EX. US-21 Analysis of a Structure with Tension-Only Members
This example illustrates the modeling of tension-only members using the MEMBER TENSION command.
This problem is installed with the program by default to C:\Users\Public\Public Documents\STAAD.Pro CONNECT Edition\Samples\Sample Models\US\US-21 Analysis of a Structure with Tension-Only Members.STD when you install the program.
It is important to note that the analysis can be done for only 1 load case at a time. This is because, the set of "active" members (and hence the stiffness matrix) is load case dependent.
where:
- L = 15 ft, H = 10 ft
- Load case 1: P1 = 10 kips & P2 = 15 kips
- Load case 2: P3 = -10 kips & P4 = -15 kips
STAAD PLANE EXAMPLE FOR TENSION-ONLY MEMBERS
The input data is initiated with the word STAAD. This structure is a PLANE frame.
UNIT FEET KIP
Units for the commands to follow are defined above.
JOINT COORDINATES
1 0 0 ; 2 0 10 ; 3 0 20 ; 4 15 20 ; 5 15 10 ; 6 15 0
Joint coordinates of joints 1 to 6 are defined above.
MEMBER INCIDENCES
1 1 2 5
6 1 5 ; 7 2 6 ; 8 2 4 ; 9 3 5 ; 10 2 5
Incidences of members 1 to 10 are defined.
MEMBER TENSION
6 TO 9
Members 6 to 9 are defined as tension-only members using the MEMBER TENSION command. Hence for each load case, if during the analysis, any of the members 6 to 9 is found to be carrying a compressive force, it is disabled from the structure and the analysis is carried out again with the modified structure.
MEMBER PROPERTY AMERICAN
1 TO 10 TA ST W12X26
All members have been assigned a WIDE FLANGE section from the built in American table.
UNIT INCH
DEFINE MATERIAL START
ISOTROPIC STEEL
E 29000
POISSON 0.3
DENSITY 283e-006
ALPHA 6e-006
DAMP 0.03
TYPE STEEL
STRENGTH FY 36 FU 58 RY 1.5 RT 1.2
END DEFINE MATERIAL
CONSTANT
MATERIAL STEEL ALL
The DEFINE MATERIAL command is used to specify material properties and the CONSTANT is used to assign the material to all members. The length units have been changed from feet to inch to facilitate the input of these values.
SUPPORT
1 6 PINNED
The supports are defined above.
MEMBER TENSION
6 TO 9
One or more among the members 6 to 9 may have been inactivated in the analysis.
LOAD 1
JOINT LOAD
2 FX 15
3 FX 10
Load 1 is defined above and consists of joint loads at joints 2 and 3.
LOAD 2
JOINT LOAD
4 FX -10
5 FX -15
Load case 2 is described above.
LOAD 3
REPEAT LOAD
1 1.0 2 1.0
Load case 3 illustrates the technique employed to instruct STAAD to create a load case which consists of data to be assembled from other load cases already specified earlier. We would like the program to analyze the structure for loads from cases 1 and 2 acting simultaneously.
PRINT ANALYSIS RESULTS
FINI
The analysis results are printed and the run terminated.
