EX. US-7 Modeling Offset Connections in a Frame
This example illustrates modeling of structures with offset connections. Offset connections arise when the center lines of the connected members do not intersect at the connection point. The connection eccentricity behaves as a rigid link and is modeled through specification of MEMBER OFFSETS.
This problem is installed with the program by default to C:\Users\Public\Public Documents\STAAD.Pro CONNECT Edition\Samples\Sample Models\US\US-7 Modeling Offset Connections in a Frame.STD when you install the program.
- L1 = 15 ft
- L2 = 20 ft
- L3 = 7 in
- L4 = 6 in
Actual input is shown in bold lettering followed by explanation.
STAAD PLANE TEST FOR MEMBER OFFSETS
Every input has to start with the term STAAD. The term PLANE signifies that the structure is a plane frame structure and the geometry is defined through X and Y axes.
UNIT FT KIP
Defines the input units for the data that follows.
JOINT COORD 1 0. 0. ; 2 20. 0. ; 3 0. 15. 4 20. 15. ; 5 0. 30. ; 6 20. 30.
Joint number followed by X and Y coordinates are provided above. Since this is a plane structure, the Z coordinates need not be provided.
SUPPORT 1 2 PINNED
Pinned supports are specified at joints 1 and 2. The word PINNED signifies that no moments will be carried by these supports.
MEMB INCI 1 1 3 2 ; 3 3 5 4 5 3 4 ; 6 5 6 ; 7 1 4
Defines the members by the joints to which they are connected.
MEMB PROP AMERICAN 1 TO 4 TABLE ST W14X90 5 6 TA ST W12X26 7 TA LD L80608
Member properties are assigned from the American (AISC) steel table for all members. The word ST stands for standard single section. LD stands for long leg back-to-back double angle.
UNIT INCH MEMB OFFSET 5 6 START 7.0 0.0 0.0 5 6 END -7.0 0.0 0.0 7 END -7.0 -6.0 0.0
The preceding specification states that an OFFSET is located at the START/END joint of the members. The X, Y, and Z global coordinates of the offset distance from the corresponding incident joint are also provided. These attributes are applied to members 5, 6, and 7.
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.
LOADING 1 WIND LOAD
Load case 1 is initiated followed by a title.
JOINT LOAD 3 FX 50. ; 5 FX 25.0
Load 1 contains joint loads at nodes 3 and 5. FX indicates that the load is a force in the global X direction.
PERFORM ANALYSIS
The above command is an instruction to perform the analysis.
UNIT FT PRINT FORCES PRINT REACTIONS
The above PRINT commands are instructions for writing the member forces and support reactions to the output file. The preceding line causes the results to be written in the length unit of feet.
FINISH
This command terminates a STAAD run.
Input File
STAAD PLANE TEST FOR MEMBER OFFSETS
UNIT FT KIP
JOINT COORD
1 0. 0. ; 2 20. 0. ; 3 0. 15.
4 20. 15. ; 5 0. 30. ; 6 20. 30.
