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EX. US-9 Modeling Slabs and Shear Walls Using Finite Elements

The space frame structure in this example consists of frame members and finite elements (plates). The finite element part is used to model floor slabs and a shear wall. Concrete design of an element is performed.

This problem is installed with the program by default to C:\Users\Public\Public Documents\STAAD.Pro CONNECT Edition\Samples\Sample Models\US\US-9 Modeling Slabs and Shear Walls Using Finite Elements.STD when you install the program.

Example Problem No. 9

Actual input is shown in bold lettering followed by explanation.

    STAAD SPACE 
    * EXAMPLE PROBLEM WITH FRAME MEMBERS AND FINITE ELEMENTS

Every STAAD input file has to begin with the word STAAD. The word SPACE signifies that the structure is a space frame and the geometry is defined through X, Y and Z axes. The second line forms the title to identify this project.

    UNIT FEET KIP

The units for the data that follows are specified above.

    JOINT COORD
    1 0 0 0 ; 2 0 0 20
    REP ALL 2 20 0 0
    7 0 15 0 11 0 15 20
    12 5 15 0 14 15 15 0
    15 5 15 20 17 15 15 20
    18 20 15 0 22 20 15 20
    23 25 15 0 25 35 15 0
    26 25 15 20 28 35 15 20
    29 40 15 0 33 40 15 20
    34 20 3.75 0 36 20 11.25 0
    37 20 3.75 20 39 20 11.25 20

The joint numbers and their coordinates are defined through the above set of commands. The automatic generation facility has been used several times in the above lines. See TR.11 Joint Coordinates Specification where the joint coordinate generation facilities are described.

    MEMBER INCI
    *COLUMNS
    1 1 7 ; 2 2 11
    3 3 34 ; 4 34 35 ; 5 35 36 ; 6 36 18
    7 4 37 ; 8 37 38 ; 9 38 39 ; 10 39 22
    11 5 29 ; 12 6 33
    *BEAMS IN Z DIRECTION AT X=0
    13 7 8 16
    *BEAMS IN Z DIRECTION AT X=20
    17 18 19 20
    *BEAMS IN Z DIRECTION AT X=40
    21 29 30 24
    *BEAMS IN X DIRECTION AT Z = 0
    25 7 12 ; 26 12 13 ; 27 13 14 ; 28 14 18
    29 18 23 ; 30 23 24 ; 31 24 25 ; 32 25 29
    *BEAMS IN X DIRECTION AT Z = 20
    33 11 15 ; 34 15 16 ; 35 16 17 ; 36 17 22
    37 22 26 ; 38 26 27 ; 39 27 28 ; 40 28 33

The member incidences are defined through the above set of commands. For some members, the member number followed by the start and end joint numbers are defined. In other cases, STAAD's automatic generation facilities are utilized. Refer to TR.12 Member Incidences Specification for additional details.

    DEFINE MESH
    A JOINT 7
    B JOINT 11
    C JOINT 22
    D JOINT 18
    E JOINT 33
    F JOINT 29
    G JOINT 3
    H JOINT 4

The above lines define the nodes of super-elements. Super-elements are plate/shell surfaces from which a number of individual plate/shell elements can be generated. In this case, the points describe the outer corners of a slab and that of a shear wall. Our goal is to define the slab and the wall as several plate/shell elements.

    GENERATE ELEMENT
    MESH ABCD 4 4
    MESH DCEF 4 4
    MESH DCHG 4 4

The above lines form the instructions to generate individual 4-noded elements from the super-element profiles. For example, the command MESH ABCD 4 4 means that STAAD.Pro has to generate 16 elements from the surface formed by the points A, B, C and D with 4 elements along the edges AB & CD and 4 elements along the edges BC & DA.

    MEMB PROP
    1 TO 40 PRIS YD 1 ZD 1

Members 1 to 40 are defined as a rectangular prismatic section with 1 ft depth and 1 ft width.

    ELEM PROP
    41 TO 88 TH 0.5

Elements 41 to 88 are defined to be 0.5 ft thick.

    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 properties and the CONSTANT is used to assign the material to all members.

    SUPPORT
    1 TO 6 FIXED

Joints 1 to 6 are defined as fixed supported.

    UNIT FEET
    LOAD 1 DEAD LOAD FROM FLOOR
    ELEMENT LOAD
    41 TO 72 PRESSURE -1.0

Load 1 consists of a pressure load of 1 Kip/sq.ft. intensity on elements 41 to 72. The negative sign (and the default value for the axis) indicates that the load acts opposite to the positive direction of the element local z-axis.

