EX. UK-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\UK\UK-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 = 5.25 m, H = 3.5 m
- Load case 1: P1 = 45 kN & P2 = 70 kN
- Load case 2: P3 = -45 kN & P4 = -70 kN
STAAD PLANE EXAMPLE FOR TENSION-ONLY MEMBERS
The input data is initiated with the word STAAD. This structure is a PLANE frame.
UNIT METER KNS
Units for the commands to follow are defined above.
JOINT COORDINATES
1 0 0 ; 2 0 3.5 ; 3 0 7.0 ; 4 5.25 7.0 ; 5 5.25 3.5 ; 6 5.25 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 BRITISH
1 TO 10 TA ST UC152X152X30
All members have been assigned a UC section from the British table.
UNIT MMS
DEFINE MATERIAL START
ISOTROPIC STEEL
E 210
POISSON 0.3
DENSITY 7.6977e-008
ALPHA 6e-006
DAMP 0.03
TYPE STEEL
STRENGTH FY 0.24821 FU 0.399894 RY 1.5 RT 1.2
END DEFINE MATERIAL
CONSTANTS
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 meters to millimeters to facilitate the input of these values.
SUPPORT
1 6 PINNED
The supports are defined above.
LOAD 1
JOINT LOAD
2 FX 70
3 FX 45
Load 1 is defined above and consists of joint loads at joints 2 and 3.
PERFORM ANALYSIS
CHANGE
MEMBER TENSION
6 TO 9
One or more among the members 6 to 9 may have been inactivated in the previous analysis.
LOAD 2
JOINT LOAD
4 FX -45
5 FX -70
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 METER KNS
SET NL 3
JOINT COORDINATES
1 0 0 ; 2 0 3.5 ; 3 0 7.0 ; 4 5.25 7.0 ; 5 5.25 3.5 ; 6 5.25 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 BRITISH
1 TO 10 TABLE ST UC152X152X30
UNIT MMS
DEFINE MATERIAL START
ISOTROPIC STEEL
E 210
POISSON 0.3
DENSITY 7.6977e-008
ALPHA 6e-006
DAMP 0.03
TYPE STEEL
STRENGTH FY 0.24821 FU 0.399894 RY 1.5 RT 1.2
END DEFINE MATERIAL
CONSTANTS
MATERIAL STEEL ALL
SUPPORT
1 6 PINNED
LOAD 1
JOINT LOAD
2 FX 70
3 FX 45
PERFORM ANALYSIS
CHANGE
MEMBER TENSION
6 TO 9
LOAD 2
JOINT LOAD
4 FX -45
5 FX -70
PERFORM ANALYSIS
CHANGE
LOAD 3
REPEAT LOAD
1 1.0 2 1.0
PERFORM ANALYSIS
CHANGE
LOAD LIST 1 2 3
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: 7:40 * * * * Licensed to: Bentley Systems Inc * **************************************************** 1. STAAD PLANE EXAMPLE FOR TENSION-ONLY MEMBERS INPUT FILE: UK-21 Analysis of a Structure with Tension-Only Members.STD 2. UNIT METER KNS 3. SET NL 3 4. JOINT COORDINATES 5. 1 0 0 ; 2 0 3.5 ; 3 0 7.0 ; 4 5.25 7.0 ; 5 5.25 3.5 ; 6 5.25 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 BRITISH 12. 1 TO 10 TABLE ST UC152X152X30 13. UNIT MMS 14. DEFINE MATERIAL START 15. ISOTROPIC STEEL 16. E 210 17. POISSON 0.3 18. DENSITY 7.6977E-008 19. ALPHA 6E-006 20. DAMP 0.03 21. TYPE STEEL 22. STRENGTH FY 0.24821 FU 0.399894 RY 1.5 RT 1.2 23. END DEFINE MATERIAL 24. CONSTANTS 25. MATERIAL STEEL ALL 26. SUPPORT 27. 1 6 PINNED 28. LOAD 1 29. JOINT LOAD 30. 2 FX 70 31. 3 FX 45 32. 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 33. CHANGE 34. MEMBER TENSION 35. 6 TO 9 36. LOAD 2 37. JOINT LOAD 38. 4 FX -45 39. 5 FX -70 40. PERFORM ANALYSIS *** LOAD CASE 2 -- START ITERATION NO. 2 **NOTE-Tension/Compression converged after 2 iterations, Case= 2 41. CHANGE 42. LOAD 3 43. REPEAT LOAD 44. 