STA PILE 3 INSTRUCTION MANUAL
Contents
1. JH STA PILE3 USER MANUAL Version 1 8 December 2009 STA PILE3 ANCHOR PILE DESIGN USING API RP 2A WITH SUCTION EMBEDMENT OPTION Version 1 8 December 2009 USER MANUAL STA PILES is a computer program for the design and analysis of pile anchors The piles are treated as being short with a free head condition The attachment point or padeye for the mooring line may be at any point on the pile The pile may be driven into the sea bed or may be embedded by suction The pile may be fully embedded partially embedded or may be driven deep beneath the sea bed STA PILES permits the user to soil layers each of which may have The layers may be a mixture of soils Primary results from the capacity of pile anchrs for vertical Additionally the program provides failure and provides an ultimate vertical and horizontal loading The calculate suction embedment conditions The differential pressure requred to embed a suction anchor is calculated and a warning is given if the plug inside the anchor will lift For cylindrical steel piles maximum axial and bending stresses in the pile are also calculated specify up to three different varying strength properties cohesive and _ cohesionless program provide the ultimate and horizontal loading factors of safety against capacity check for combined program may also be used to This program has been developed by Stewart Technology Associates STA All copyright for the software and document2. The STA PILE3 icon is shown to the right STA PILE3 USER MANUAL Version 1 8 December 2009 JV STEWART TECHNOLOGY ASSOCIATES JH WwwWww stewart usa com USA and Caribbean v 1 7 March 2004 Run ref Corocoro PLEM piles 5 3 2006 15 48 Copyright Stewart Technology Associates 1992 and onwards For support telephone 713 789 8341 or fax 713 789 0314 Explain value Select Analysis Type and Apply Loads Assumptions Friction Print Input amp Results Navy soil design parameters API Cohesionless soil design parameters For pile top below sea bed make ztop negative SOIL PROPERTIES up to three layers PILE PROPERTIES and ANALYSIS OPTIONS Z1 thickness of upper soil layer ft soil pile Fy Yield stress for pile steel ksi pile mass density Ib cuft Z2 thickness of middle soil layer ft friction Lp length ft no radial bulkheads Z3 thickness of lowest soil layer ft angles ztop top to seabed ve if buried ft radial bulhead thickness in Phi1 1st layer friction angle deg 0 zc dist pile head to pad eye ft pile top thickness in Phi2 2nd layer friction angle deg 0 pile OD in cu reduction factor Phi3 3rd layer friction angle deg 25 t pile wall thickness inches 2 Installed capacity analysis cu1 undrained sh strength top 1st layer psf E Young s
3. Ibf in 2 0 00 multiplier on base shear 1 full O none 20 7 13 43 T rel stiffness avg value 4 79E 03 for pile in in 4 30 2 61 L T embed length stiff factor T 243 average skin friction psf 40 17 50 L B embedment length pile OD 9 21 fb max bending stress in pile in ksi from Hult llllli tite ieee layer 1 2 max ve BM from Hult ft kip 0 74 fa max axial stress in pile in ksi from Vult BO See er a ea eee layer 2 306 max ve BM from Hult ft kip 9 95 max combined stress in pile in ksi from ult loads 60 I He i Me padeye shown and depth in feet Explain Select Analysis Type and or Change Applied Loads J a pear Horizontal Shear Force Horizontal Soil Reactions kip feet Kips kip ft 350 50 40 20 0 20 40 60 8 6 4 2 0 2 4 6 0 0 0 100 100 100 200 200 200 3 300 E300 300 amp 400 9400 T 400 a Q al 500 500 ale 500 600 SS E S E 600 u p 600 700 l i 700 700 FIGURE 2 User Area of Main Worksheet www stewart uSa cOM USA and Caribbean Version 1 8 December 2009 5 0 RUNNING THE PROGRAM Once you have set up the program using the instructions in Section 4 0 you will be able to click on the STAPILE3 icon to start Excel and STA PILES The main spreadsheet STAPILE3 XLS will load If you can see the button labeled Select Analysis Type and Apply Loads simply click once on this button You may need to m
4. These loads will be retained in this dialog box and loaded into the worksheet each time you select the nstalled Pile Capacity Analysis option If you select to perform a suction embedment analysis these loads will still be retained in the dialog box but the horizontal applied load will be set to zero on the worksheet and the load necessary to Cause suction embedment will be calculated as the vertical applied load An example of how this dialog box looks is shown in Figure 4 JV STEWART TECHNOLOGY ASSOCIATES JH GTA PILES USER MANUAL wwWww stewart usa com USA and Caribbean Version 1 8 December 2009 STA PILES A PROGRAM FOR THE DESIGN AND ANALYSIS OF PILE ANCHORS Select the Form of analysis to be performed by clicking one of the option buttons below cane Installed pile capacity analysis C Suction Embedment Analysis Define loads to be applied in input boxes below 251 3 Horizontal Applied Load kips 198 5 Vertical Applied Load kips positive load is applied upwards Loads will only be used if installed capacity analysis is selected FIGURE 4 Once you have set the analysis type you may edit any of the cells in the input data section of the worksheet A full description of the meaning of all the terms in this section of the worksheet is contained in Appendix A Please note that the program uses iterative calculations to determine whether or not the pile is plugged if an open ended pile analysis
