case we will want to segment the girder into the two spans In the final setup for the haunches we will have the non prismatic variation apply span by span that is repeating after the pier Spans To tell LARSA 4D what members the variation should range over we create what are called spans These spans in LARSA 4D do not necessarily need to correspond to a span in the bridge e g from pier to pier they are just a tool to identify a range of contiguous member elements In this case though we do want the spans to match the two spans in the model The easiest way to create spans is to select the members that form a single span and then use a tool to create a span from the selected members Unselect All and then select just the members in the first span It may help to turn Complete Rendering on
20. AINING MANUAL AN INTRODUCTORY GUIDE FOR BRIDGE PROJECTS LARSA 4 THE COMPLETE SOFTWARE FOR BRID LARSA 4D Introductory Training Manual for Bridge Projects A manual for LARSA 4D Finite Element Analysis and Design Software Last Revised February 2013 Copyright C 2001 2012 LARSA Inc All rights reserved Information in this document is subject to change without notice and does not represent a commitment on the part of LARSA Inc The software described in this document is furnished under a license or nondisclosure agreement No part of the documentation may be reproduced or transmitted in any form or by any means electronic or mechanical including photocopying recording or information storage or retrieval systems for any purpose without the express written permission of LARSA Inc LARSA 4D Introductory Training Manual for Bridge Projects Table of Contents Introduction About This Manual Getting Started Properties Material Properties Cross Section Properties Geometry Joints Members Pier Bearing Abutment Bearings Refining the Model Self Weight Dead Load Linear Static Analysis Influence Line Live Load Analysis Preparing the Influence Coefficients The Lane Preparing the Influence Coefficients The Load Case Vehicle and UDL Setup Accessing Results Combining the Left and Right Lanes Staged Construction Analysis Structure Groups Construction Loads Construction Stages Running the Analysis Getting Out
21. Each category can make use of different units for convenience Coordinates are often entered in meters or feet while sections are often specified in inches or centimeters The Units window is arranged in a grid with the unit categories arranged vertically and the unit types length force temperature horizontally Set the units to be used in the project with the Input Data Units command The units should be as indicated in the figure below If any changes need to be made choose Apply Conversion Units Input Units Length Unit Force Unit Temperature Unit rare Coordinates feet ft v Section inches in hd Material inches in Pound ib Fahrenheit F v Spot Conversion Loads feet ft v Kips kips Fahrenheit F v Change Labels Springs lsolators feet ft Kips kips X ance Mass feet ft gt Kips kips x 7 elp Units Set up initial visual display options in the Graphics Show command which controls which aspects of the project model are included in the graphics view Be sure Joints Members Springs Tendons Lanes and Supports are turned on Graphics Display Options Display Objects Display Icons Labels Geometry Miscellaneous Joints Joints v Members V Supports v Plates Slave Masters 4 Input Loads 7 Springs Isolators v Coordinate Systems Analyzed
22. Edit Path amp View A spreadsheet window on top for the path and a special lane graphics window below will open Each row in the path spreadsheet specifies a control point on the lane path The lane is made up of the straight line segments between the control points It is also possible to create a smoothly curved path Change the Offset Z to positive 72 for all rows It will help to use the spreadsheet edit toolbar tool to change all of the cells at once Fi Lane Path lt Right Lane gt fo fe Iss Lane Path Geometry Reference Object or Range Offset Y rer Z X Reference J Reference Object Offset X Point Type Type ft Y Reference Z Reference geometry member Y1 Local Edge Reference Line m geometry member 5 0 0000 72 0000 Start Y1 Local Edge Reference Line geometry member 6 0 0000 72 0000 Start Y1 Local Edge Reference Line geometry member 7 0 0000 72 0000 Start Y1 Local Edge Reference Line geometry member 8 0 0000 i 72 0000 Start Y1 Local Edge Reference Line geometry member 9 0 0000 I 72 0000 Start Y1 Local Edge Reference Line geometry member 10 0 0000 f 72 0000 Start Y1 Local Edge Reference Line 4 pijit Decimals Right Lane Setup In order to comply with the part of the loading specification that says that in the two trucks case each truck must be on a different span we must tell LARSA 4D where the break is between the spans We do this
23. Loads v Areas Members Masses Spans v Tendons Offsets V Construction Grids v Lanes Transparency Members 7 100 a The Show Command For More Information please refer to the following documentation e Model Units in LARSA 4D User s Manual e Graphics Display Options in LARSA 4D User s Manual 7 LARSA 4D Introductory Training Manual for Bridge Projects LARSA 4D Introductory Training Manual for Bridge Projects Properties Before starting on the geometry of the project we will bring in material and section properties to assign to the girder and later the post tensioned tendon Material Properties s Inthe Input Data menu click the Materials tool It is shown below Standard Materials Steel A992 eet Modulus of Elasticity 2 9e7 Ibir A529 Shear Modulus 1 12e7 Ib in A572 G42 AES 4572 G50 Unit Weight 0 28357 Ib ir A572 G60 Thermal Expansion 6 5 1 F 10 6 4572 G65 A5SS Yield Stress 50 000 Ib ir 4615 G40 3 7 AB15 GE0 Fu or fc28 65 000 Ib ir 4615 G75 Tendon GUTS 0 A OB m2992 _ Cement Hardening Type Not Concrete Open Custom Database Help Cancel Importing Standard Materials The materials tool presents a database of common material properties They are not available for use until they are imported into the project s Make the Steel category selected and choose a steel material appropriate for the strands
24. Manual for Bridge Projects The two new joints 4 and 5 must be connected to the joints at the centroid joints 1 and 3 using rigid connections ae Change to the Rigid Links sub tab ee Add two rows to the spreadsheet and connect joints 4 to 1 and joints 5 to 3 If bearings act in multiple directions it is possible to put multiple grounded springs at a single joint each acting in one direction or a single grounded spring with a 6x6 stiffness matrix can be used to define its stiffness in all directions at once We will use a 6x6 stiffness matrix Open the Properties spreadsheets from the Input Data menu and change to the Spring Properties tab Adda new row to the spreadsheet Name the new spring property definition Abutment Bearing Change its type to 6x6 Stiffness Matrix Then right click the row and choose Edit Stiffness Matrix The spreadsheet that appears allows you to edit the 6x6 stiffness matrix for this element Stiffness matrices are symmetric matrices that represent the relation between displacement and force Each cell represents essentially a spring constant relating one direction of displacement with one direction of force For basic springs only the diagonal cells are used The off diagonal cells are left as zero Because the matrix must be symmetric the cells below the diagonal cannot be edited The diagonal cells are the bottom most editable cells In the three Translation cells on the diagonal and the
25. UDL 158 9257 eee 368 0 0000 700 5923 1 6 Right Lane 170 4 UDL 87 6273 AFEN S 409 0 0000 425 9005 1 6 Right Lane s37 89 UDL 77 2326 48 9911 0 0000 447 4382 0 0000 504 2109 Numerical Influence Results and the Context Menu It is also possible to right click a row in an influence analysis spreadsheet and use either the Create Input Load Case or Create Result Case commands to create a new case that contains the loading configuration that produced the effect shown in the chosen row Creating an input load case creates a new load case with member or plate loads for the vehicle axles and UDL Creating a result case makes a new linear result combination out of the already analyzed unit load result cases It is then possible 28 LARSA 4D Introductory Training Manual for Bridge Projects to inspect either new case or re analyze an input load case to obtain the static results for the loading configuration The graphical influence coefficient view is the recommended method to inspect the loading configuration that maximizes a result somewhere on the structure e Make sure you are at a graphics window with member sectional forces displayed Click the Influence Coefficients button in the floating graphical results options tool window Incremental Animate Influence CAS Plate Torsion Mxy Envelope Max View Full Cumulative Results i yy Type Ext Influence Coefficients Mode Once this tool is o