Input File
STAAD PLANE EXAMPLE FOR TENSION-ONLY MEMBERS
UNIT FEET KIP
SET NL 3
JOINT COORDINATES
1 0 0 ; 2 0 10 ; 3 0 20 ; 4 15 20 ; 5 15 10 ; 6 15 0
MEMBER INCIDENCES
1 1 2 5
6 1 5 ; 7 2 6 ; 8 2 4 ; 9 3 5 ; 10 2 5
MEMBER TENSION
6 TO 9
MEMBER PROPERTY AMERICAN
1 TO 10 TA ST W12X26
UNIT INCH
DEFINE MATERIAL START
ISOTROPIC STEEL
E 29000.0
POISSON 0.3
DENSITY 283e-006
ALPHA 6e-006
DAMP 0.03
TYPE STEEL
STRENGTH FY 36 FU 58 RY 1.5 RT 1.2
END DEFINE MATERIAL
CONSTANT
MATERIAL STEEL ALL
SUPPORT
1 PINNED
6 PINNED
LOAD 1
JOINT LOAD
2 FX 15
3 FX 10
PERFORM ANALYSIS
CHANGE
MEMBER TENSION
6 TO 9
LOAD 2
JOINT LOAD
4 FX -10
5 FX -15
PERFORM ANALYSIS
CHANGE
MEMBER TENSION
6 TO 9
LOAD 3
REPEAT LOAD
1 1.0 2 1.0
PERFORM ANALYSIS
CHANGE
LOAD LIST ALL
PRINT ANALYSIS RESULTS
FINI
STAAD Output File
PAGE NO. 1 **************************************************** * * * STAAD.Pro CONNECT Edition * * Version 22.12.00.*** * * Proprietary Program of * * Bentley Systems, Inc. * * Date= OCT 27, 2022 * * Time= 15: 9:32 * * * * Licensed to: Bentley Systems Inc * **************************************************** 1. STAAD PLANE EXAMPLE FOR TENSION-ONLY MEMBERS INPUT FILE: US-21 Analysis of a Structure with Tension-Only Members.STD 2. UNIT FEET KIP 3. SET NL 3 4. JOINT COORDINATES 5. 1 0 0 ; 2 0 10 ; 3 0 20 ; 4 15 20 ; 5 15 10 ; 6 15 0 6. MEMBER INCIDENCES 7. 1 1 2 5 8. 6 1 5 ; 7 2 6 ; 8 2 4 ; 9 3 5 ; 10 2 5 9. MEMBER TENSION 10. 6 TO 9 11. MEMBER PROPERTY AMERICAN 12. 1 TO 10 TA ST W12X26 13. UNIT INCH 14. DEFINE MATERIAL START 15. ISOTROPIC STEEL 16. E 29000.0 17. POISSON 0.3 18. DENSITY 283E-006 19. ALPHA 6E-006 20. DAMP 0.03 21. TYPE STEEL 22. STRENGTH FY 36 FU 58 RY 1.5 RT 1.2 23. END DEFINE MATERIAL 24. CONSTANT 25. MATERIAL STEEL ALL 26. SUPPORT 27. 1 PINNED 28. 6 PINNED 29. LOAD 1 30. JOINT LOAD 31. 2 FX 15 32. 3 FX 10 33. PERFORM ANALYSIS EXAMPLE FOR TENSION-ONLY MEMBERS -- PAGE NO. 2 P R O B L E M S T A T I S T I C S ----------------------------------- NUMBER OF JOINTS 6 NUMBER OF MEMBERS 10 NUMBER OF PLATES 0 NUMBER OF SOLIDS 0 NUMBER OF SURFACES 0 NUMBER OF SUPPORTS 2 Using 64-bit analysis engine. SOLVER USED IS THE IN-CORE ADVANCED MATH SOLVER TOTAL PRIMARY LOAD CASES = 1, TOTAL DEGREES OF FREEDOM = 14 TOTAL LOAD COMBINATION CASES = 0 SO FAR. *** LOAD CASE 1 -- START ITERATION NO. 2 **NOTE-Tension/Compression converged after 2 iterations, Case= 1 34. CHANGE 35. MEMBER TENSION 36. 6 TO 9 37. LOAD 2 38. JOINT LOAD 39. 4 FX -10 40. 