5. the soil strength and weight parameters at the bottom of the third layer will be continued downwards Gammat 1st layer buoyant weight pcf This is the submerged or buoyant weight of the soil in the first layer Units are in pounds per cubic foot Gammaz2 2nd layer buoyant weight pcf This is the submerged or buoyant weight of the soil in the second layer Units are in pounds per cubic foot Gamma3 3rd layer buoyant weight pcf This is the submerged or buoyant weight of the soil in the third layer Units are in pounds per cubic foot Fy Yield stress for pile steel ksi This is the yield stress for the pile material This term is used in calculating a unity stress check for the pile considering the combined effects of axial and bending stresses ztop top to seabed ve if buried ft This is the distance of the pile top to the sea bed Units are in feet If the pile top is at the sea bed this term will be zero If the top of the pile is above the sea bed this term will be a positive value If the pile top is driven beneath the sea bed this term will be negative zc dist pile head to pad eye ft This is the distance in feet from the top of the pile to the pad eye If the pad eye is at the top of the pile this term will be zero pile OD in This is the outside diameter of the pile specified in units of inches Page 23 www stewart uSa cOM USA and Caribbean Version 1 8 December 2009 t pile wall thic
6. Modulus pile psi 1 closed end 2 open cu2 undrained sh strength bottom st layer psf 35 Hmax applied lateral load kip cu switch 1 psi 2 old API method cu3 undrained sh strength top 2nd layer psf 17 Vmax applied vert load ve up kip 1 underconsol 2 normal cu4 undrained sh strength bottom 2nd layer psf cu5 undrained sh strength top 3rd layer psf 1 01 Horizontal load safety factor Explain value cu6 undrained sh strength bottom 3rd layer psf 3 14 Vertical load safety factor Gamma1 st layer buoyant weight pcf 0 40 Unity stress check app loads Gamma2 2nd layer buoyant weight pcf 1 61 Ult capacity unity check Meyerhof Gamma3 3rd layer buoyant weight pcf open Short pile criteria probably OK 53 Vult ult vert capacity in kips n a n a Pile Elevation 332 f dist top to rotation center in n a plug resistance kips 9 09 ifb max bend str from Hmax ksi 0 00 weight radial bulkheads kips ail isad 0 24 fa max ax str from Vmax ksi 0 00 weight of pile top kips 0 9 33 fmax comb str applied loads ksi 7 48 pile weight in water kip m 8 61 pile weight in air kips 64 00 editable density of sea water Ib cuft 1 39E 11 El for pile
7. OF INPUT DATA aacccequnescraravocanaccnacavasanecararareaneresaserennecasurazasccoancaan 21 Z1 thickness of upper soil layer ft ccc ceecceececeeeseeeecececeeeceeeeaeeseeeseeseneeeseeeseatens 22 Z2 thickness of middle soil layer ft cccccccsececececeeeeeeeeceeeseeeeeeeeseeseeeeseeeseeeeaeeeas 22 Z3 thickness of lowest soil layer ft cccccecceecceeeceeeceeceeeceeeseeeceeeueceeeseeesaeeseeeees 22 Phi1 1st layer friction angle deg ccccecccseeccceeeeceeeeeeeeeseeeeseueeseeeseeeeseeesseeeseesenees 22 Phi2 2nd layer friction angle AEG ccsccccseecceeeeeceeeeneeeeseeeeseeeeseueeseeesaeeeseeeeseeeesees 22 Pie ard layer NCION angle 1EG sessir e EE E REEERE 22 cul undrained sh strength top 1st layer OSf ccccceececseeeeeeeeeeeeeeeeeeeeeeesseeesaeeeeas 22 cu2 undrained sh strength bottom 1st layer Sf cceceecsseeeeeeeseeeseeeeneeeeeeeeeeeens 22 cu3 undrained sh strength top 2nd layer psf cceccseceseeeceeeeeeeeceeeeeeeeseeeseeeseeeens 22 cu4 undrained sh strength bottom 2nd layer DSf ccecceeseeeeeeeceeeseeeeneeeeeeeeeeeens 23 www stewart uSa cOM USA and Caribbean Version 1 8 December 2009 cud undrained sh strength top 3rd layer PSP ccceccsececeeeceeeeneeeseeeeeeeneeeseeeseeeens 23 cu6 undrained sh strength bottom 3rd layer psf cceceecseeeeseeeseeeseeeeneeeseeeeaeeens 23 Gammat1 1st layer buoyant we
8. is performed As soon as you have selected the analysis type the worksheet environment will be set within Excel to perform iterative calculations While the iterative scheme is relatively robust you may find that you can specify inappropriate input data which will cause the system to fail The failure will be manifested by error messages occurring in Results cells You should normally be able to rectify this situation by correcting your input data However it may be necessary to switch from a suction embedment analysis to an installed pile analysis and specify the pile to be closed ended Once you have corrected your problems of inappropriate data input the program should run successfully JV STEWART TECHNOLOGY ASSOCIATES JH STA PILES USER MANUAL www stewart usa com USA and Caribbean Version 1 8 December 2009 6 0 GETTING HELP In Figure 3 two of the buttons are labeled Explain Highlight any data entry or results cell by clicking on it once and then click once on any Explain button A dialog box will be flashed up onto the screen containing information regarding the selected cell An example of this is shown in Figure 5 In this figure the user has selected the input cell cu switch A dialog box has been brought up onto the screen describing what this input data selection switch does This term is selection switch which determines iF the skin Friction is to be calculated by the API RP 24 nineteenth edition psi metho
9. that the short pile criteria may be exceeded This is a non fatal warning and the program will still continue 7 2 Vertical Loads Skin friction along the pile is calculated in each of the soil layers API methods Reference 1 are used The shaft in cohesive soil layers the shaft friction f is calculated by the equation 6 4 2 1 from Reference 1 f ac Where a is a dimensionless factor and c is the undrained shear strength of the soil at the point in question The factor a is computed by equation 6 4 2 2 from Reference 1 a 0 5w gt for w lt 1 0 a 0 5w for w gt 1 0 Both of the above equations have the contraint that a may not exceed 1 0 The variable w is equal to c p for the point in question where po IS the effective overburden pressure at the point in question The alternative method for determining pile vertical ultimate capacity described in the commentary to Reference 3 may also be used If this method is desired the user should set the input variable Cswitch to 1 and the shaft friction in cohesive soils will be calculated as follows For C to be less than or equal to 1 4 ton ft F C For C in excess of 1 4 ton ft but less than or equal to 3 4 ton per square foot the ratio of F to C decreases linearlly from unity at C 1 4 ton ft to 1 2 at C 3 4 ton ft For C in excess of 3 4 ton ft F is taken as 1 2 of C Shaft friction in cohesionless soils is calculated by the method described in Reference 3 The