26. anteed ultimate tensile strength on A992 to 270 000 kips in We can now look at the tendon force profile In the Tendon Editor change to the Forces amp Losses tab to view the short term force losses along the length of the tendon The forces and losses chart shows two curves superimposed The top blue curve shows the forces in the tendon including the wobble and curvature friction coefficients but before anchor set has taken effect The lower magenta curve shows the forces in the tendon after anchor set has occurred Fi Tendon Editor Tendon Geometry Forces amp Losses Primary amp Secondary Moments Tendon 1 Forces Along Tendon Tendon 1 5472 5422 5372 5322 5272 5222 5172 5122 0 00 O 2 c v w 20 00 Force at Jacking Elongation 1st Pull 2nd Pull as Close the Tendon Editor 6 106300449 n a 40 00 60 00 80 00 100 00 120 00 140 00 160 00 180 00 Arc Distance Along Tendon ft Short Term Losses After Anchor Set Tendon Short Term Losses 44 LARSA 4D Introductory Training Manual for Bridge Projects Stressing the Tendon The tendon will not affect the analysis until LARSA 4D is instructed to stress the tendon Stressing tendons can be done as a construction activity in Staged Construction Analysis It is also possible to apply the equivalent member loads due to stressing a tendon as a load case ina standard static analyis but we will not cover that here
27. ctures that have large displacements such as suspension and cable stayed bridges and guyed towers The engine became popular for analyses of these types of structures because of its unprecedented accuracy at a reasonable price The engine has been powerful since day one using both tangent stiffness and the full Newton Raphson method with iterations in nonlinear analysis LARSA software has come a long way since it was first available on the VAX super mini computers decades ago LARSA Inc has always been an industry leader LARSA was the first to offer an individual PC based DOS structural analysis package with geometric nonlinear analysis capabilities in 1986 In 1994 LARSA took the early next step to Microsoft Windows with a point and click graphical user interface and two years later was the first to offer elastic perfectly plastic pushover analysis Today LARSA s flagship product is LARSA 4D released in 2006 and featuring new seismic and inelastic elements major improvements to influence and staged construction analysis and many new features for bridge design and analysis LARSA 4D Introductory Training Manual for Bridge Projects Getting Started We will now begin the tutorial s Open LARSA 4D or if LARSA 4D is already open start a new project ge Save the project such as with the name basic bridge example Units in LARSA 4D come in six categories coordinates sections materials loads springs isolators mass elements
28. d on Click Vehicular Loading e Click Add Lane Type Then click the Select Vehicle Pattern entry in the list on the left On the right where it reads Select Pattern click it and choose HL 93 HS20 44 Design Truck 26 LARSA 4D Introductory Training Manual for Bridge Projects Next we will enter the specification for the tandem condition Click Add Lane Type Set the vehicle for this lane to HL 93 Design Tandem A Lane Type refers to the way a design lane may be loaded The influence line solver will choose the lane type that produces the most extreme effects Click Add Lane Type a third time Set the first vehicle for this lane to HL 93 HS20 44 Design Truck Set the factor to the right of the vehicle type selection to 0 9 Click Add Vehicle A second HL 93 HS20 44 Design Truck with the same factor is added into this lane type s Set the UDL Factor to 0 9 This applies to the current lane type We have not yet set the UDL magnitude Set the minimum back to front spacing to 50 feet And turn on the option One Load Pattern Per Span The One Load Pattern Per Span option pertains to the two trucks lane type in which the two trucks must be placed on different spans The span break markers inserted into the lane path definition control what LARSA 4D knows to be the spans a Verify that your screen looks like the following figure Result Case Name Right Lane HL 93 HS 20 44 Design Truck HL 93 Desigr Stan
29. d simultaneously with a multiple presence factor of 1 0 We will create the simultaneous loading condition first A Linear Result Combination simply sums the numerical results of two or more cases Start the Results Linear Combination tool Add the two influence line cases Left Lane Right Lane into the right list Either double click the influence cases or click a case and then click the big right arrow Click OK Name Class Right Lane Left Lane None v Available Result Cases Moving Load Cases Time History Cases Cases in Group Result Case Extract Load Class A Right Lan 1 All Pushover Cases Left Lan Combo with Moving Load Cases Stage Analysis Scenariofs RSA Modal Influence Based Right Lane Left Lane Linear Combinations X m T Help Combine for Extreme Effects OK Cancel Linear Combination of Two Lanes ee Click the new linear combination case in the Analysis Results Explorer and then open a results spreadsheet to view the combined effect from the two lanes Enveloping the three conditions left right together can be accomplished using Extreme Effect Groups which are like saved envelopes ee Start the Results Group for Extreme Effect tool s Find the three cases for the right lane the left lane and the new linear result combination and add them into the list on the right using the big right arrow in the midd
30. dard Solution Method v General Options Vehicular Loading Unitorn Patch Loading AddLaneType AddVehicle x Denona Vehicle Load Pattern Factor HL 33 HS20 44 Design Truck HL 93 HS 20 44 Design Truck z 0 9 Design Lane HL 93 Design Tandem Max Lanes UDL Factor Design Lane UDL Factor 0 9 No Limit v 0 9 HL 937 H520 44 Design Truck Factor 0 9 HL 93 HS 20 44 Design Truck Factor 0 95 Min Back to Front Spacing 50 ft Design Lane Vehicle Marain o ft Min Side to Side Spacing o ft E One Load Pattern Per Span Help Cancel Influence Based Results Setup ee Change to the Uniform Patch Loading tab and enter a UDL magnitude of 0 64 kip ft ae At the top of the window set the result case name to Right Lane ee Click OK to finish creating this case Then repeat this process for the left lane The Analysis Results Explorer will show a new group called Influence Based with two new result cases inside 2 Influence Based Right Lane Left Lane Influence Analysis Result Cases in the Analysis Results Explorer 27 LARSA 4D Introductory Training Manual for Bridge Projects Accessing Results To access results click the name of the case and use graphical or spreadsheet results While each case individually does not provide the final values necessary for AASHTO LRFD see below they are the first step ee Click the first influence case Right Lane in the Analysis R
31. e Time 1 0000 Improved Class 2 No 2 Steel Time 1 0000 Improved Class 2 No Material Time Effect Definition Right click the row or use the CEB FIP 90 menu and choose Edit Curve Stress GUTS VS Relaxation Verify that the default curve is acceptable ee Close the curve spreadsheet Right click the Steel Time row again or use the CEB FIP 90 menu and choose Edit Curve Time VS Relaxation Verify that this default curve is acceptable The coefficients for the two curves are combined multiplicatively e Close the curve spreadsheet window Go to the materials spreadsheet by clicking the Materials tab e Change to the More Properties subtab s For the A992 and Fc_4 materials change the Material Time Effect column to Steel Time and Concrete Time respectively 48 LARSA 4D Introductory Training Manual for Bridge Projects Note that the Concrete Cement Hardening Type is set to Normal for this material versus Not Concrete for the steel material indicating Fc_4 is concrete and subject to time effects These options came from LARSA s material database e Close this spreadsheet window Casting and Construction Day Earlier we said that each stage represents a day of construction For the Time Dependent Staged Construction Analysis the day of each stage which we must set impacts the material properties of the members and of the tendon A casting day must also be set for each concrete member undergoi