1 1.0 2 1.0 45. PERFORM ANALYSIS *** LOAD CASE 3 -- START ITERATION NO. 2 **NOTE-Tension/Compression converged after 2 iterations, Case= 3 46. CHANGE 47. LOAD LIST 1 2 3 EXAMPLE FOR TENSION-ONLY MEMBERS -- PAGE NO. 3 48. PRINT ANALYSIS RESULTS ANALYSIS RESULTS EXAMPLE FOR TENSION-ONLY MEMBERS -- PAGE NO. 4 JOINT DISPLACEMENT (CM RADIANS) STRUCTURE TYPE = PLANE ------------------ JOINT LOAD X-TRANS Y-TRANS Z-TRANS X-ROTAN Y-ROTAN Z-ROTAN 1 1 0.0000 0.0000 0.0000 0.0000 0.0000 -0.0008 2 0.0000 0.0000 0.0000 0.0000 0.0000 0.0005 3 0.0000 0.0000 0.0000 0.0000 0.0000 -0.0001 2 1 0.2355 0.0132 0.0000 0.0000 0.0000 -0.0004 2 -0.1609 -0.0464 0.0000 0.0000 0.0000 0.0004 3 0.0228 0.0000 0.0000 0.0000 0.0000 -0.0000 3 1 0.3633 0.0133 0.0000 0.0000 0.0000 -0.0002 2 -0.3341 -0.0594 0.0000 0.0000 0.0000 0.0004 3 0.0147 0.0000 0.0000 0.0000 0.0000 0.0000 4 1 0.3341 -0.0594 0.0000 0.0000 0.0000 -0.0004 2 -0.3633 0.0133 0.0000 0.0000 0.0000 0.0002 3 -0.0147 0.0000 0.0000 0.0000 0.0000 -0.0000 5 1 0.1609 -0.0464 0.0000 0.0000 0.0000 -0.0004 2 -0.2355 0.0132 0.0000 0.0000 0.0000 0.0004 3 -0.0228 0.0000 0.0000 0.0000 0.0000 0.0000 6 1 0.0000 0.0000 0.0000 0.0000 0.0000 -0.0005 2 0.0000 0.0000 0.0000 0.0000 0.0000 0.0008 3 0.0000 0.0000 0.0000 0.0000 0.0000 0.0001 EXAMPLE FOR TENSION-ONLY MEMBERS -- PAGE NO. 5 SUPPORT REACTIONS -UNIT KNS MMS STRUCTURE TYPE = PLANE ----------------- JOINT LOAD FORCE-X FORCE-Y FORCE-Z MOM-X MOM-Y MOM Z 1 1 -114.92 -106.67 0.00 0.00 0.00 0.00 2 0.08 106.67 0.00 0.00 0.00 0.00 3 -0.05 0.00 0.00 0.00 0.00 0.00 6 1 -0.08 106.67 0.00 0.00 0.00 0.00 2 114.92 -106.67 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 -- KNS MMS (LOCAL ) MEMBER LOAD JT AXIAL SHEAR-Y SHEAR-Z TORSION MOM-Y MOM-Z 1 1 1 -30.23 0.26 0.00 0.00 0.00 0.00 2 30.23 -0.26 0.00 0.00 0.00 894.16 2 1 106.67 -0.08 0.00 0.00 0.00 0.00 2 -106.67 0.08 0.00 0.00 0.00 -294.48 3 1 -0.00 0.05 0.00 0.00 0.00 -0.00 2 0.00 -0.05 0.00 0.00 0.00 158.18 2 1 2 -0.25 0.21 0.00 0.00 0.00 200.03 3 0.25 -0.21 0.00 0.00 0.00 545.92 2 2 29.82 -0.44 0.00 0.00 0.00 -770.68 3 -29.82 0.44 0.00 0.00 0.00 -756.76 3 2 -0.00 -0.05 0.00 0.00 0.00 -137.99 3 0.00 0.05 0.00 0.00 0.00 -43.08 3 1 3 44.79 -0.25 0.00 0.00 0.00 -545.92 4 -44.79 0.25 0.00 0.00 0.00 -756.76 2 3 44.79 0.25 0.00 0.00 0.00 756.76 4 -44.79 -0.25 0.00 0.00 0.00 545.92 3 3 45.05 -0.00 0.00 0.00 0.00 43.08 4 -45.05 0.00 0.00 0.00 0.00 -43.08 4 1 4 29.82 0.44 0.00 0.00 0.00 756.76 5 -29.82 -0.44 0.00 0.00 0.00 770.68 2 4 -0.25 -0.21 0.00 0.00 0.00 -545.92 5 0.25 0.21 0.00 0.00 0.00 -200.03 3 4 0.00 0.05 0.00 0.00 0.00 43.08 5 -0.00 -0.05 0.00 0.00 0.00 137.99 5 1 5 106.67 0.08 0.00 0.00 0.00 294.48 6 -106.67 -0.08 0.00 0.00 0.00 0.00 2 5 -30.23 -0.26 0.00 0.00 0.00 -894.16 6 30.23 0.26 0.00 0.00 0.00 0.00 3 5 0.00 -0.05 0.00 0.00 0.00 -158.18 6 -0.00 0.05 0.00 0.00 0.00 0.00 6 1 1 -137.80 0.00 0.00 0.00 0.00 0.00 5 137.80 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 -- KNS MMS (LOCAL ) MEMBER LOAD JT AXIAL SHEAR-Y SHEAR-Z TORSION MOM-Y MOM-Z 2 2 -137.80 0.00 0.00 0.00 0.00 0.00 6 137.80 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 -53.30 0.00 0.00 0.00 0.00 0.00 4 53.30 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 -53.30 0.00 0.00 0.00 0.00 0.00 5 53.30 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 2 114.31 -0.41 0.00 0.00 0.00 -1094.19 5 -114.31 0.41 0.00 0.00 0.00 -1065.16 2 2 114.31 0.41 0.00 0.00 0.00 1065.16 5 -114.31 -0.41 0.00 0.00 0.00 1094.19 3 2 69.90 -0.00 0.00 0.00 0.00 -20.19 5 -69.90 0.00 0.00 0.00 0.00 20.19 ************** END OF LATEST ANALYSIS RESULT ************** 49. FINI EXAMPLE FOR TENSION-ONLY MEMBERS -- PAGE NO. 8 *********** END OF THE STAAD.Pro RUN *********** **** DATE= OCT 27,2022 TIME= 15: 7:41 **** ************************************************************ * 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 * ************************************************************