10. 8 0 38 Vmax applied vert load ve up kip Vertical oad safety factor short pile criteria probably exceeded 1445 average skin friction psf JH STA PILE3 USER MANUAL Version 1 8 December 2009 7 3 Ultimate Resistance To Horizontal Loading The method of Brinch Hansen is used to calculate the ultimate lateral resistance of the pile inasmuch as the pile is divided into around 50 elemental lengths This number varies depending upon whether the pile is completely buried or has any of its length above the soil Each elemental length is treated as a rigid unit The maximum passive resistance for each rigid unit however is not found using Brinch Hansen s coefficients but is found using API coefficients Reference 1 This section of the manual reproduces equations from API RP 2A using the same equation numbers as in that document Reference 1 Cohesive Soils The ultimate lateral bearing capacity pu of clay is varied between 8c and 12c except at shallow depths where failure occurs in a different mode due to minimum overburden pressure Cyclic loads caused deterioation of lateral bearing capacity below that for static loads In stiff clays c gt 2000 psf more rapid deterioation under cyclic loading is expected according to Reference 1 The following equations taken from Reference 1 are implemented within STA PILES Pu Increases from 3c to 9c as X increases from 0 to X according to OF SE ET DE 6 7 2 1 and ET
11. G OPEN 6 7 2 2 where Pu ultimate resistance psi c undrained shear strength for undisturbed clay soil samples psi D pile diameter in y effective unit weight of soil Ib in3 J A value of 5 is appropriate for Gulf of Mexico clays and is used in STA PILE3 although this can be user controlled if desired depth below soil surface in X I Xa yD J Cohesionless Soils The ultimate lateral bearing capacity for sand has been found to vary from a value at shallow depths determined by Eq 6 7 6 1 to a value at deep depths determined by Eq 6 7 6 2 At a given depth the equation giving the smallest value of pu should be used as the ultimate bearing capacity Dig Cao Doyo H voecccccescesssessessesstsstsstsessseesesseen 6 7 6 2 where pj ultimate resistance force unit length lbs in s shallow d deep y effective soil weight Ib in gt H depth in angle of internal friction of sand deg C C C Coefficients determied from figure 6 7 6 1 as function of 9 D average pile diameter from surface to depth in In STA PILES coefficients C C2 and C3 are determined based upon the user input angle of internal friction for the soil and by polynomial curve fits to Figure 6 7 6 1 in Reference 1 Note All units for user input terms in STA PILE3 are converted to appropriate values for use in the equations described in this section It is important that the user inputs values in the units shown in th
12. PROGRAM for any purpose at any time The use of the PROGRAM is not limited to a single machine and the USER may make copies of PROGRAM and run it on several machines simultaneously The USER agrees to make any reasonable effort to assure that the PROGRAM file or disk is not copied without authorization by OWNER and that all users in USER s organization are familiar with these Limitations of Use The USER agrees not to modify copy sell lease rent give free of charge or otherwise distribute or alter the PROGRAM or any part thereof to any individual government agency or organization outside of the USER organization COPYRIGHTS All copyrights to the PROGRAM are reserved by OWNER All versions of the PROGRAM are copyrighted by OWNER worldwide beginning with 1991 The following is a trademark of OWNER STA PILES The USER shall clearly and distinctly indicate the copyright in all published and public references to the PROGRAM WARRANTY While the OWNER has carefully developed the software and the software has been tested for accuracy and proper functioning nevertheless the OWNER cannot guarantee its accuracy and correctness If the software fails to perform correctly as a result of errors or omissions by the OWNER or its staff the OWNER will at its discretion rectify those errors and omissions free of all charges to the USER This shall be the limit of the OWNER s liability in this respect OWNER warrants that it has the right to grant thi
13. al Engineering Reference 2 For cohesionless soils nh Is obtained from Figure 5 3 2 in Reference 2 The program contains polynomial expressions which have been fitted to the four curves in this figure each of which is for a different soil relative density Dr The relative density of the soil is estimated by the program based upon the friction angle of the soil specified for a particular layer by the user The following selection criteria are used If u lt 5 Dy 35 If u lt 20 Dr 50 If u lt 30 Dr 65 If u lt 45 Dr 85 If u gt 459 Dy 85 For cohesive soils nh is taken from Figure 5 3 3 in Reference 2 Polynomials are fitted to the two curves in that figure The curve for soft clay is used if the average undrained shear strength for the clay is 1000 psf or less The curve for stiff clay is used if the average undrained shear strength of the clay layer is greater than 1000 psf For each soil layer the value of Dy is computed and a value for the pile soil relative Stiffness T is computed by the equation Page 13 JH STA PILE3 USER MANUAL Version 1 8 December 2009 T EI N A weighted average for T is then computed for the embedded length of the pile based upon the individual values for T for each of the soil layers in which the pile is embedded The value of pile length divided by soil stiffness is reported L T If this value exceeds 3 5 a warning is given by the program to the user
