EX. US-6 Prestress and Poststress Loading
This is an example of prestress loading in a plane frame structure.
- From the member on which it is applied, the prestressing effect is transmitted to the rest of the structure through the connecting members (known in the program as PRESTRESS load).
- The prestressing effect is experienced by the member(s) alone and not transmitted to the rest of the structure (known in the program as POSTSTRESS load).
This problem is installed with the program by default to C:\Users\Public\Public Documents\STAAD.Pro CONNECT Edition\Samples\Sample Models\US\US-6 Prestress and Poststress Loading.STD when you install the program.
- L1 = 15 ft
- L2 = 20 ft
- L3 = 40 ft
Actual input is shown in bold lettering followed by explanation.
STAAD PLANE FRAME WITH PRESTRESSING LOAD
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 KIP FT
Defines the input units for the data that follows.
JOINT COORD
1 0. 0. ; 2 40. 0. ; 3 0. 20. ; 4 40. 20.
5 0. 35. ; 6 40. 35. ; 7 0. 50. ; 8 40. 50.
Joint number followed by X and Y coordinates are provided above. Since this is a plane structure, the Z coordinates need not be provided.
MEMBER INCIDENCE
1 1 3 ; 2 3 5 ; 3 5 7 ; 4 2 4 ; 5 4 6
6 6 8 ; 7 3 4 ; 8 5 6 ; 9 7 8
Defines the members by the joints to which they are connected.
SUPPORT
1 2 FIXED
The supports at joints 1 and 2 are defined to be fixed supports.
MEMB PROP
1 TO 9 PRI AX 2.2 IZ 1.0
Member properties are provided using the PRI (prismatic) attribute. Values of area (AX) and moment of inertia about the major axis (IZ) are provided.
UNIT INCH
DEFINE MATERIAL START
ISOTROPIC CONCRETE
E 3000.
POISSON 0.17
DENSITY 8.7e-005
ALPHA 5e-006
DAMP 0.05
G 1346.15
TYPE CONCRETE
STRENGTH FCU 4
END DEFINE MATERIAL
CONSTANTS
MATERIAL CONCRETE ALL
The DEFINE MATERIAL command is used to specify material properities and the CONSTANT command is used to assign the material to all members. Length unit is changed from FT to INCH to facilitate the input.
LOADING 1 PRESTRESSING LOAD
MEMBER PRESTRESS
7 8 FORCE 300. ES 3. EM -12. EE 3.
Load case 1 is initiated along with an accompanying title. Load 1 contains PRESTRESS load. Members 7 and 8 have a cable force of 300 kips. The location of the cable at the start (ES) and end (EE) is 3 inches above the center of gravity while at the middle (EM) it is 12 inches below the c.g. The assumptions and facts associated with this type of loading are explained in G.15.5 Prestress and Poststress Member Load.
LOADING 2 POSTSTRESSING LOAD
MEMBER POSTSTRESS
7 8 FORCE 300. ES 3. EM -12. EE 3.
Load case 2 is initiated along with an accompanying title. Load 2 is a POSTSTRESS load. Members 7 and 8 have cable force of 300 kips. The location of the cable is the same as in load case 1. For a difference between PRESTRESS loading and POSTSTRESS loading, as well as additional information about both types of loads, please refer to G.15.5 Prestress and Poststress Member Load.
PERFORM ANALYSIS
This command instructs the program to perform the analysis.
UNIT FT
PRINT ANALYSIS RESULT
The preceding command is an instruction to write joint displacements, support reactions and member forces in the output file. The preceding line causes the results to be written in the length unit of feet.
FINISH
This command terminates the STAAD run.
Input File
STAAD PLANE FRAME WITH PRESTRESSING LOAD
UNIT KIP FT
JOINT COORD
1 0. 0. ; 2 40. 0. ; 3 0. 20. ; 4 40. 20.
5 0. 35. ; 6 40. 35. ; 7 0. 50. ; 8 40. 50.
MEMBER INCIDENCE
1 1 3 ; 2 3 5 ; 3 5 7 ; 4 2 4 ; 5 4 6
6 6 8 ; 7 3 4 ; 8 5 6 ; 9 7 8
SUPPORT
1 2 FIXED
MEMB PROP
1 TO 9 PRI AX 2.2 IZ 1.0
UNIT INCH
DEFINE MATERIAL START
ISOTROPIC CONCRETE
E 3000.
POISSON 0.17
DENSITY 8.7e-005
ALPHA 5e-006
DAMP 0.05
G 1346.15
TYPE CONCRETE
STRENGTH FCU 4
END DEFINE MATERIAL
CONSTANTS
MATERIAL CONCRETE ALL
LOADING 1 PRESTRESSING LOAD
MEMBER PRESTRESS
7 8 FORCE 300. ES 3. EM -12. EE 3.
LOADING 2 POSTSTRESSING LOAD
MEMBER POSTSTRESS
7 8 FORCE 300. ES 3. EM -12. EE 3.