MEMB INCI
1 1 3 2; 3 3 5 4
5 3 4 ; 6 5 6 ; 7 1 4
MEMB PROP AMERICAN
1 TO 4 TABLE ST W14X90
5 6 TA ST W12X26
7 TA LD L80608
UNIT INCH
MEMB OFFSET
5 6 START 7.0 0.0 0.0
5 6 END -7.0 0.0 0.0
7 END -7.0 -6.0 0.0
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
SUPPORT
1 2 PINNED
LOADING 1 WIND LOAD
JOINT LOAD
3 FX 50. ; 5 FX 25.0
PERFORM ANALYSIS
UNIT FT
PRINT FORCES
PRINT REACTIONS
FINISH
STAAD Output File
PAGE NO. 1 **************************************************** * * * STAAD.Pro CONNECT Edition * * Version 22.07.00.** * * Proprietary Program of * * Bentley Systems, Inc. * * Date= APR 19, 2021 * * Time= 17:28:46 * * * * Licensed to: Bentley Systems Inc * **************************************************** 1. STAAD PLANE TEST FOR MEMBER OFFSETS INPUT FILE: US-7 Modeling Offset Connections in a Frame.STD 2. UNIT FT KIP 3. JOINT COORD 4. 1 0. 0. ; 2 20. 0. ; 3 0. 15. 5. 4 20. 15. ; 5 0. 30. ; 6 20. 30. 6. MEMB INCI 7. 1 1 3 2; 3 3 5 4 8. 5 3 4 ; 6 5 6 ; 7 1 4 9. MEMB PROP AMERICAN 10. 1 TO 4 TABLE ST W14X90 11. 5 6 TA ST W12X26 12. 7 TA LD L80608 13. UNIT INCH 14. MEMB OFFSET 15. 5 6 START 7.0 0.0 0.0 16. 5 6 END -7.0 0.0 0.0 17. 7 END -7.0 -6.0 0.0 18. DEFINE MATERIAL START 19. ISOTROPIC STEEL 20. E 29000 21. POISSON 0.3 22. DENSITY 283E-006 23. ALPHA 6E-006 24. DAMP 0.03 25. TYPE STEEL 26. STRENGTH FY 36 FU 58 RY 1.5 RT 1.2 27. END DEFINE MATERIAL 28. CONSTANT 29. MATERIAL STEEL ALL 30. SUPPORT 31. 1 2 PINNED 32. LOADING 1 WIND LOAD 33. JOINT LOAD 34. 3 FX 50. ; 5 FX 25.0 35. PERFORM ANALYSIS TEST FOR MEMBER OFFSETS -- 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 7 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. 36. UNIT FT 37. PRINT FORCES FORCES TEST FOR MEMBER OFFSETS -- PAGE NO. 3 MEMBER END FORCES STRUCTURE TYPE = PLANE ----------------- ALL UNITS ARE -- KIP FEET (LOCAL ) MEMBER LOAD JT AXIAL SHEAR-Y SHEAR-Z TORSION MOM-Y MOM-Z 1 1 1 -10.69 -4.61 0.00 0.00 0.00 3.56 3 10.69 4.61 0.00 0.00 0.00 -72.68 2 1 2 75.00 -5.73 0.00 0.00 0.00 0.00 4 -75.00 5.73 0.00 0.00 0.00 -85.95 3 1 3 -6.73 11.92 0.00 0.00 0.00 112.47 5 6.73 -11.92 0.00 0.00 0.00 66.37 4 1 4 6.73 13.08 0.00 0.00 0.00 127.91 6 -6.73 -13.08 0.00 0.00 0.00 68.25 5 1 3 66.53 -3.96 0.00 0.00 0.00 -37.49 4 -66.53 3.96 0.00 0.00 0.00 -37.16 6 1 5 13.08 -6.73 0.00 0.00 0.00 -62.44 6 -13.08 6.73 0.00 0.00 0.00 -64.32 7 1 1 -106.85 -0.46 0.00 0.00 0.00 -3.56 4 106.85 0.46 0.00 0.00 0.00 -7.64 ************** END OF LATEST ANALYSIS RESULT ************** 38. PRINT REACTIONS REACTION TEST FOR MEMBER OFFSETS -- PAGE NO. 4 SUPPORT REACTIONS -UNIT KIP FEET STRUCTURE TYPE = PLANE ----------------- JOINT LOAD FORCE-X FORCE-Y FORCE-Z MOM-X MOM-Y MOM Z 1 1 -80.73 -75.00 0.00 0.00 0.00 0.00 2 1 5.73 75.00 0.00 0.00 0.00 0.00 ************** END OF LATEST ANALYSIS RESULT ************** 39. FINISH *********** END OF THE STAAD.Pro RUN *********** **** DATE= APR 19,2021 TIME= 17:28:47 **** TEST FOR MEMBER OFFSETS -- PAGE NO. 5 ************************************************************ * 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 * ************************************************************