14. ally ncrease wth arength tests on high qualty samples model teats or ple Increasing sand fradionsand decease wth creasing at dtig performanee 15 avalable other wlues maybe uated fractions FIGURE 10 Page 12 www stewart uSa cOM USA and Caribbean Version 1 8 December 2009 7 0 BASIC ANALYSIS ASSUMPTIONS The user can be reminded of the basic analysis assumptions when running the program by clicking once on the button assumptions lf a vertically downwards load is applied to the pile the end bearing resistance of the pile will be calculated 7 1 Stiffness Factors Although the program assumes that the pile behaves as a short rigid unit a stiffness check is performed and a warning is issued if the pile appears to be too flexible compared to the soil stiffness for the case being analyzed The program calculates an average stiffness factor for the pile based upon the stiffness of the pile El value and the compressibility of the soil The soil compressibility is expressed in terms of a soil modulus which is not constant for any soil type but depends upon the width of the pile and the depth of the particular loaded area of soil being considered The soil stiffness is found by the program in terms of the coefficient of subgrade reaction nh The coefficient Np is determined for a user selected value of the ratio Ymax divided by D the pile diameter The method used is that contained in the Navy Handbook For Marine Geotechnic
15. any input data cell and clicking on the button EXPLAIN VALUE the User is presented with a dialog box containing a detailed description of the input data term This Appendix provides a reference for each of these terms Page 21 www stewart uSa cOM USA and Caribbean Version 1 8 December 2009 Z1 thickness of upper soil layer ft This is the thickness of the first soil layer from the sea bed downwards Units are feet Z2 thickness of middle soil layer ft This is the thickness of the second soil layer beneath the sea bed Units are feet Note that a visual check on the input data is provided in the upper diagram on the main results page for the program entitled Pile Elevation Z3 thickness of lowest soil layer ft This is the thickness of the lowest soil layer in the analysis Units are feet Note that if the bottom of the pile is defined as extending to a depth within the sea bed beneath the bottom of this lowest soil layer the properties for the soil at the bottom of the layer will be extended to the bottom of the pile The program will issue a warning if the pile extends below the bottom of the third layer specified by the User Phi1 1st layer friction angle deg This is the friction angle to be used in the analysis for cohesionless soil in the first layer Unis are degrees If the first soil layer is cohesive Phi1 should be specified as zero The program will issue a warning if both cohesive and cohesionless propertie
16. ation remains with STA Users of the program are cautioned to exercise experienced and careful engineering judgment when interpreting the results from STA PILES This is especially important with this program since results can be obtained in seconds on a modern PC This rapid speed and ease of use does not alter the care and attention needed from the user associated with selecting the appropriate geotechnical and loading conditions The program runs in the environment of Microsoft Windows and Microsoft Excel A mouse is used to click on option buttoms in order to move rapidly through the analysis A large number of Help screens are provided No experience of Excel is required to use STA PILES No part of this document should be taken in isolation or out of context and interpreted in a manner inconsistant with the overall framework and intent of this document STEWART TECHNOLOGY ASSOCIATES 728 Bering Drive Unit M Houston Texas 77057 Tel 713 789 8341 Fax 713 583 2058 e mail info stewart usa com Last Revised December 9 2009 www stewart uSa cOM USA and Caribbean Version 1 8 December 2009 EXTRACTS FROM LICENSE AGREEMENT LIMITATION OF USE This License is granted to the USER for an indefinite period The USER agrees that no individual outside consultant government organization or any person who is not on permanent staff with the USER or under direct in house control of USER shall have access to the PROGRAM or shall use the
17. aximize the spreadsheet Do this by clicking once on the negative sign in the upper left hand corner of the spreadsheet From the drop down menu that will appear click once on Maximize Your start up screen should then appear as shown in Figure 3 v 1 7 March 2004 Run ref Corocoro PLEM piles 5 3 2006 15 48 Copyright Stewart Technology Associates 1992 and onwards For support telephone 713 789 8341 or fax 713 789 0314 Explain value Select Analysis Type and Apply Loads Assumptions Friction Print Input amp Results Navy soil design parameters API Cohesionless soil design parameters For pile top below sea bed make ztop negative SOIL PROPERTIES up to three layers PILE PROPERTIES and ANALYSIS OPTIONS Z1 thickness of upper soil layer ft soil pile Fy Yield stress for pile steel ksi pile mass density Ib cuft Z2 thickness of middle soil layer ft friction Lp length ft no radial bulkheads Z3 thickness of lowest soil layer ft angles ztop top to seabed ve if buried ft radial bulhead thickness in Phi1 1st layer friction angle deg 0 zc dist pile head to pad eye ft pile top thickness in Phi2 2nd layer friction angle deg 0 pile OD in cu reduction factor Phi3 3rd layer friction angle deg 25 t pile wall thickness inches 2 Installed capacity analys
18. d or if the old APT method described in the commentary should be used In the psi method In the old AFI method Friction F alpha x Cu f Cu for Cu lt 0 25 ton safti alpha O 5xpsi 5 for psi lt 1 0 F O 5xCu For Cu gt 0 75 tonlsgft alpha 0 5 x psi 25 For psi gt 1 0 A linear variation of F with Cu is used between l the above values of Cu psi Cup p effective overburden pressure at point in question It is simple to investigate the difference between results obtained by either method simply by changing this particular term FIGURE 5 Help is also available in interpreting the results The main summary results for an installed pile analysis are seen in the lower right hand corner of Figure 2 In Figure 6 an enlarged view of a section of Figure 2 it is seen that the ultimate capacity unity check results cell has been selected The dialog box that appears when the Explain button is clicked is shown Figure 7 and explains the basis of this result 257 Hira applied lateral load kip 1 cu suiich J p amp i 2 old API method EE EEE LEE AE EEE 199 IMAX applied vert load e up kip 2 H underconsol 2 nommal 24 35 Horizontal load safety factor Explain value 248 Vertical load safety factor 0 24 Unity stress check app loads O25 108 capacity unity check Meyerhof JV STEWART TECHNOLOGY ASSOCIATES JV GTA PILES USER MANUAL WwwWww stewart usa com USA and Caribbean Version 1 8 Dece