32. e lumped on the centerline of the lane so no transverse effects are considered e HL 93 Design Tandem in conformance with AASHTO LRFD 3 6 1 2 3 The design tandem consists of a pair of 25 kip axles spaced 4 ft apart The uniform load UDL is specified separately from the vehicle type We first must load into the project the vehicle definitions from a database of vehicles provided with LARSA 4D Goto Input Data Connect Databases and choose Connect Standard Database Open the file AASHTO Vehicle Patterns dml Then click OK Connected Databases Connect databases to your project to use load patterns time history and response spectra curves parametric sections and other external data in pour analysis Linked Databases Disconnect s4 C Prog AASHTO Vehicle Pattern Load Patterns 8 I C User ridge example sections lpsx Parametric Sections Edit Connect Database Connect Standard Database Connecting the AASHTO LRFD Load Patterns Database Each lane will be configured separately For each lane we will create an Influence Line result case which specifies how to perform AASHTO LRFD live load Click Results Influence Line Surface Case to start configuring a new influence based result case ee Make sure that Influence Line Coefficients Right Lane is chosen at the top All of the default options on the first tab are correct Note that Load for Extreme Force Effects is turne
33. ease refer to the following documentation e For more information on creating non prismatic variaton see Nonprismatic Variation in LARSA Section Composer Manual e For more information on the LARSA formulas language see Parameters and Formulas in LARSA Section Composer Manual 59 LARSA 4D Introductory Training Manual for Bridge Projects 60 LARSA 4D Introductory Training Manual for Bridge Projects Index AASHTO LRFD 23 bearings 11 break members 11 bridge example casting day 47 CEB FIP 78 90 47 combinations 23 construction loads 33 dead load 17 deformed model 19 drawing members 11 example erounded springs 11 groups 33 GUTS 47 haunches 55 influence line example 28 jacking a tendon 41 joints spreadsheeet 11 linear static analysis 19 live load example 23 non prismatic variation 55 post tensioning example 41 refining a model 11 results 19 scale factor 19 self weight 17 staged contruction analysis example 33 stress versus GUTS 47 stressing a tendon 41 structure groups 33 temporary loads 33 tendon editor 41 tendons 41 time dependent material effects 47 training manual 61
34. ection Unit in Single T Bridge Beam Use LARSA Section Composer to find the location of the bottom of the T section relative to the centroid Close Section Composer a Back in LARSA 4D return to the joints spreadsheet by clicking the Joints tab The member reference y axis corresponds to the global coordinate system z axis That is because the member s orientation angle was set to 90 degrees Also note that the joint coordinates units is feet in the spreadsheet not inches as shown in Section Composer ee Add a new row to the spreadsheet ex In the new rows Z cell type 52 9 12 without the quotes Simple formulas can be entered into LARSA 4D spreadsheets although unlike in Excel the formulas are not saved The value 4 4083 will be computed and then entered into the spreadsheet This creates a joint at 0 0 4 4083 Add another row to the spreadsheet to create a joint at 200 0 4 4083 Joints Members Plates Springs Mass Elements Y Isolators Bearings N Tendons l Joints Slave Masters Rigid Links Rigid Diaphragms Translation Rotation DOF eee 0 0000 0 0000 0 0000 all free all free Global 100 0000 0 0000 0 0000 all free all free Global 200 0000 0 0000 0 0000 all free all free Global 0 0000 0 0000 4 4083 all free all free Global 200 0000 0 0000 all free all free Global The joints spreadsheet after adding the bearing joints 14 LARSA 4D Introductory Training
35. ectra Case i A Incremental Post Analysis Case Spreadsheets BETA gt Hb influence Coefficients Graphical Results Toolbar Pro Ae Se a Graphical Results Menu and Toolbar 19 LARSA 4D Introductory Training Manual for Bridge Projects Select all elements using Selection Select Objects Select All Results are only shown for selected elements Drag up the scale factor slider until you can see deformation The slider is at the bottom of the Analysis Results Explorer Scale factor 8 peevecencceccsccnssescoesscessoneccsensescesesocessonsocsosooevessonsocsonsoovessosvossesecesssosesescosoeecsaoee Graphical Results Scale Factor Reaction labels can be turned on from the floating Graphical Results Options tool window 223 27 610 39 266 09 266 09 Deformed Model Turn off graphical results by choosing None in the graphical results menu or toolbar Open the stresses spreadsheet using Results Spreadsheets Member Stresses The stresses spreadsheet shows stresses at pre set locations on the perimeter of the cross section called stress recovery points Four stress recovery points have been pre set for the T shape at the four extreme corners Stresses are shown at segments within each member element The number of segments to divide each member into is controled in Results Results Display Settings Fa Member Stresses L Envelope Selected Result Cases Incremental Result
36. egment 1 STIFFNESS amp WEIGI Temporary Loads 1 Add Group Add Load Case Second Segment Self Weight Span 1 Segment 2 STIFFNESS amp WEIGI Temporary Loads 2 Add Group Add Load Case Remove Temporary Loz Temporary Loads 1 Temporary Loads 2 Add Load Case Third Segment Self Weight Span 2 Segment 1 STIFFNESS amp WEIGI Temporary Loads 3 Add Group Add Load Case Fourth Segment Self Weight Span 2 Segment 2 STIFFNESS amp WEIGI Temporary Loads 4 Add Group Add Load Case Remove Temporary Loz Temporary Loads 3 Add Group Temporary Loads 4 Add Load Case Y Add New Stage Add New Step to Stage 1 Construction Stage Loading Now we will add and remove temporary supports In the First Segment step we will add a temporary support at joint 9 In the Second Segment step we will remove the support The same will occur for joint 19 in the Third Segment and Fourth Segment steps ee Change to the Support Activity tab Double click the first Add Activity label and replace it with 10 Press enter Set its Translation Z to Fixed e Double click the Add Activity label beside the Second Segment step and replace it with 10 again Press enter This time its Tranzlation Z will be free the default Do the same to fix Translation Z for joint 19 in the Third Segment step and the free it in the Fourth Segment Step i Stage Steps Load Cases Structure Groups Support Activity Slave Master Activity Tendon Activi
37. elative Span Position 0 to 1 recomended Absolute Length from Span Start in Parameters gt Single T Bridge Beam d 72 0000 Editing Section Parameters This command available for parametrically defined sections only opens a window which can be used to modify the parameters we initially set for the section The T shape section as with most other custom parametric sections provided with LARSA 4D is defined with a depth parameter that makes it easy to have the depth of the section vary along the length of a span When we change the depth parameter the top surface of the flanges remains in place while the bottom of the web moves up and down relative to the member reference axes and thus the rest of the LARSA 4D model In this window we can enter numeric values for parameters but we can also enter formulas using a special x variable This variable represents the position on the span It has the value zero at the start of the span and depending on how we proceed it can range from 0 0 to 1 0 along the span or it can have actual length values from 0 0 to the length of the span To create non prismatic variation we enter a formula for the depth parameter d in terms of the x variable ee Change the value for the d parameter from 72 to 72 22 x This is a formula for linear variation If x varies from 0 0 to 1 0 then the depth of the section will vary from 72
38. embers In the Model Data Explorer on the right hand side of the screen choose the appropriate section Girder T Section and material Fc_4 for the girder Also set orientation angle to 90 degrees which is the usual convention for horizontal members No other fields in the Model Data Explorer need to be set now e Click the leftmost joint and then release the mouse button to start drawing a member from that joint Then click the middle joint to complete drawing the member for the first span e Click the middle joint and then the rightmost joint to create the member for the second span The members are created with the section material and orientation angle we chose a M Load Grou Results WF Graphics View1 todel p Stage esu Members 5 Global XZ A oQ Drawing Members using the properties below x Point To Point ID amp Span Joints a a ID ft i a C Length eias l i Start Joint Direction 45 End Joint Increment 0 00 ft Properties Break 1 Type Beam X Section Girder T Section v OSEE s End Section same as start v Material Fe_4 X Angle 90 0000 Rigid Zone x L From Start 0 0000 From End 0 0000 Miscellaneous kips Prestress Force 0 0000 End Releases Drawing Members ex To end the drawing operation close the floating Draw Members window by clicking on its X close button Check that the members have been set up correctly using Graphics