PERFORM ANALYSIS
UNIT FT
PRINT ANALYSIS RESULT
FINISH
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= 15:10:20 * * * * Licensed to: Bentley Systems Inc * **************************************************** 1. STAAD PLANE FRAME WITH PRESTRESSING LOAD INPUT FILE: US-6 Prestress and Poststress Loading.STD 2. UNIT KIP FT 3. JOINT COORD 4. 1 0. 0. ; 2 40. 0. ; 3 0. 20. ; 4 40. 20. 5. 5 0. 35. ; 6 40. 35. ; 7 0. 50. ; 8 40. 50. 6. MEMBER INCIDENCE 7. 1 1 3 ; 2 3 5 ; 3 5 7 ; 4 2 4 ; 5 4 6 8. 6 6 8 ; 7 3 4 ; 8 5 6 ; 9 7 8 9. SUPPORT 10. 1 2 FIXED 11. MEMB PROP 12. 1 TO 9 PRI AX 2.2 IZ 1.0 13. UNIT INCH 14. DEFINE MATERIAL START 15. ISOTROPIC CONCRETE 16. E 3000. 17. POISSON 0.17 18. DENSITY 8.7E-005 19. ALPHA 5E-006 20. DAMP 0.05 21. G 1346.15 22. TYPE CONCRETE 23. STRENGTH FCU 4 24. END DEFINE MATERIAL 25. CONSTANTS 26. MATERIAL CONCRETE ALL 27. LOADING 1 PRESTRESSING LOAD 28. MEMBER PRESTRESS 29. 7 8 FORCE 300. ES 3. EM -12. EE 3. 30. LOADING 2 POSTSTRESSING LOAD 31. MEMBER POSTSTRESS 32. 7 8 FORCE 300. ES 3. EM -12. EE 3. 33. PERFORM ANALYSIS FRAME WITH PRESTRESSING LOAD -- PAGE NO. 2 P R O B L E M S T A T I S T I C S ----------------------------------- NUMBER OF JOINTS 8 NUMBER OF MEMBERS 9 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 = 2, TOTAL DEGREES OF FREEDOM = 18 TOTAL LOAD COMBINATION CASES = 0 SO FAR. 34. UNIT FT 35. PRINT ANALYSIS RESULT ANALYSIS RESULT FRAME WITH PRESTRESSING LOAD -- PAGE NO. 3 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 0.00000 2 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 2 1 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 2 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 3 1 0.07698 0.00000 0.00000 0.00000 0.00000 0.00039 2 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 4 1 -0.07698 0.00000 0.00000 0.00000 0.00000 -0.00039 2 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 5 1 0.07224 0.00000 0.00000 0.00000 0.00000 0.00087 2 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 6 1 -0.07224 0.00000 0.00000 0.00000 0.00000 -0.00087 2 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 7 1 -0.00059 0.00000 0.00000 0.00000 0.00000 0.00015 2 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 8 1 0.00059 0.00000 0.00000 0.00000 0.00000 -0.00015 2 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 FRAME WITH PRESTRESSING LOAD -- 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 -6.71 0.00 0.00 0.00 0.00 58.62 2 0.00 0.00 0.00 0.00 0.00 0.00 2 1 6.71 0.00 0.00 0.00 0.00 -58.62 2 0.00 0.00 0.00 0.00 0.00 0.00 FRAME WITH PRESTRESSING LOAD -- PAGE NO. 5 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 0.00 6.71 0.00 0.00 0.00 58.62 3 -0.00 -6.71 0.00 0.00 0.00 75.67 2 1 0.00 0.00 0.00 0.00 0.00 0.00 3 0.00 0.00 0.00 0.00 0.00 0.00 2 1 3 0.00 13.92 0.00 0.00 0.00 90.81 5 -0.00 -13.92 0.00 0.00 0.00 117.98 2 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 3 1 5 0.00 2.34 0.00 0.00 0.00 38.31 7 -0.00 -2.34 0.00 0.00 0.00 -3.16 2 5 0.00 0.00 0.00 0.00 0.00 0.00 7 0.00 0.00 0.00 0.00 0.00 0.00 4 1 2 -0.00 -6.71 0.00 0.00 0.00 -58.62 4 0.00 6.71 0.00 0.00 0.00 -75.67 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 5 1 4 -0.00 -13.92 0.00 0.00 0.00 -90.81 6 0.00 13.92 0.00 0.00 0.00 -117.98 2 4 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 6 1 6 -0.00 -2.34 0.00 0.00 0.00 -38.31 8 0.00 2.34 0.00 0.00 0.00 3.16 2 6 0.00 0.00 0.00 0.00 0.00 0.00 8 0.00 0.00 0.00 0.00 0.00 0.00 7 1 3 304.85 -37.50 0.00 0.00 0.00 -241.48 4 -304.85 -37.50 0.00 0.00 0.00 241.48 2 3 297.65 -37.50 0.00 0.00 0.00 -75.00 4 -297.65 -37.50 0.00 0.00 0.00 75.00 8 1 5 286.07 -37.50 0.00 0.00 0.00 -231.29 6 -286.07 -37.50 0.00 0.00 0.00 231.29 2 5 297.65 -37.50 0.00 0.00 0.00 -75.00 6 -297.65 -37.50 0.00 0.00 0.00 75.00 9 1 7 -2.34 0.00 0.00 0.00 0.00 3.16 8 2.34 -0.00 0.00 0.00 0.00 -3.16 FRAME WITH PRESTRESSING LOAD -- PAGE NO. 6 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 2 7 0.00 0.00 0.00 0.00 0.00 0.00 8 0.00 0.00 0.00 0.00 0.00 0.00 ************** END OF LATEST ANALYSIS RESULT ************** 36. FINISH *********** END OF THE STAAD.Pro RUN *********** **** DATE= OCT 27,2022 TIME= 15:10:21 **** FRAME WITH PRESTRESSING LOAD -- PAGE NO. 7 ************************************************************ * 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 * ************************************************************