19. design and analysis of piles with a free head condition The program determines the ultimate capacity of the pile in response to a combination of vertical and horizontal loading Being an ultimate capacity approach the program does not consider deflection limitations Those who wish to determine piles suited to conditions which must have limited deflections should use another approach STA has programs for this and inquiries are welcomed The general approach in STA PILE 3 is that of the API Reference 1 The user may define up to three soil layers which may be either cohesive or cohesionless or with combined properties The basic version of the program is set up to handle cylindrical steel piles and the user must specify the pile properties These properties are yield stress pile length pile diameter pile wall thickness and Young s modulus for the steel In addition to analyzing the capacity of installed piles STA PILE 3 may be used to calculate the conditions associated with the installation of suction embedded piles suction embedded piles are installed by causing a differential pressure between the inside of the pile and the surrounding water This differential pressure causes a net downwards force on the top of the pile Under certain conditions the pile will force itself into the sea bed www stewart uSa cOM USA and Caribbean Version 1 8 December 2009 2 0 FAILURE MECHANISM The general failure mechanism assumed by the prog
20. e as shown below Vertical uplift capacity for embedment resistance is calculated Suction embedment may be specified in which case the program computes necessary suction pressure differential Piles must satisfy the criteria For short stift piles FIGURE 1 JH STA PILE3 USER MANUAL Version 1 8 December 2009 3 0 SPECIAL CONDITIONS AT PILE ANCHORS STA PILE3 is designed to take account of the special conditions associated with the design and analysis of pile anchors Several important differences between pile anchors and free standing piles are noted here First the pile anchor is frequently buried beneath the sea bed Second the load applied to the pile anchor is generally from a mooring chain attached to the pile anchor by a pad eye The pad eye may be some distance below the top of the pile anchor Consequently the pile anchor induces passive soil resistance above the point of load application as well as below the point of load application The program accounts for the improved lateral resistance of fully buried pile anchors when the pad eye is at some distance beneath the top of the pile anchor Unlike foundation piles for many offshore structures that are generally long and slender anchor piles are generally stocky with comparatively slenderness ratios API Reference 1 and other design guidance documents authorities generally recognise that the horizontal resistance of a long slender offshore structure foundation pil
21. e input data section of the program Layered Soils Up to three soil layers which may be mixed cohesive and cohesionless layers can be specified by the user in STA PILES In each layer the above equations are implemented for each elemental length of the pile Overburden pressure is calculated for buried cohesionless layers Rotational Failure Calculations In order to calculate the failure mode of a pile anchor subject to horizontal loading the unit passive resistance of each element of the pile at a depth Z below the ground surface is given by the equation Ps PozKaz F CKez Where Poz is the effective overburden pressure at depth z c is the cohesion of the soil at depth z and Kaz and Kez are the passive pressure coefficients for the frictional and cohesive components respectively at depth z For each successive soil layer the depth z is assumed to begin at the top of the soil layer in order to determine the appropriate coefficient Kg or Ke However the effective overburden pressure is calculated from the top of the soil down to the depth of the layer in question Page 17 www stewart uSa cOM USA and Caribbean Version 1 8 December 2009 The total passive resistance on each horizontal element dH is given by the equation dH pzdHB The point of rotation of the pile is then found such that the summation of the passive soil resistance forces times their lever arms above the point of rotation balances the sum of the el
22. e largely comes from the upper sea bed soils The pull out resistance and the resistance to further embedment largely comes from the soil around the lower half of the pile Hence the two types of ultimate capacity can be treated virtually independently In short stocky anchor piles this is inappropriate and combined failures are to be considered rotation caused by horizontal loads and pull out caused by vertical loads JV STEWART TECHNOLOGY ASSOCIATES JH GTA PILES USER MANUAL Wwww stewart usa com USA and Caribbean Version 1 8 December 2009 40 PROGRAM INSTALLATION 4 1 Introduction STA PILES is a computer program for the design and analysis of pile anchors The latest release of the program Version 1 9 December 2009 runs in the environment of Microsoft Excel 2007 under Windows XP Vista or Windows 7 The program is distributed as an Excel workbook with macros and some Visual Basic code 4 2 Install Files and Create Directories STA PILES must be set up in sub directory on your hard disk Before installing STA PILE3 you must have Excel already installed on your hard disk You must manually set up the necessary directory and copy the files over 4 3 Install Icon Once the directory structure has been created and the program files have been copied from the distribution floppy diskette to the STAPILE sub directory you can set up the icon see your Windows documantation or simply right click on your desktop and be intuitive