39. en change to the Points tabs Then change Edit Local to View Global The View Global option shows the location of the points on the perimeter of the shape in the member reference coordinate system which in this case is aligned with the member centroid Note the direction of the member reference axes in the graphics view of the cross section Member Y is up The member reference axes differ from the global coordinate system axes 13 LARSA 4D Introductory Training Manual for Bridge Projects se Make sure Show Point Numbers is turned on in the View menu Then identify a point number at the bottom of the web point 5 or 6 and in the points spreadsheet note the points y coordinate 52 8608 in Hj LARSA Section Composer basic bridge example sections ipsx File Edit View Section Shape Help Dad o QQQAQQH RIK BRB Algo rete wes bass Uo ead Girder T Section 41 7484 in 89 1374 in T es Cs Fs a a O 0 a 2 E E w A a w f 701 270 126 46 102 0 l 192 311 Member Y 19 4467 65 5549 50 334 1 158 292 6 444 00 Cty The distance from the top of the section to the centroid A Parameters Points Rebars Member Z SCH I Mee View Global v 0 0000 19 1397 144 0000 19 1397 144 0000 7 1397 24 0000 1 1397 18 0000 4 8603 18 0000 18 0000 528603 18 0000 4 8603 Currently available parameters are d b tw tf tf2 Id Ib Girder T S
40. esults Explorer s Turn on graphical member force diagrams and change the report to Moment Mz This graph represents the envelope of forces for all possible positions of the truck tandem or two trucks plus lane load including variable axle spacing D az b Moment Mz a View Full Cumulative Results Moment Diagram Accessing results in the spreadsheets works as usual except you must choose an envelope column In this case you would choose the Mz column to envelope on The rows of the spreadsheet then show the min and max Mz values for each station along the girder plus corresponding forces in the other directions Mz refers to member local coordinate system directions You may check where LARSA 4D decided to place the truck and lane load to produce the extreme effect for any point on the structure using several methods The first method is to look at the Result Case column on the spreadsheet It indicates the station number in coordinate units from the start of the lane at which each vehicle is placed refering to the front of the vehicle gum 2UM SElECtTEd Lells Min Max for Moment Z kips ft Min Max x JABS v Select Objects jhi Unselect Objects p pnt kips Select Special Moment Moment Result Case kips ft kips ft 1 1 Right Lane s28 s200 UDL 0 1465 lt 062 0 0000 0 6457 reate Input Load Case 1 1 Right Lane s54 s174 6
41. he effects of arbitrary complex load patterns on design lanes Influence based results are often necessary to comply with bridge design codes such as the AASHTO LRFD which requires finding the worst case scenario out of more possibilities than can be analyzed individually LARSA 4D supports both influence lines and influence surfaces Influence lines is used on models where girders are represented by linear elements whereas influence surfaces is used on models with a deck surface modeled as plate elements In this section we will use influence line analysis to find the worst case truck positioning according to AASHTO LRFED There are two parts to influence analysis The first part determines how the influence coefficients i e unit loads are computed on a lane on the bridge The second part specifies vehicle and uniform load options according to a design code Preparing the Influence Coefficients The Lane A lane in LARSA 4D is a linear path in the model along which a vehicle pattern or unit load will march in a moving load or live load analysis A lane can take any path through 3D space If it falls off of a girder the loading will cause moments For an influence line analysis we must place a lane on the structure where a traffic lane will fall Because our cross section is 24 ft wide two 12 ft lanes will fit one 6 ft offset to the left y side and one 6 ft offset to the right y side We will start by creating the right lane
42. he segment is first constructed and will be removed when the entire span is complete To identify the members we will place the temporary loads on use the Pointer mouse tool The Pointer tool is the fourth tool the one to the left of the selection tool in the figure above showing the graphics mouse tools Turn on the Pointer tool and hover over the middle member in each segment Hold the key while hovering the mouse over the members to see the member numbers or look in the status bar at the bottom of the screen The members should be 4 9 13 and 18 Identify the two joints where we will need temporary supports between the segments The joints should be 10 and 19 34 LARSA 4D Introductory Training Manual for Bridge Projects An alternative way to identify member numbers is to turn on member number labels This can be done with Graphics Show or the keyboard shortcut NA which cycles through number label options Press N once for joint numbers and again for member numbers Then press it again to cycle to spring numbers and again to turn off number labels Open the Load Cases Explorer by clicking Load above the Structure Groups Explorer Then create four new load cases named Temporary Load 1 2 3 and 4 Double click the first load case for temporary loading and switch to the Member Loads tab Add a row to the spreadsheet Set the member to 4 the direction to Global Z and the magnitude to 100 kips A
43. idge Projects Staged Construction Analysis Staged Construction Analysis is a 4D analysis What is meant is that the analysis models changes to the structure over time In this manual we will create a basic setup for staged construction using construction and loading activities In this section we will set up the basic construction sequence In the next section we will add a post tensioned tendon and a tendon stressing activity The construction sequence will be in four steps from left to right The first construction step will construct half of the first span with a temporary support at mid span and a temporary construction load The second construction step will assemble the second half of the first span add a second temporary load and remove the temporary support The third construction step removes the temporary loads This will then repeat for the second span Temporary Loading 100 100 100 100 Temporary Temporary Support Support Span 1 Segment 1 Span 1 Segment 2 Span 2 Segment 1 Span 2 Segment 2 Step 1 Step 2 Step 3 Step 4 The Construction Sequence Structure Groups In order to run a Staged Construction Analysis we will need to first define structure groups which group the parts of the structure together that will be assembled together The first group will be the left half of the first span e Open the Structure Groups Explorer by clicking the Group button above the explorers Unselect everyth
44. ie Lett Right Offset from Reference Position x D ft uF 5 in Z 0 from Start Y3 Axis m x member 15 10 0000 150 0 From Start ft Tendon Curvature Type n a n a Comer 0 0 Cover gt 5 00000in Delete Point Tendons in View New Tendon X Update Tendon Editor It is also possible to make the tendon smoothly curved LARSA 4D has several tendon curve options The first option creates a curve at a vertex on the path by rounding out the vertex with the arc of a circle of a given radius After rounding out the vertex the original geometry control point no longer falls on the tendon path This is illustrated in the figure Circular Radius PI Point Specified Member Side View Tendon Circular Curve Fitting Click the first geometry control point we added in member 7 to select it ee At the lower right of the tendon editor change curvature type from Corner to Circular Radius Enter a radius of 200 feet Click Update Note how the tendon diagram has updated with the new curved path Another curvature method is to create a parabolic curve by specifing the tendon s direction tangent at the control points This requires setting the curvature method to parabolic on the two geometry control points surrounding the curved segment At each geometry control point a Y Angle and Z Angle are set for the tendon s profile in the member s local y and z planes The angle is e