5 FX -15 41. PERFORM ANALYSIS *** LOAD CASE 2 -- START ITERATION NO. 2 **NOTE-Tension/Compression converged after 2 iterations, Case= 2 42. CHANGE 43. MEMBER TENSION 44. 6 TO 9 45. LOAD 3 46. REPEAT LOAD 47. 1 1.0 2 1.0 48. PERFORM ANALYSIS *** LOAD CASE 3 -- START ITERATION NO. 2 **NOTE-Tension/Compression converged after 2 iterations, Case= 3 EXAMPLE FOR TENSION-ONLY MEMBERS -- PAGE NO. 3 49. CHANGE 50. LOAD LIST ALL 51. PRINT ANALYSIS RESULTS ANALYSIS RESULTS EXAMPLE FOR TENSION-ONLY MEMBERS -- PAGE NO. 4 JOINT DISPLACEMENT (INCH RADIANS) STRUCTURE TYPE = PLANE ------------------ JOINT LOAD X-TRANS Y-TRANS Z-TRANS X-ROTAN Y-ROTAN Z-ROTAN 1 1 0.00000 0.00000 0.00000 0.00000 0.00000 -0.00062 2 0.00000 0.00000 0.00000 0.00000 0.00000 0.00039 3 0.00000 0.00000 0.00000 0.00000 0.00000 -0.00007 2 1 0.06285 0.00373 0.00000 0.00000 0.00000 -0.00030 2 -0.04313 -0.01262 0.00000 0.00000 0.00000 0.00028 3 0.00605 0.00000 0.00000 0.00000 0.00000 -0.00001 3 1 0.09724 0.00387 0.00000 0.00000 0.00000 -0.00018 2 -0.08929 -0.01613 0.00000 0.00000 0.00000 0.00029 3 0.00408 0.00000 0.00000 0.00000 0.00000 0.00002 4 1 0.08929 -0.01613 0.00000 0.00000 0.00000 -0.00029 2 -0.09724 0.00387 0.00000 0.00000 0.00000 0.00018 3 -0.00408 0.00000 0.00000 0.00000 0.00000 -0.00002 5 1 0.04313 -0.01262 0.00000 0.00000 0.00000 -0.00028 2 -0.06285 0.00373 0.00000 0.00000 0.00000 0.00030 3 -0.00605 0.00000 0.00000 0.00000 0.00000 0.00001 6 1 0.00000 0.00000 0.00000 0.00000 0.00000 -0.00039 2 0.00000 0.00000 0.00000 0.00000 0.00000 0.00062 3 0.00000 0.00000 0.00000 0.00000 0.00000 0.00007 EXAMPLE FOR TENSION-ONLY MEMBERS -- PAGE NO. 5 SUPPORT REACTIONS -UNIT KIP INCH STRUCTURE TYPE = PLANE ----------------- JOINT LOAD FORCE-X FORCE-Y FORCE-Z MOM-X MOM-Y MOM Z 1 1 -24.91 -23.33 0.00 0.00 0.00 0.00 2 0.09 23.33 0.00 0.00 0.00 0.00 3 -0.05 0.00 0.00 0.00 0.00 0.00 6 1 -0.09 23.33 0.00 0.00 0.00 0.00 2 24.91 -23.33 0.00 0.00 0.00 0.00 3 0.05 0.00 0.00 0.00 0.00 0.00 EXAMPLE FOR TENSION-ONLY MEMBERS -- PAGE NO. 6 MEMBER END FORCES STRUCTURE TYPE = PLANE ----------------- ALL UNITS ARE -- KIP INCH (LOCAL ) MEMBER LOAD JT AXIAL SHEAR-Y SHEAR-Z TORSION MOM-Y MOM-Z 1 1 1 -6.90 0.26 0.00 0.00 0.00 0.00 2 6.90 -0.26 0.00 0.00 0.00 31.66 2 1 23.33 -0.09 0.00 0.00 0.00 -0.00 2 -23.33 0.09 0.00 0.00 0.00 -10.81 3 1 0.00 0.05 0.00 0.00 0.00 0.00 2 -0.00 -0.05 0.00 0.00 0.00 5.46 2 1 2 -0.24 0.20 0.00 0.00 0.00 6.07 3 0.24 -0.20 0.00 0.00 0.00 18.42 2 2 6.49 -0.43 0.00 0.00 0.00 -25.74 3 -6.49 0.43 0.00 0.00 0.00 -25.59 3 2 0.00 -0.05 0.00 0.00 0.00 -4.66 3 -0.00 0.05 0.00 