23. ement passive resistances multiplied by their lever arms below the point of rotation Having found the depth to the center of rotation from the above approach the ultimate lateral resistance of the pile to a horizontal force is obtained by taking moments about that point of rotation The program then constructs shearing force and bending moment diagrams The bending moments shear forces and soil reaction diagrams are reported on the single page of output which would normally be printed by a user of the program Page 18 JV STEWART TECHNOLOGY ASSOCIATES JH GTA PILES USER MANUAL WWww stewart usa com USA and Caribbean Version 1 8 December 2009 8 0 PILE STRESSES Having found the bending moments in the pile the program calculates bending stresses and reports the maximum bending stress in response to the ultimate horizontal load that the pile can resist The program also reports the bending stress in response to the user specified applied horizontal load Additionally the program reports axial stresses in response to the vertical loads The program determines the ultimate vertical upwards load that the pile can carry and the maximum axial stress that this will cause It reports this value as well as the maximum axial stress in response to the user specified vertical load as shown in Figure 12 0 00 cus undrained sh strength top 3rd layer psf 24 35 Horizontal load safety factor Explain value 0 00 cu undrained sh strength bo
24. ight OCP rrrronrerrnnnerrnnnrrrannerrnnrerrnnrennnnrennnnrrnnnnnnn 23 Gamma2 2nd layer buoyant weight Cf cccceecccsseceeseeceseeeeesseeceeseeeesaaseeseaeeeeas 23 Gammad3 3rd layer buoyant weight Cf ccccccececceeeeeseeeeseeeeesseeesseeeesseeeesaaeeeeas 23 Fy Yield stress for pile Steel KSI ccccccccseeccceeeeseeeeeeeeeseeeeseeeeseeeesaeeesaeeeseeeeseeeenees 23 ztop top to seabed ve If buried Mcee 23 ZC dist pile head to pad eye ft ccccsecccsecccececeececeececeeeeceeeeceeeecsueecsueecsaeesseeesseeesas 23 ED G 23 L DUE Wall TNEKNESS INCMCS reece cccescsevecisvecinnsenssesosereusresesevencsesueasavensseuuserduensveeseveseds 24 E Young s Modulus pile PSI cece eeeccseeeeeeeeeeeeeeseeeeaeeeeseeeesaeeeseeeeseeeeseeeseeeeseeeesees 24 Hmax applied lateral load Kip cccccsecccseeeceeeeeeeeeseeeeseeeeseeeseeeseeeeseueesaueeseneesaees 24 Vmax applied vert load ve up kip ccceececeeceeeeeeeeeeeseeeeseeeeseeeeseeeeseeesaeeeseaeeeas 24 pile mass density lb cuft Lue eee edel 24 NO FEIE DINE ve 24 DiS TOD TICKS 1M ccaceunatescenegancdsanqanecaancsmecsannaaeteanaauonsanetenaenagnuseneainedaanaamodsazesaensacne 24 CUTUGNO EEE 25 SUCTION embedment analysis rararranrrranernanerranerranennanennanennanennanennanennanennusennasennunene 25 JH STA PILE3 USER MANUAL Version 1 8 December 2009 1 0 INTRODUCTION STA PILE3 is a program for the
25. is cu1 undrained sh strength top 1st layer psf E Young s Modulus pile psi 1 closed end 2 open cu2 undrained sh strength bottom 1st layer psf 35 Hmax applied lateral load kip cu switch 1 psi 2 old API method cu3 undrained sh strength top 2nd layer psf 17 Vmax applied vert load ve up kip 1 underconsol 2 normal cu4 undrained sh strength bottom 2nd layer psf cu5 undrained sh strength top 3rd layer psf 1 01 Horizontal load safety factor Explain value cu6 undrained sh strength bottom 3rd layer psf 3 14 Vertical load safety factor Gammal st layer buoyant weight pcf 0 40 Unity stress check app loads Gammaz2 2nd layer buoyant weight pcf 1 61 Ult capacity unity check Meyerhof Gamma3 3rd layer buoyant weight pcf open Short pile criteria probably OK FIGURE 3 The spreadsheet will always contain values in every editable cell It is recommended that following an analysis with the program you save the spreadsheet before closing down the application You should begin each new analysis by clicking on the button Select Analysis Type and Applied Loads A dialog box will open in which you can select the type of analysis you wish to perform The choices are nstalled Pile Capacity Analysis or Suction Embedment Analysis In this dialog box you will also be able to define the loads to be applied to the pile in an installed pile capacity analysis
26. kness inches This is the thickness of the pile wall in inches The pile is assumed to have uniform wall thickness throughout its length All piles are modeled as uniform cylinders E Young s Modulus pile psi This is the Young s Modulus for the pile material Units are in pounds force per square inch A typical value for steel is 30 000 000 psi A typical value for concrete is 3 500 000 psi This term is used in calculating the relative pile soil stiffness term see below Hmax applied lateral load kip This is the horizontal applied load to the pad eye Units are kips This term is specified by the user in a dialog box which is activated by clicking on the button Select Analysis Type and Apply Loads Vmax applied vert load ve up kip This is the applied vertical load at the pile pad eye Units are kips If the pile is to be analyzed for uplift capacity this term will be positive If the pile is to be analyzed for vertically downwards applied loads this term will be negative This term is input by the using by clicking on the button Select Analysis Type and Apply Loads Note that if the User has selected to analyze suction embedment Hmax see above will be set to zero and Vmax will be set to the calculated load required to cause suction embedment pile mass density Ib cuft This is the mass density of the pile material Units are pounds mass per cubic foot This term is used to calculate the submerged weight of the pile n