45. in the design we actually want the variation will be symmetric within each span so we will not need to create a second cross section In the next step we will revise the variation so that we get haunches at the abutments and pier The next time you save the project you will be asked to recompute the torsion constant J This constant needs to be recomputed now for each member because the cross section properties now differ in each member 57 LARSA 4D Introductory Training Manual for Bridge Projects Simple Parabolic Variation of Depth To create the haunch described at the start of this section consider the variation that we want within a span At first there will be parabolic variation in depth from 72 inches to 50 inches over 20 feet Over the next 60 feet the depth will remain constant at 50 inches Then from 80 feet to 100 feet the parabolic variation will repeat in reverse from 50 to 72 inches This requires us to define a piecewise variation function Before we create a piecewise definition we will apply a simple parabolic function that has the depth vary from 72 inches at the sides to 50 inches mid span Return to the Edit Parameters window by going to the sections spreadsheet and then right clicking the section row You may notice that in the spreadsheet the section no longer displays its properties This is because the properties vary depending on position We could revise the formula here and enter a second order polyn
46. ing using Selection Unselect Objects Unselect All or any other method s Using the selection mouse tool shown below drag a window to select the grounded spring for the left abutment and the first five members on the girder Selection Tool You should see the following after you have made the selection 33 LARSA 4D Introductory Training Manual for Bridge Projects e 4 The First Structure Group Click the Add Group button in the Structure Groups Explorer to add a new group for the selected structural objects The new group automatically contains the currently selected members and joints but this will not be relevant Click on the group and rename it to Span 1 Segment 1 Do the same for the remaining three segments Unselect All window select the segment add a group and then rename the group Include the pier in Span 1 Segment 2 and include the right abutment in Span 2 Segment 2 Model Load Group Stage Results o fj Add Folder Add Group Bt Auto Span 1 Segment 1 Span 1 Segment 2 Span 2 Segment 1 A Span 2 Segment 2 Structure Groups se When you are done select all geometry Construction Loads Each condition of temporary or traveler construction loading must be defined as a load case We will create four temporary loading conditions which will be point loads at the mid point of each girder segment Each temporary load will be applied when t
47. ion Analysis unless it is explicitly included as an activity A self weight load case should be applied in any step in which elements are constructed as in this case Self weight will be applied to all and only the newly constructed elements It should not be applied in other steps e Click the drop down arrow next to Add Load Case besides the first construction step and choose Self Weight Simultaneously we will apply the first temporary load e Click the drop down arrow next to Add Load Case below Self Weight and choose Temporary Load 1 For the Second Segment step do the same add the Span 1 Segment 2 group self weight again and Temporary Load 2 To remove the temporary loading in Remove Temporary Loading 1 we will apply the same load cases again but with opposite sign When loading lasts just a single construction step there is another way to make loads temporary Rather than applying them with opposite sign in the next step the step can be marked as containing temporary loading only ea Add Temporary Load 1 and Temporary Load 2 as load cases into the first removal step We will reverse their sign later Repeat this process for the second span 36 LARSA 4D Introductory Training Manual for Bridge Projects CT j ox Stage Steps Load Cases Structure Groups Support Activity Slave Master Activity Tendon Activity Disp Init Activity First Segment Self Weight Span 1 S
48. is manual For More Information please refer to the following documentation e For more information on defining tendons see Tendons in LARSA 4D Reference Manual 46 LARSA 4D Introductory Training Manual for Bridge Projects Time Dependent Material Effects LARSA 4D s Time Dependent Staged Construction Analysis is a more advanced version of the Staged Construction Analysis that includes time dependent effects including the effect on concrete elastic modulus creep shrinkage steel relaxation for tendons and the effects of superimposed loads The CEB FIP 78 or CEB FIP 90 codes are supported among several others The user must choose a code so that the analysis knows which rules to follow and which input to ask from the user CEB FIP 78 is the more flexible code and is based on user supplied time property curves for each section whereas CEB FIP 90 is equation based and requires very little input from the user For this example we will use CEB FIP 90 A time dependent analysis has the following steps Choosing the design code Indicate which materials or sections are subject to time dependent material effects and what their time dependent properties are No members undergo time dependent changes unless their material or section is explicitly marked as a member having time dependent effects Setting the casting day on each concrete member that undergoes time dependent effects Creating the appropriate construction stages at
49. k OK and save the file along with your project You may use the file name basic bridge example sections Remember where you save the file You will need to find it in the next section It will have a LPSX file extension For More Information please refer to the following documentation e Properties in LARSA 4D Reference Manual 10 LARSA 4D Introductory Training Manual for Bridge Projects Geometry Because this model is of a straight bridge we will lay out the geometry along the global x axis starting at 0 The pier will be at 100 feet The final abutment will be at 200 feet The elevation axis will be the global z axis There are several ways to enter geometry in LARSA 4D using spreadsheets the Model Data Explorer drawing the geometry graphically with the mouse the generation and transformation tools and importing geometry from other programs such as Excel or CAD software We will start by using the spreadsheets in this tutorial Model geometry in this tutorial consists of three types of objects joints members and grounded springs Joints represent connection points between elements and have six degrees of freedom Members are two node line elements They will be used to represent the girder Grounded springs are one node spring elements used to model soil structure interaction or connections between bridge superstructure and piers or abutments at bearings Joints a Open the geometry spreadsheets using Input Data
50. le ge Set the factors on each as appropriate Then click OK Name 1 2 Right Lane 1 2 Left Lane Right Lane Lefl Available Result Cases Pushover Cases Combo with Moving Load Cases Stage Analysis Scenario s RSA Modal Influence Based Right Lane Left Lane 3 Linear Combinations Right Lane Left Lane Extreme Effect Groups X Help Class None v Cases in Group Result Case Factor Right Lane 1 2 All Left Lane 1 2 All Right Lane Left Lane 1 All Extract Load Class Allow Positive Minimum and Negative Maximum OK Cancel Extreme Effect Group for Right Lane 30 LARSA 4D Introductory Training Manual for Bridge Projects Youll find the new groups in the Analysis Results Explorer in a new section called Extreme Effect Groups You can access the results for these cases like any other case Use the results spreadsheets with these cases to find the controlling effects on each lane For More Information please refer to the following documentation Lanes in LARSA 4D Reference Manual Influence Line amp Surface Analysis in LARSA 4D Reference Manual Influence Coefficients Graphical View in LARSA 4D User s Manual Linear Result Combinations in LARSA 4D User s Manual e Extreme Effect Groups in LARSA 4D User s Manual l LARSA 4D Introductory Training Manual for Bridge Projects 32 LARSA 4D Introductory Training Manual for Br
51. lso change its start position to 0 5 meaning the middle of the member Joint Loads Support Disp Member Loads Plate Loads Moving Loads N Time History Y RSA Loads Basic Loads Thermal Loads Member Magnitude at Start kins or 100 0000 Magnitude Start Position End Position at End from start kips or x L Direction Global Z 0 5000 Point Force Construction Loading First Segment Click the second temporary load case and add the next member load the same but on member 9 And then do the same for the third and fourth cases members 13 and 18 Close the loads spreadsheet The Load Cases Explorer will indicate the type of loading in each case Add Load Case y Add Combo d Load Cases 4 Self Weight Self Weight 1 Z 4 Temporary Load 1 2 Member Loads 1 4 Temporary Load 2 2 Member Loads 1 4 Temporary Load 3 LL Member Loads 1 4 Temporary Load 4 LL Member Loads 1 Construction Loading Verify that the loading is correct in each case in the graphics window Construction Stages Now we are ready to set up the staged construction stages and steps A construction step is a set of construction activities that occur simultaneously This will involve constructing part of the girder as well as applying loading A construction stage consists of all of the construction steps that occur on a particular day of construction Const