0.00 0.00 -1.39 3 1 3 9.80 -0.24 0.00 0.00 0.00 -18.42 4 -9.80 0.24 0.00 0.00 0.00 -25.59 2 3 9.80 0.24 0.00 0.00 0.00 25.59 4 -9.80 -0.24 0.00 0.00 0.00 18.42 3 3 10.05 0.00 0.00 0.00 0.00 1.39 4 -10.05 -0.00 0.00 0.00 0.00 -1.39 4 1 4 6.49 0.43 0.00 0.00 0.00 25.59 5 -6.49 -0.43 0.00 0.00 0.00 25.74 2 4 -0.24 -0.20 0.00 0.00 0.00 -18.42 5 0.24 0.20 0.00 0.00 0.00 -6.07 3 4 -0.00 0.05 0.00 0.00 0.00 1.39 5 0.00 -0.05 0.00 0.00 0.00 4.66 5 1 5 23.33 0.09 0.00 0.00 0.00 10.81 6 -23.33 -0.09 0.00 0.00 0.00 0.00 2 5 -6.90 -0.26 0.00 0.00 0.00 -31.66 6 6.90 0.26 0.00 0.00 0.00 0.00 3 5 -0.00 -0.05 0.00 0.00 0.00 -5.46 6 0.00 0.05 0.00 0.00 0.00 0.00 6 1 1 -29.62 0.00 0.00 0.00 0.00 0.00 5 29.62 0.00 0.00 0.00 0.00 0.00 2 1 0.00 0.00 0.00 0.00 0.00 0.00 5 0.00 0.00 0.00 0.00 0.00 0.00 3 1 0.00 0.00 0.00 0.00 0.00 0.00 5 0.00 0.00 0.00 0.00 0.00 0.00 7 1 2 0.00 0.00 0.00 0.00 0.00 0.00 6 0.00 0.00 0.00 0.00 0.00 0.00 EXAMPLE FOR TENSION-ONLY MEMBERS -- PAGE NO. 7 MEMBER END FORCES STRUCTURE TYPE = PLANE ----------------- ALL UNITS ARE -- KIP INCH (LOCAL ) MEMBER LOAD JT AXIAL SHEAR-Y SHEAR-Z TORSION MOM-Y MOM-Z 2 2 -29.62 0.00 0.00 0.00 0.00 0.00 6 29.62 0.00 0.00 0.00 0.00 0.00 3 2 0.00 0.00 0.00 0.00 0.00 0.00 6 0.00 0.00 0.00 0.00 0.00 0.00 8 1 2 -11.26 0.00 0.00 0.00 0.00 0.00 4 11.26 0.00 0.00 0.00 0.00 0.00 2 2 0.00 0.00 0.00 0.00 0.00 0.00 4 0.00 0.00 0.00 0.00 0.00 0.00 3 2 0.00 0.00 0.00 0.00 0.00 0.00 4 0.00 0.00 0.00 0.00 0.00 0.00 9 1 3 0.00 0.00 0.00 0.00 0.00 0.00 5 0.00 0.00 0.00 0.00 0.00 0.00 2 3 -11.26 0.00 0.00 0.00 0.00 0.00 5 11.26 0.00 0.00 0.00 0.00 0.00 3 3 0.00 0.00 0.00 0.00 0.00 0.00 5 0.00 0.00 0.00 0.00 0.00 0.00 10 1 2 24.31 -0.41 0.00 0.00 0.00 -37.72 5 -24.31 0.41 0.00 0.00 0.00 -36.55 2 2 24.31 0.41 0.00 0.00 0.00 36.55 5 -24.31 -0.41 0.00 0.00 0.00 37.72 3 2 14.90 0.00 0.00 0.00 0.00 -0.79 5 -14.90 -0.00 0.00 0.00 0.00 0.79 ************** END OF LATEST ANALYSIS RESULT ************** 52. FINI EXAMPLE FOR TENSION-ONLY MEMBERS -- PAGE NO. 8 *********** END OF THE STAAD.Pro RUN *********** **** DATE= OCT 27,2022 TIME= 15: 9:33 **** ************************************************************ * For technical assistance on STAAD.Pro, please visit * * http://www.bentley.com/en/support/ * * * * Details about additional assistance from * * Bentley and Partners can be found at program menu * * Help->Technical Support * * * * Copyright (c) Bentley Systems, Inc. * * http://www.bentley.com * ************************************************************