27. l Useful in Pile Desgn Standard friction relative buoyant Penetration angle density unt eight Type Blow Count N degrees nercentage acf medium dense 10 20 51 30 io Seems sere Copyuriokl Steve Technology Associates 1992 and onwards For supmortielephone fF 75 oS 53417 or fax 273 89 0574 Table 5 3 2 From Navy Geotechnical Handbook Properties of Cohesive Soils Useful in Pile Design undrained shear strength buoyant Su epslondd unit w eight Type percentage act underconsoldated clays Moaes 1A at 180 Ale 25 al alao aa a sails at depth 7 inches 1 0 000337 144 5 7 ff 2 1 25 50 overconsolidated solls based on consistency S00 1000 1 WeDo 1000 2000 Of SU 65 FIGURE 9 JV STEWART TECHNOLOGY ASSOCIATES JH GTA PILES USER MANUAL Wwww stewart usa com USA and Caribbean Version 1 8 December 2009 Table 6 4 3 1 from API RP 2A 70th Edition 1993 Design Parameters for Cohesionless Siliceous Soils Sol Hle Limiting Unit Friction Limiting Skin End Bearing Sol Angle delta Friction Values Values Densi Description De Very Loose Sand At Loose Sand SIK Medium Silt Loose Sand Medium Sand Sit Lense Silt Lense Sand Silt Very Dense Sand silt Dense 1148 Very Dense Sand 1148 The parameters leted n thie table are intended as guidelines Cand Sk indudesthose aik wth sgnticant fractions of onk Where detaled nforrmton such asin atu cone tests both sand and at Strength valies gener
28. mber 2009 The value for the ultimate capacity unity check UCUC is Found From the Following LEUE iHi Hulo Az DAA x 1 5 where H applied horizontal load Hulk ultimate horizontal capacity in absence of vertical loading Y applied vertical load Wolk ultimate vertical capacity lin absence of horizontal loading It can be seen that if H Hult and vult then UCUC 3 0 If the Factors of safety For both horizontal and vertical Failures are both 1 5 then UCUE 2 x 111 512 1 33 IF both vertical and horizontal Factors of safety against Failure are 1 73 the UCUC is equal to 1 0 The UCUC is one way of assessing the adequacy of pile anchors subject to combined loads FIGURE 7 If the user selects a cell for which there is no help available a dialog box will be flashed up on the screen suggesting that the cursor is repositioned in another cell An example of this is shown in Figure 8 No help available For this cell Place cursor in data input cell or in results value cell then click on explain button Ok FIGURE 8 Two tables of useful data are built into the program and can be viewed by clicking on the API Cohesionless Soil Parameters button or the Navy Soil Design Parameters button The tables are shown in figures 9 and 10 De ee eee WwWww stewart usa com USA and Caribbean Version 1 8 December 2009 Table 5 3 1 From Navy Geotechnical Handbook Properties of Cohesionless Soi
29. o radial bulkheads The User may specify as many radial bulkheads as desired If the User specifies zero there will be no radial bulkheads If the User specifies a value a 2 the program will assume that there is a central vertical bulkhead extending across the diameter of the pile If the User specifies 3 the program will calculate three radial bulkheads spaced as 120 degrees If the User specifies 1 the program will assume that vertical stiffeners within the pile exist For each of the radial bulkheads or stiffeners the program will calculate weight increased tip resistance to penetration and internal skin friction pile top thickness in This term is the thickness of a top which the User may specify on the pile Units are in inches The top will contribute weight to the pile The User may adjust the thickness to account for additional equipment on the top of a suction pile The pile mass density is used in calculating the weight of the pile top Page 24 JH STA PILE3 USER MANUAL Version 1 8 December 2009 cu reduction factor This term is used to multiply the undisturbed undrained shear strength of each layer A cu reduction factor of 0 5 means that the actual undrained strength of the soil used in resistance and pullout calculations will be 50 of that input by the User A cu reduction factor of 0 75 means that the actual undrained shear strength of the soil will be 75 of that specified by the User Suction embedment analysi
30. ram is for the pile to rotate about some point within its length as a consequence of the lateral load or to pull upwards as a consequence of the vertical component of load applied to the pile These failure mechanisms are illustrated in Figure 1 below In the case for a vertical pile unrestrained at the head subjected to a lateral load at the pile head the lateral loading is initially carried by the soil close to the ground surface As the load at the pile head is increased the soil compresses elastically but the movement is sufficient to transfer some pressure from the pile to the soil at greater depth Eventually the soil yields plastically and transfers loads to greater depth still This program is for short rigid piles Length to width ratios should be less than 12 At the ultimate capacity load applied horizontally to the pile head the pile will rotate and fail the soil plastically A passive resistance develops above the toe on the opposite face of the pile adding to the resistance of the soil further up the pile towards the ground surface Failure occurs when the passive resistance of the soil at the head and the toe are exceeded JV STEWART TECHNOLOGY ASSOCIATES JH GTA PILES USER MANUAL WwwWww stewart usa com USA and Caribbean Version 1 8 December 2009 STA PILE BASIC ASSUMPTIONS AND ANALYSIS APPROACH The diagram below shows the basic Failure mechanisms considered in STA FILE Horizontal capacity is governed by rotational Failur
31. s In earlier versions of the program this switch had to be set by the User The term is now automatically set when the User clicks on the button Select Analysis Type and Apply Loads The User is given two options in a dialog box that will appear The first option is to perform and installed analysis The second option is to perform a suction embedment analysis This term will be set to 1 if suction embedment is selected or 2 if installed analysis is selected If it is desired to determine the penetration resistance of a driven closed ended pile this switch should be set to 1 Where a closed ended pile is specfied the analysis will assume that the pile is filled with water both during driving and during pullout resistance calcuations If the User specifies an closed ended pile by setting this switch to 1 and then selects to perform a suction embedment analysis the program will issue a warning In the psi method the friction force is This term is a selection switch which sets alpha 1 0 in the calculation of pile skin friction using the API RP 2A 19th Edition psi method This effectively sets f cu which is appropriate for underconsolidated Page 25