52. n LARSA 4D is waiting for you to choose a location on the structure to maximize the forces at Click any member to see influence coefficients for it Be sure the Pointer tool is active You will be prompted to enter a station number for where you would like to see the coefficients The stations range from 0 to the number of stations configured to be drawn graphically as Enter 0 to see the coefficients at the start of the member The graphics window updates to show the influence coefficients and the locations of axles at their worst position Arrows indicate the locations of the axles of the vehicle specified by the active result case that produce the maximum moment at the chosen location You can switch between placing the axles at the maximum and minimum i e most negative locations in the floating Graphical Results Options window af Moment Mz Envelope Max iew Full Cumulative Results J Influence Coefficients View s Turn off graphical results and close any open spreadsheets 29 LARSA 4D Introductory Training Manual for Bridge Projects Combining the Left and Right Lanes In order to compute the effects on the structure for AASHTO LRFD we need to combine the effects of the left and right lane Because of multiple presence factors there are three cases to consider The right lane may be loaded individually with a multiple presenence factor of 1 2 Similarly for the left lane Or the two lanes may be loade
53. ng time dependent effects The days entered into LARSA 4D are all relative We will choose day 10 as the day on which the concrete members are cast i e poured They will be constructed i e added to the model as load bearing elements on day 30 Then because we are interested in the time dependent effects following the final day of construction we will be interested in the state of the structure on various days up to 5 years in the future By default the casting day of members is day 0 We will modify the casting day on the members spreadsheet Open the members spreadsheet Scroll over to the right and change the Casting Day to 10 for all members It will help to use the spreadsheet edit tool in the toolbar to change all cells at once The casting day is ignored for members for which the time effect on elastic modulus does not apply In this model all member elements are concrete and are subject to the time effect on elastic modulus Close the members spreadsheet The next step is to set the day of construction for the construction stage The temperature and humidity on this day is also important Open the Construction Stages spreadsheet from Input Data Construction Stages Change the Construction Day of the stage to day 30 Change the Temperature of the stage to 64 degrees F and the Humidity to 70 percent We want to investigate the state of the structure at several time points later on Each time point to
54. nly The Load Cases Explorer is the primary way to create load cases Click the Load button above the Model Data Explorer to activate the Load Cases Explorer The Load Cases Explorer will take the place of the Model Data Explorer Add a new load case by clicking the Add Load Case button at the top of the explorer Right click the load case and choose Properties Change its name to Self Weight Then enter 1 in the Weight Factor Z field to indicate that gravity applies in the negative z direction with a factor of one The Z button enters this value for you Click OK to finish changing the properties of this load case Add Load Case y Add Combo X E Load Cases Self Weight Self Weight 1 Z 3 Load Combinations Load Case Properties Properties Name Self Weight Type Static Load Class None lata ui ut v Active Cancel Help Self Weight Load Case For More Information please refer to the following documentation Self Weight in LARSA 4D Reference Manual 17 LARSA 4D Introductory Training Manual for Bridge Projects 18 LARSA 4D Introductory Training Manual for Bridge Projects Linear Static Analysis At this point we will run a linear static analysis The analysis will compute the effecs of the self weight load case created in the previous section From the Analysis menu choose Linear Static P Delta Analysi
55. ntered in degrees relative to the member s x axis which is in this case and is normally the centroid 42 LARSA 4D Introductory Training Manual for Bridge Projects Parabolic f Parabolic specified y at both ends X a iz cP 10 Member Side View PI Point CAlculated Tendon ParabolicCurve Fitting We will replace the circular curve with a parabolic curve ee Click the very first geometry control point in member 1 to select it Change its curvature type from Corner to Parabolic ee Enter a Y Angle of 10 degrees ee Click Update ee Click the second geometry control point in member 7 to select it Change its curvature type from Circular Radius to Parabolic ee Enter a Y Angle of 0 degrees ee Click Update We enter a Y Angle of zero for the second control point because the tendon is parallel to the member at this location Notice the updated diagram with the smooth curve ee Set up a similar curvature on the end of the tendon Change the curvature type on the final two geometry control points to Parabolic The Y Angle on the third point should be zero The Y Angle on the final point should be positive 10 Be sure to click Update after changing each point The tendon now appears as in the first figure in this section There is also a spreadsheet for editing tendon geometry In the Model Data Explorer or tendons geometry spreadsheet right click the tendon and choose Path Spreadsheet The tendon path s
56. of a tendon such as A992 Click the material so it is checked Change to the Concrete category and choose a material appropriate for the girder section such as Fc_4 Click the material so it 1s checked Click OK to import the materials Cross Section Properties We will use a parametric cross section shape for the T section which comes in LARSA 4D s custom section shape library Goto Input Data Sections Click the Custom tab a Find the T Beam group expand the group by double clicking it and choose Single T Bridge Beam The shape is customized by setting its name and seven dimension parameters Set the name and parameters according to the figure below 9 LARSA 4D Introductory Training Manual for Bridge Projects Standard Custom Sections Standard Custom in Single T Bridge Beam Monbar 7 AASHTO Tub Girder O NRS m AASHTO Tub Girder Girder T Section Plate Box Girder Cover Top Plate Box Girder Open Top Basic Shapes Columns Box Beams Box Girders T Beam Double T Beam Single T Beam With Plate Single T Bridge Beam T Beam Beam Steel Box Girders B Show dimension lines mle x B al al Importing a custom T shape section Click Import to bring the section definition into the project LARSA 4D will ask whether it is OK to create a new parametric section database for the model in which to put the section definition ee Clic
57. omial ourselves However LARSA 4D has a formula helper tool that makes it easier to construct complex formulas for non prismatic variation Click the f for formula next to the d parameter field The formula helper opens with a window to change the linear variation Rather than typing in a formula from scratch the helper has fields for the start 72 and end values 50 It will create the appropriate formula Change to the Parabolic tab Enter a start value of 72 an initial slope of 88 and a final slope of 88 Click OK The side view preview diagram will update to show the curve The parameters spreadsheet will also show the actual equation in x used You can substitute 0 5 for x to verify that the depth at mid span is 50 inches Note that the initial slope of 88 refers to the fact that depth is decreasing at the start The slop is in depth units inches per units of the x variable which ranges from 0 0 at the start to 1 0 at the end of the span Click Close Verify that the complete rendering diagram in the graphics window shows the haunches properly Piecewise Variation Now we will create the piecewise variation function Return to the Edit Parameters window by going to the sections spreadsheet and then right clicking the section row e Click the f for formula next to the d parameter field Click the Piecewise Function checkbox at the bottom of the window A spreadsheet opens to
