EX. US-3 Soil Springs for Portal Frame
A portal frame type steel structure is sitting on concrete footings. The soil is to be considered as an elastic foundation. The value of soil subgrade reaction is known from which spring constants are calculated by multiplying the subgrade reaction by the tributary area of each modeled spring.
This problem is installed with the program by default to C:\Users\Public\Public Documents\STAAD.Pro CONNECT Edition\Samples\Sample Models\US\US-3 Soil Springs for Portal Frame.STD when you install the program.
Example Problem No. 3
Where:
- B = 20 ft, H = 10 ft, F1 = 4 ft, F2 = 8 ft
- P = 5 kips, w = 3 kips/ft
- Soil Subgrade Reaction = 250 kips/ft3
Springs of Joints | Spring Constant |
---|---|
1, 5, 10, & 14 (Edges) |
8 x 1 x 250 = 2,000 kips/ft |
2, 3, 4, 11, 12, & 13 (Interior) |
8 x 2 x 250 = 4,000 kips/ft |
Actual input is shown in bold lettering followed by explanation.
STAAD PLANE PORTAL ON FOOTING FOUNDATION
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 KIPS
Defines the input units for the data that follows.
JOINT COORDINATES 1 0.0 0.0 0.0 5 8.0 0.0 0.0 6 4.0 10.0 0.0 ; 7 4.0 20.0 0.0 8 24.0 20.0 0.0 ; 9 24.0 10.0 0.0 10 20.0 0.0 0.0 14 28.0 0.0 0.0
Joint number followed by X, Y and Z coordinates are provided above. Since this is a plane structure, the Z coordinates are given as all zeros.
MEMBER INCIDENCES 1 1 2 4 5 3 6 ; 6 6 7 7 7 8 ; 8 6 9 9 8 9 ; 10 9 12 11 10 11 14
Defines the members by the joints to which they are connected.
MEMBER PROPERTIES AMERICAN 1 4 11 14 PRIS YD 1.0 ZD 8.0 2 3 12 13 PRIS YD 2.0 ZD 8.0 5 6 9 10 TA ST W10X33 7 8 TA ST W12X26
The first two lines define member properties as prismatic (PRIS) followed by depth (YD) and width (ZD) values. The program will calculate the properties necessary to perform the analysis. See G.6.1 Prismatic Properties for additional information. Member properties for the remaining members are chosen from the British steel table. The term ST stands for standard single section.
* E FOR STEEL IS 29,000 AND FOR CONCRETE 3000 UNIT INCHES DEFINE MATERIAL START ISOTROPIC STEEL E 29000 POISSON 0.3 DENSITY 0.283e-003 ALPHA 6e-006 DAMP 0.03 TYPE STEEL STRENGTH FY 36 FU 58 RY 1.5 RT 1.2 ISOTROPIC CONCRETE E 3000 POISSON 0.17 DENSITY 8.68e-005 ALPHA 5e-006 DAMP 0.05 G 1346.15 TYPE CONCRETE STRENGTH FCU 4 END DEFINE MATERIAL CONSTANTS MATERIAL STEEL MEMB 5 TO 10 MATERIAL CONCRETE MEMB 1 TO 4 11 TO 14
The CONSTANT command initiates input for material constants like modulus of elasticity, Density, and Poisson's ratio. The length unit is changed from FT to INCH to facilitate the input in familiar units.
UNIT FT SUPPORTS 2 TO 4 11 TO 13 FIXED BUT MZ KFY 4000. 1 5 10 14 FIXED BUT MZ KFY 2000.
The supports for the structure are specified above. The first set of joints are supports restrained in all directions except global moment-z (MZ). Also, a spring having a spring constant of 4,000 kip/ft is provided in the global Y direction at these nodes. The second set is similar to the former except for a different value of the spring constant.
LOADING 1 DEAD AND WIND LOAD COMBINED
Load case 1 is initiated followed by a title.
SELF Y -1.0
The selfweight of the structure is specified as acting in the global Y direction with a -1.0 factor.
Since global Y is vertically upwards, the -1.0 factor indicates that this load will act downwards.
JOINT LOAD 6 7 FX 5.0
Load 1 contains joint loads also. FX indicates that the load is a force in the global X direction.
MEMBER LOAD 7 8 UNI GY -3.0
Load 1 contains member loads also. GY indicates that the load acts in the global Y direction. The term UNI stands for uniformly distributed load, and is applied on members 7 and 8, acting downwards.
PERFORM ANALYSIS
This command instructs the program to proceed with the analysis.
PRINT ANALYSIS RESULTS
The above PRINT command instructs the program to print analysis results which include joint displacements, member forces and support reactions.
FINISH
This command terminates the STAAD run.