32. s are specified for any soil layer Phi2 2nd layer friction angle deg This is the friction angle to be used in the analysis for the second soil layer Comments as for Phi1 apply Phi3 3rd layer friction angle deg This is the third layer friction angle Comments as for Phi1 apply cul undrained sh strength top 1st layer psf This is the UNDISTURBED undrained shear strength for the soil at the top of the first layer in other words at the sea bed Units are in pounds force per square foot cu2 undrained sh strength bottom 1st layer psf This is the UNDISTURBED undrained shear strength for the soil at the bottom of the first layer in other words at the sea bed Units are in pounds force per square foot The undrained shear strength is considered to vary in a linear manner between the top and bottom of each layer cu3 undrained sh strength top 2nd layer psf This is the undrained shear strength for the soil at the top of the second layer in other words at the sea bed Units are in pounds force per square foot Page 22 www stewart uSa cOM USA and Caribbean Version 1 8 December 2009 cu4 undrained sh strength bottom 2nd layer psf Comments as for cu2 apply cu5 undrained sh strength top 3rd layer psf Comments as for cul apply cu6 undrained sh strength bottom 3rd layer psf Comments as for cu2 apply Note that if the pile is specified as being embedded with its bottom beneath the third soil layer
33. s license The PROGRAM and its documentation is sold as is and the USER assumes the entire risk as to quality and performance HOLD HARMLESS The OWNER shall not be liable to the USER or any other party for any design performance or other fault or inadequacy of the PROGRAM or its manual or for any direct or implied damages of any kind arising out of or in any way related to or connected with any use of the PROGRAM www stewart uSa cOM USA and Caribbean Version 1 8 December 2009 Subject Paget Contents 1 0 INTRODUCTION eenuvronnenranrerranrernansernnnsennnnsnnnnnennnnnennnnnennansennansennansennunsennunsennnneene 1 2 0 FARENE ANN 2 3 0 SPECIAL CONDITIONS AT PILE ANCHORS rurrarnrnnnrrennanrennnnnnnnansnnnnnsnnnnnnnnnnner 4 4 0 PROGRAM INSTALLATION vm 5 Al ON 5 4 2 Install Files and Create Directories rrrrarrrrrannrrrnnnerrnnnennnnnennnnrennnnnnnnnrrnnnnennnnn 5 Aso MN 5 50 FUNNN REPR Fv 7 60 EINER ph 9 7 0 BASIC ANALYSIS ASSUMPTIONS vvs eee 13 7 1 StiffMESS Factors rrarrrrarerrarerrarerranerranerranennanennanennanennanennanennanennanennunennunennunene 13 2 VE 14 7 3 Ultimate Resistance To Horizontal Loading ranrnnnnrrnnevnnrnnnnnnanrnnnrnnnnnnnnennnen 16 Go EEE NN seaten seepage eats 16 GSE ene oe ee ene 16 EN SG 0 17 Rotational Failure Calculations uavssegssssseanenandegmanenntgtdeateau 17 80 PETERSEN eee 19 REFERENCE irae cy carat ce dirs go cade tacts E EA 20 PP 14444444 21 DEFINITION
34. shaft friction f is found from the equation f Kp tan d Where K is the coefficient of lateral earth pressure po is the effective overburden pressure and d is the friction angle between the soil and the pile wall The value of K is taken to be 1 in the program as the pile is assumed to be closed end The value of d is taken from Table 6 4 3 1 in Reference 3 The limiting values for f given in this table are also applied in STA PILES Page 14 JH STA PILE3 USER MANUAL Version 1 8 December 2009 If the vertical component of loading applied to the pile is upwards shaft friction on the outside of the pile only is considered However if the vertical loading is downwards STA PILES considers internal shaft friction if the pile is specified as open ended or the end bearing of the plug whichever is less as well as the end bearing of the pile wall annulus If the pile is specified as closed end the end bearing of the full cross section is calculated The equations for end bearing are taken from API RP 2A Reference 1 with coefficients and limiting values from Table 6 4 3 1 in this reference The user of STA PILE3 is cautioned to use care in selecting the soil properties for analysis The user is advised to consult Reference 1 The user can see a graph of skin friction down the pile by clicking once on the Friction button An example is shown in Figure 11 below External Friction Inactive Subs compact gravel at 40 fl 10 298 9
35. ttom 3rd layer psf 2 48 Vertical load safety factor 35 00 Gammat 1st layer buoyant weight pef O24 Unity stress check app loads 70 00 Gammad 2nd layer buoyant weight pef 70 00 Gamma3 3rd layer buoyant weight pef open Rotation center shown as blue dot Pile Elevation layer 3 20707 imax we BRA fror Hult fkip 113 20 Max combined stress in pile in kei from ult Io Explain value Select Analysis Type and or Change Applied Loads padeye shown and depth in feet orizontal Soil Reactions kiput 50000 20000 10000 oO 10000 5000 1500 1000 500 a oO 0 0 Depth tin Depth in www stewart uSa cOM USA and Caribbean Version 1 8 December 2009 REFERENCES 1 Recommended Practice For Planning Designing And Constructing Fixed Offshore Platforms API Recommended Practice 2A RP 2A 19th Edition August 1 1991 2 Handbook For Marine Geotechnical Engineering Technical Editor Rocker K March 1985 available from Naval Civil Engineering Laboratory Port Hueneme California 93043 3 Meyerhof G G and Ranjan G The Bearing Capacity of Rigid Piles Under Inclined Loads in Sand I Vertical Piles Canadian Geotechnical Journal Vol 9 1972 pp 430 446 Page 20 JH STA PILE3 USER MANUAL Version 1 8 December 2009 APPENDIX 1 DEFINITION OF INPUT DATA This Appendix lists each of the input data terms that the user may edit Note that by placing the cursor on
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