58. preadsheet includes all of the same information as in the Tendon Editor Additionally however you must specify every member that the tendon passes through If the tendon passes through a member in which there is no need for a geometry control point the member is added with the point type called path only E TENDON Tendon 1 lol x Tendon Path Geometry Force Distance Graph Force Calculations Reference Point Type Reference Object Object or er Y Ea Z X Reference Y Reference Type Range geometry 1 0 0000 0 0000 0 0000 Start Reference Line path only path only path only path only geometry 0 0000 5 0000 0 0000 Start Y3 Local Edge Re path only Show Only Selected Objec Tendon Path Spreadsheet Setting Tendon Properties me Keep the tendon editor window open but also open the geometry spreadsheets from the Input Data menu and change to the Tendons spreadsheet 43 LARSA 4D Introductory Training Manual for Bridge Projects Rename the tendon to Tendon 1 and set its properties as Material A992 Strand Area 2 in of Strands 3 Jacking Force Start Anchor Set 0 15 in Wobble Coefficient 5500 kips 0 0001 per ft Curvature Friction Coefficient 0 15 Close the tendon geometry spreadsheet The Tendon GUTS property of the steel material for the tendon must be entered e Open Input Data Properties Materials gt More Properties Set the Tendon GUTS guar
59. riation is applied not just over the length of a single member but across multiple members In this example we will create haunches over the abutments and the pier The cross section will decrease in depth from the first abutment over several feet remain constant and then shortly before the pier it will begin to increase in depth again The second span will have the same shape I a se re a en a es ae ae aoa mar Haunches Keep in mind when creating non prismatic variation that member elements are still assumed to have constant properties throughout their length during an analysis Members must be divided into sufficiently short pieces so that any smoothly curved non prismatic variation 1s approximated as close as necessary Creating a Non prismatic Section Before we create the non prismatic variation that we want for this model which involves a complex definition for depth we will start with a simpler case Let us have the depth vary linearly from 72 inches at the abutment to 50 inches at the pier We will modify the existing cross section definition in the project and add this variation Open Input Data Properties and change to the Sections tab Right click the T section and choose Edit Parameters 55 LARSA 4D Introductory Training Manual for Bridge Projects Parametric Section Girder T Section _ Section Diagram Properties Composite Parts External Databases Member Y x Variable R
60. ruction stages are used for time dependent staged construction analysis where the day of construction matters In this example we will place all construction steps in a single construction stage amp Goto Input Data Construction Stage Editor Double click Add New Stage and leave the name as Stage 1 30 LARSA 4D Introductory Training Manual for Bridge Projects Then double click Add New Step to Stage 1 and change its name to First Segment Do the same to create the next construction step for the second segment exe After the first two steps create a third step Remove Temporary Loads 1 Do the same to create the construction steps for the second span the third segment the fourth segment and Remove Temporary Loads 2 ini x Stage Steps Load Cases Structure Groups Support Activity Slave Master Activity Tendon Activity Disp Init Activity Const Deconst Construction Method Fourth Segment Construction Remove Temporary Loads 2 Construction Standard Add New Stage Add New Step to Stage 1 Construction Steps The next step is to apply construction activities The first step will include an activity to assemble the first five member elements e Change to the Load Cases Structure Groups tab ee Click the drop down arrow next to Add Group besides the first construction step and choose Span 1 Segment 1 Self weight is not applied during Staged Construct
61. s There are no options for this analysis type Click Analyze You will be prompted to save the project and to compute the torsion constant for the cross section definition Do so Once the analysis completes successfully close the analysis window The Analysis Results Explorer will be automatically opened on the right side of the scren Set the results units to the Imperial defaults inches for displacement and kips for forces in Results Units e Open the Load Cases group and select the Self Weight result case from the Analysis Results Explorer Select result cases to view from the list below amp Load Cases Self Weight Load Combinations Construction Stages Moving Load Cases Time History Cases Pushover Cases Combo with Moving Load Cases Stage Analysis Scenario s Select the Self Weight Result Case There are several ways to examine analysis results in LARSA 4D including graphics and spreadsheets We will demonstrate graphical results first Turn on Deformed Model graphical results either from the Results menu or the toolbar Results Design Tools Window Help Graphical gt None Spreadsheets Deformed Model Minimum Maximum E be fo Graphs IT Member Stresses 2 Tendon Results 898 Plate Deformations Linear Combination p Piste Fosces Group for Extreme Effect m Plate Stresses A Influence Line Surface Case Animate Result Cases Response Sp
62. s Importing materials and custom parametric sections e Creating joints in the spreadsheets e Drawing members and creating members in the spreadsheets Creating bearings using simple linear grounded springs and 6x6 stiffness matrix definitions Using rigid members Refining the model using Break Members e Creating a self weight load case Viewing the results of a linear static analysis with graphical results and results spreadsheets 5 LARSA 4D Introductory Training Manual for Bridge Projects In the second half of this guide we will cover several analysis techniques Live load analysis for AASHTO LRFD with influence lines e Structure Groups e Staged Construction Analysis e Temporary Loads Support Change Activities e Post Tensioning with tendons e Material time effects under CEB FIP 90 Creating haunches with non prismatic cross section variation About LARSA 4D LARSA 4D is an advanced multipurpose 3D structural analysis package featuring a powerful graphical user interface and an analysis engine with unmatched analytical features including influence line and surface based live load analysis staged construction analysis time dependent material properties and segmental construction analysis hysteretic and seismic elements and seismic analysis and progressive collapse The LARSA structural analysis engine has been in commercial use for over 25 years It was originally developed to perform nonlinear static analysis of stru
63. s P7A Normal Normal Normal Normal Member Station Result Case Centroid Stress Stress Stress Stress kipsin Point 1 Point 2 Point 3 Point 4 1 1 0 Load Cases 0 0346 0 0581 0 0581 0 2908 0 2908 2 1 1 Load Cases 0 0346 0 0092 0 0092 0 1558 0 1558 3 1 2 Load Cases 0 0346 0 0371 0 0371 0 0278 0 0278 4 1 3 Load Cases 0 0346 0 0810 0 0810 0 0933 0 0933 5 1 4 Load Cases 0 0346 0 1223 0 1223 0 2073 0 2073 6 1 5 Load Cases 0 0346 0 1610 0 1610 0 3144 0 3144 li 2 0 Load Cases 0 0346 0 7136 0 7136 2 1013 2 1013 8 2 1 Load Cases 0 0346 0 6385 0 6385 1 8938 1 8938 z 2 2 Load Cases 0 0346 0 5659 0 5659 1 6934 1 6934 10 2 3 Load Cases 0 0346 0 4959 0 4959 1 4999 1 4999 Member Stresses Close the spreadsheet window before going on For More Information please refer to the following documentation Linear Static Analysis in LARSA 4D Reference Manual e Analysis Results Explorer in LARSA 4D User s Manual e Viewing Results Graphically in LARSA 4D User s Manual 20 LARSA 4D Introductory Training Manual for Bridge Projects e Results Spreadsheets in LARSA 4D User s Manual 21 LARSA 4D Introductory Training Manual for Bridge Projects 22 LARSA 4D Introductory Training Manual for Bridge Projects Influence Line Live Load Analysis Influence line and surface analysis is an extension of the moving load analysis which uses the effects of a unit load to rapidly compute t