Input File
STAAD PLANE PORTAL ON FOOTING FOUNDATION
UNIT FT KIPS
JOINT COORDINATES
1 0.0 0.0 0.0 5 8.0 0.0 0.0
6 4.0 10.0 0.0 ; 7 4.0 20.0 0.0
8 24.0 20.0 0.0 ; 9 24.0 10.0 0.0
10 20.0 0.0 0.0 14 28.0 0.0 0.0
MEMBER INCIDENCES
1 1 2 4
5 3 6 ; 6 6 7
7 7 8 ; 8 6 9
9 8 9 ;10 9 12
11 10 11 14
MEMBER PROPERTIES AMERICAN
1 4 11 14 PRIS YD 1.0 ZD 8.0
2 3 12 13 PRIS YD 2.0 ZD 8.0
5 6 9 10 TA ST W10X33
7 8 TA ST W12X26
* E FOR STEEL IS 29,000 AND FOR CONCRETE 3000
UNIT INCHES
DEFINE MATERIAL START
ISOTROPIC STEEL
E 29000
POISSON 0.3
DENSITY 0.283e-003
ALPHA 6e-006
DAMP 0.03
TYPE STEEL
STRENGTH FY 36 FU 58 RY 1.5 RT 1.2
ISOTROPIC CONCRETE
E 3000
POISSON 0.17
DENSITY 8.68e-005
ALPHA 5e-006
DAMP 0.05
G 1346.15
TYPE CONCRETE
STRENGTH FCU 4
END DEFINE MATERIAL
CONSTANTS
MATERIAL STEEL MEMB 5 TO 10
MATERIAL CONCRETE MEMB 1 TO 4 11 TO 14
UNIT FT
SUPPORTS
2 TO 4 11 TO 13 FIXED BUT MZ KFY 4000.
1 5 10 14 FIXED BUT MZ KFY 2000.
LOADING 1 DEAD AND WIND LOAD COMBINED
SELF Y -1.0
JOINT LOAD
6 7 FX 5.0
MEMBER LOAD
7 8 UNI GY -3.0
PERFORM ANALYSIS
PRINT ANALYSIS RESULTS
FINISH
STAAD Output File
PAGE NO. 1 **************************************************** * * * STAAD.Pro CONNECT Edition * * Version 22.07.00.*** * * Proprietary Program of * * Bentley Systems, Inc. * * Date= JUL 6, 2021 * * Time= 23:32: 4 * * * * Licensed to: Bentley Systems Inc * **************************************************** 1. STAAD PLANE PORTAL ON FOOTING FOUNDATION INPUT FILE: US-3 Soil Springs for Portal Frame.STD 2. UNIT FT KIPS 3. JOINT COORDINATES 4. 1 0.0 0.0 0.0 5 8.0 0.0 0.0 5. 6 4.0 10.0 0.0 ; 7 4.0 20.0 0.0 6. 8 24.0 20.0 0.0 ; 9 24.0 10.0 0.0 7. 10 20.0 0.0 0.0 14 28.0 0.0 0.0 8. MEMBER INCIDENCES 9. 1 1 2 4 10. 5 3 6 ; 6 6 7 11. 7 7 8 ; 8 6 9 12. 9 8 9 ;10 9 12 13. 11 10 11 14 14. MEMBER PROPERTIES AMERICAN 15. 1 4 11 14 PRIS YD 1.0 ZD 8.0 16. 2 3 12 13 PRIS YD 2.0 ZD 8.0 17. 5 6 9 10 TA ST W10X33 18. 7 8 TA ST W12X26 19. * E FOR STEEL IS 29,000 AND FOR CONCRETE 3000 20. UNIT INCHES 21. DEFINE MATERIAL START 22. ISOTROPIC STEEL 23. E 29000 24. POISSON 0.3 25. DENSITY 0.283E-003 26. ALPHA 6E-006 27. DAMP 0.03 28. TYPE STEEL 29. STRENGTH FY 36 FU 58 RY 1.5 RT 1.2 30. ISOTROPIC CONCRETE 31. E 3000 32. POISSON 0.17 33. DENSITY 8.68E-005 34. ALPHA 5E-006 35. DAMP 0.05 36. G 1346.15 37. TYPE CONCRETE 38. STRENGTH FCU 4 PORTAL ON FOOTING FOUNDATION -- PAGE NO. 2 39. END DEFINE MATERIAL 40. CONSTANTS 41. MATERIAL STEEL MEMB 5 TO 10 42. MATERIAL CONCRETE MEMB 1 TO 4 11 TO 14 43. UNIT FT 44. SUPPORTS 45. 2 TO 4 11 TO 13 FIXED BUT MZ KFY 4000. 46. 1 5 10 14 FIXED BUT MZ KFY 2000. 47. LOADING 1 DEAD AND WIND LOAD COMBINED 48. SELF Y -1.0 49. JOINT LOAD 50. 6 7 FX 5.0 51. MEMBER LOAD 52. 