64. secondary moments at this point in time You must select a result case with post tensioning PT activity to get long term tendon results Tendon Editor e coe x Tendon Geometry Forces amp Losses Primary amp Secondary Moments Tendon 1 Forces Along Tendon Tendon 1 Eben i ee 160 00 180 00 200 00 0 00 20 00 40 00 60 00 80 00 100 00 120 00 140 00 Arc Distance Along Tendon ft Force kips Short Term Losses After Anchor Set Force at Jacking Long Term Losses Five Years Other PT Losses Elongation 1st Pull 6 106300449 Left n a 2nd Pull n a Right n a Long Term Tendon Losses 53 LARSA 4D Introductory Training Manual for Bridge Projects 54 LARSA 4D Introductory Training Manual for Bridge Projects Haunches Haunches are added to the model using non prismatic variation of cross section geometry and properties Non prismatic variation can be added to any parametrically defined cross section definition including the custom section shapes and sections defined in LARSA Section Composer Non prismatic variation is created in two steps First formulas must be assigned to parameters in the cross section to determine how the parameters vary over the length of the span These formulas can define arbitrary curves including linear variation parabolas and cubic curves The second step is to apply the cross section to the model possibly using special span definitions so that the va
65. t curves reaching 5 inches above the bottom of the web at the mid span of the two spans the start of members 7 and 16 and comes back up to the centroid at the end Tendons can take any path through 3D space Geometry control points determine the path of a tendon These control points are placed inside of members Hold the key and click inside of member 7 Then do the same inside member 16 This creates control points inside the two members We will set their locations next ee Click the first new control point the one inside member 7 s In the lower right panel change the X offset to zero meaning the start of the member B Set the Y offset field to 5 and then change the reference from Axis meaning the member reference axis here the centroid to Y3 Y3 signifies that the reference coordinate in the member is the third stress recovery point set in the cross section definition By convention the third stress recovery point is at the bottom of the section as 1t is 1n this case ee Click Update 41 LARSA 4D Introductory Training Manual for Bridge Projects Do the same for the second new control point O x _f Tendon Editor Tendon Geometry Forces amp Losses Primary amp Secondary Moments TENDON lt New Tendon gt Selected CTAL click to add a new geometry point in a member Y Axis Z Axis IV Shrink Tendons New Tandon r the Geometry Point Tendons Check Geometry Member j
66. the right where we can configure a complex piecewise function 58 LARSA 4D Introductory Training Manual for Bridge Projects In the first row in the piecewise definition spreadsheet enter 0 0 for start x and 0 2 as end x We are treating the x variable as ranging from 0 0 at the start of the span to 1 0 at the end This condition refers to the first 20 of the span or 20 feet se Change to the Haunch tab Enter a start value of 72 and an end value of 50 In the last blank row in the piecewise definition spreadsheet enter 0 2 for start x and 0 8 as end X In the Custom Equation field just enter 50 In the last blank row in the piecewise definition spreadsheet enter 0 8 for start x and 1 0 as end X Change to the Haunch tab Enter a start value of 50 and an end value of 72 Change the Left Side option to Right Side CA Parametric Equation Editor Custom Equation Linear Haunch Parabolic Sinusoidal Piecewise Definition Start Value End Yalue 50 72 Right Side M Piecewise Function Cancel Creating piecewise variation in depth e Click OK The side view preview diagram will update to show the haunches e Click Close Verify that the complete rendering diagram in the graphics window shows the haunches properly e Re run the analysis with the new cross section properties and inspect the results For More Information pl
67. truction Stage Cancel Day 1800 Five Years v Keep Previous Results V Perform Quick Integrity Check Description Performs a standard construction analysis but includes time dependent material effects Staged Construction Analysis Options ee Click Analyze Close the analysis window when it finishes without errors 50 LARSA 4D Introductory Training Manual for Bridge Projects Results In a Time Dependent Staged Construction Analysis new result cases are automatically generated in each stage for the effects of creep shrinkage relaxation and other losses Analysis Results Select result cases to view from the list below S Construction Stages S Stage 1 Stage 1 First Segment Stage 1 Second Segment Stage 1 Remove Temporary Stage 1 Third Segment Stage 1 Fourth Segment Stage 1 Remove Temporary Stage 1 step a 75 Days 75 Days Creep 75 Days Shrinkage 5 Days PT Relaxation 75 Days Other PT Losses 200 Days S Two Years Two Years Creep Two Years Shrinkage Two Years PT Relaxation Two Years Other PT Losses a Five Years Five Years Creep Five Years Shrinkage Five Years PT Relaxation Five Years Other PT Losses Time Dependent Result Cases Step through deformed model graphical diagrams at a scale factor of 256 from the first result case to the last to see the effects of the time dependent material properties ex If not all of the
68. ty Disp Init Activity Stage 1 X Free Remove Temporar Add Activity Temporary Support Activities Click Close when done Look back in the Construction Stages Explorer to verify that the input is correct Oo LARSA 4D Introductory Training Manual for Bridge Projects Construction Stages Gj AddStage p AddStep X 4 View 3truc Load Activ ENDO E Stage 1 day 1 EHI First Segment Span 1 Segment 1 Self Weight f 1 00 k Temporary Loads 1 f 1 00 Joint 10 Tz Fixed Tsy Axyz Free Second Segment A Span 1 Segment 2 Self Weight f 1 00 4 Temporary Loads 2 f 1 00 Joint 10 All DOF Free HI I Remove Temporary Loads 1 4 Temporary Loads 1 f 1 00 E 4 Temporary Loads 2 f 1 00 TT Third Segment I Span 2 Segment 1 Self Weight f 1 00 E 4 Temporary Loads 3 f 1 00 Joint 19 Tz Fixed Txy Rxyz Free I Fourth Segment Span 2 Segment 2 Self Weight f 1 00 Temporary Loads 4 f 1 00 Joint 19 All DOF Free HI Remove Temporary Loads 2 4 Temporary Loads 3 f 1 00 4 Temporary Loads 4 f 1 00 Construction Stage Loading Notice the f 1 00 next to each load case This is a load factor We will change these load factors to 1 to remove the temporary loading ee Click Temporary Loads 1 in the Remove Temporary Loads 1 step At the bottom of
69. used for CEB FIP 78 only so we will not need to enter them Material Time Effect definitions may also be assigned to section definitions in the project 1f it is more convenient but a member should not have a Material Time Effect definition on both its material and section Goto Input Data Properties and change to the Material Time Effects tab Add one row to the spreadsheet and change the name of the material time effect definition to Concrete Time The CEB FIP 90 code provides curves for concrete creep shrinkage and the time effect on elastic modulus It is possible to override the built in curves through the CEB FIP 90 menu that shows up when viewing this spreadsheet but we will not do that here If CEB FIP 78 is used or if any of the property overrides are specified you may need to have separate Material Time Effect definitions for each material in the project But if the materials share the same time effect settnigs you can use the same Material Time Effect definition for multiple materials We will need to verify the default curves for stress GUTS versus relaxation and time versus relaxation for tendons Add a second row to the spreadsheet and change the name to Steel Time WF Properties CEB FIP 90 ooe Materials Sections UCS Spring Properties Isolator Definitions Material Time Effects Name Creep Factor Shrinkage Factor Relaxation Factor Steel Relaxation Type Assigned 1 Concret
70. using a span break marker Each row in the path spreadsheet is a geometry control point in 3D space The row for member 2 creates a geometry control point at the start of member 2 which is at the pier A span break marker in the next row indicates the previous geometry control point ends a span Insert a row into the spreadsheet after the row for member 2 and change its point type to span mark 24 LARSA 4D Introductory Training Manual for Bridge Projects Lane Surface Path Geometry Pant ae Reference Object feng Offset Y Offset Z yP Type Ren a in in member 11 0 0000 0 0000 72 0000 member 2 0 0000 0 0000 72 0000 geometry member 12 0 0000 0 0000 72 0000 geometry member 13 0 0000 0 0000 72 0000 Lane Span Break Marker Close the lane spreadsheet The lane graphics window will also automatically close This is the right lane To create the left lane we can duplicate the first lane definition and then shift it 12 feet to the left Right click the lane in the Model Data Explorer and choose Duplicate Lane Rename the new lane Left Lane Right click the lane in the explorer and choose Edit Path amp View Change the Offset Z to 72 for all rows Then close the lane spreadsheet A Right and Left Lanes Preparing the Influence Coefficients The Load Case The load case setup specifies additional options for how the lane is loaded including the grid spacing of influence coefficients

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