7 8 UNI GY -3.0 53. PERFORM ANALYSIS P R O B L E M S T A T I S T I C S ----------------------------------- NUMBER OF JOINTS 14 NUMBER OF MEMBERS 14 NUMBER OF PLATES 0 NUMBER OF SOLIDS 0 NUMBER OF SURFACES 0 NUMBER OF SUPPORTS 10 Using 64-bit analysis engine. SOLVER USED IS THE IN-CORE ADVANCED MATH SOLVER TOTAL PRIMARY LOAD CASES = 1, TOTAL DEGREES OF FREEDOM = 32 TOTAL LOAD COMBINATION CASES = 0 SO FAR. 54. PRINT ANALYSIS RESULTS ANALYSIS RESULTS PORTAL ON FOOTING FOUNDATION -- 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 -0.04256 0.00000 0.00000 0.00000 -0.00028 2 1 0.00000 -0.04892 0.00000 0.00000 0.00000 -0.00023 3 1 0.00000 -0.05439 0.00000 0.00000 0.00000 -0.00020 4 1 0.00000 -0.05854 0.00000 0.00000 0.00000 -0.00017 5 1 0.00000 -0.06134 0.00000 0.00000 0.00000 -0.00010 6 1 0.32187 -0.07856 0.00000 0.00000 0.00000 -0.00483 7 1 0.64023 -0.09085 0.00000 0.00000 0.00000 -0.00669 8 1 0.62253 -0.10247 0.00000 0.00000 0.00000 0.00393 9 1 0.32940 -0.08883 0.00000 0.00000 0.00000 0.00014 10 1 0.00000 -0.03597 0.00000 0.00000 0.00000 -0.00055 11 1 0.00000 -0.04884 0.00000 0.00000 0.00000 -0.00051 12 1 0.00000 -0.06099 0.00000 0.00000 0.00000 -0.00049 13 1 0.00000 -0.07163 0.00000 0.00000 0.00000 -0.00043 14 1 0.00000 -0.08045 0.00000 0.00000 0.00000 -0.00035 PORTAL ON FOOTING FOUNDATION -- PAGE NO. 4 SUPPORT REACTIONS -UNIT KIPS FEET STRUCTURE TYPE = PLANE ----------------- JOINT LOAD FORCE-X FORCE-Y FORCE-Z MOM-X MOM-Y MOM Z 2 1 0.00 16.31 0.00 0.00 0.00 0.00 3 1 -0.60 18.13 0.00 0.00 0.00 0.00 4 1 0.00 19.51 0.00 0.00 0.00 0.00 11 1 0.00 16.28 0.00 0.00 0.00 0.00 12 1 -9.40 20.33 0.00 0.00 0.00 0.00 13 1 0.00 23.88 0.00 0.00 0.00 0.00 1 1 0.00 7.09 0.00 0.00 0.00 0.00 5 1 0.00 10.22 0.00 0.00 0.00 0.00 10 1 0.00 5.99 0.00 0.00 0.00 0.00 14 1 0.00 13.41 0.00 0.00 0.00 0.00 PORTAL ON FOOTING FOUNDATION -- PAGE NO. 5 MEMBER END FORCES STRUCTURE TYPE = PLANE ----------------- ALL UNITS ARE -- KIPS FEET (LOCAL ) MEMBER LOAD JT AXIAL SHEAR-Y SHEAR-Z TORSION MOM-Y MOM-Z 1 1 1 0.00 7.09 0.00 0.00 0.00 0.00 2 0.00 -4.69 0.00 0.00 0.00 11.79 2 1 2 0.00 21.00 0.00 0.00 0.00 -11.79 3 0.00 -16.20 0.00 0.00 0.00 48.99 3 1 3 0.00 -22.54 0.00 0.00 0.00 -67.92 4 0.00 27.34 0.00 0.00 0.00 18.05 4 1 4 0.00 -7.82 0.00 0.00 0.00 -18.05 5 0.00 10.22 0.00 0.00 0.00 0.00 5 1 3 56.87 0.60 0.00 0.00 0.00 18.93 6 -56.54 -0.60 0.00 0.00 0.00 -12.95 6 1 6 29.01 -11.36 0.00 0.00 0.00 -50.40 7 -28.68 11.36 0.00 0.00 0.00 -63.23 7 1 7 16.36 28.68 0.00 0.00 0.00 63.23 8 -16.36 31.84 0.00 0.00 0.00 -94.86 8 1 6 -6.96 27.53 0.00 0.00 0.00 63.35 9 6.96 32.99 0.00 0.00 0.00 -117.94 9 1 8 31.84 16.36 0.00 0.00 0.00 94.86 9 -32.17 -16.36 0.00 0.00 0.00 68.77 10 1 9 65.16 9.40 0.00 0.00 0.00 49.17 12 -65.49 -9.40 0.00 0.00 0.00 44.85 11 1 10 0.00 5.99 0.00 0.00 0.00 0.00 11 0.00 -3.59 0.00 0.00 0.00 9.59 12 1 11 0.00 19.87 0.00 0.00 0.00 -9.59 12 0.00 -15.07 0.00 0.00 0.00 44.54 13 1 12 0.00 -30.08 0.00 0.00 0.00 -89.39 13 0.00 34.88 0.00 0.00 0.00 24.42 14 1 13 0.00 -11.01 0.00 0.00 0.00 -24.42 14 0.00 13.41 0.00 0.00 0.00 0.00 PORTAL ON FOOTING FOUNDATION -- PAGE NO. 6 ************** END OF LATEST ANALYSIS RESULT ************** 55. FINISH *********** END OF THE STAAD.Pro RUN *********** **** DATE= JUL 6,2021 TIME= 23:32: 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 * ************************************************************