    LOAD 2 WIND LOAD
    JOINT LOAD
    11 33 FZ -20.
    22 FZ -100.

Load 2 consists of joint loads in the Z direction at joints 11, 22, and 33.

    LOAD COMB 3
    1 0.9 2 1.3

Load 3 is a combination of 0.9 times load case 1 and 1.3 times load case 2.

    PERFORM ANALYSIS

The command to perform an elastic analysis is specified above.

    LOAD LIST 1 3
    PRINT SUPP REAC
    PRINT MEMBER FORCES LIST 27
    PRINT ELEMENT STRESSES LIST 47

Support reactions, members forces and element stresses are printed for load cases 1 and 3.

    START CONCRETE DESIGN
    CODE ACI
    DESIGN ELEMENT 47
    END CONCRETE DESIGN

The above set of command form the instructions to STAAD to perform a concrete design on element 47. Design is done according to the ACI 318 code. Note that design will consist only of flexural reinforcement calculations in the longitudinal and transverse directions of the elements for the moments MX and MY.

    FINI

The STAAD run is terminated.

Input File

STAAD SPACE
* EXAMPLE PROBLEM WITH FRAME MEMBERS AND
* FINITE ELEMENTS
UNIT FEET KIP
JOINT COORD
1 0 0 0 ; 2 0 0 20
REP ALL 2 20 0 0
7 0 15 0 11 0 15 20
12 5 15 0 14 15 15 0
15 5 15 20 17 15 15 20
18 20 15 0 22 20 15 20
23 25 15 0 25 35 15 0
26 25 15 20 28 35 15 20
29 40 15 0 33 40 15 20
34 20 3.75 0 36 20 11.25 0
37 20 3.75 20 39 20 11.25 20
MEMBER INCI
*COLUMNS
1 1 7 ; 2 2 11
3 3 34 ; 4 34 35 ; 5 35 36 ; 6 36 18
7 4 37 ; 8 37 38 ; 9 38 39 ; 10 39 22
11 5 29 ; 12 6 33
*BEAMS IN Z DIRECTION AT X=0
13 7 8 16
*BEAMS IN Z DIRECTION AT X=20
17 18 19 20
*BEAMS IN Z DIRECTION AT X=40
21 29 30 24
*BEAMS IN X DIRECTION AT Z = 0
25 7 12 ; 26 12 13 ; 27 13 14 ; 28 14 18
29 18 23 ; 30 23 24 ; 31 24 25 ; 32 25 29
*BEAMS IN X DIRECTION AT Z = 20
33 11 15 ; 34 15 16 ; 35 16 17 ; 36 17 22
37 22 26 ; 38 26 27 ; 39 27 28 ; 40 28 33
DEFINE MESH
A JOINT 7
B JOINT 11
C JOINT 22
D JOINT 18
E JOINT 33
F JOINT 29
G JOINT 3
H JOINT 4
GENERATE ELEMENT
MESH ABCD 4 4
MESH DCEF 4 4
MESH DCHG 4 4
MEMB PROP
1 TO 40 PRIS YD 1 ZD 1
ELEM PROP
41 TO 88 TH 0.5
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
SUPPORT
1 TO 6 FIXED
UNIT FEET
LOAD 1 DEAD LOAD FROM FLOOR
ELEMENT LOAD
41 TO 72 PRESSURE -1.0
LOAD 2 WIND LOAD
JOINT LOAD
11 33 FZ -20.
22 FZ -100.
LOAD COMB 3
1 0.9 2 1.3
PERFORM ANALYSIS
LOAD LIST 1 3
PRINT SUPP REAC
PRINT MEMBER FORCES LIST 27
PRINT ELEMENT STRESSES LIST 47
START CONCRETE DESIGN
CODE ACI
DESIGN ELEMENT 47
END CONCRETE DESIGN
FINI

STAAD Output File

                                                                  PAGE NO.    1
             ****************************************************        
             *                                                  *        
             *           STAAD.Pro CONNECT Edition              *        
             *           Version  22.04.00.**                   *        
             *           Proprietary Program of                 *        
             *           Bentley Systems, Inc.                  *        
             *           Date=    APR 21, 2020                  *        
             *           Time=    15:42:50                      *        
             *                                                  *        
             *  Licensed to: Bentley Systems Inc                *        
             ****************************************************        
     1. STAAD SPACE
INPUT FILE: US-9 Modeling Slabs and Shear Walls Using Finite Elements.STD
     2. * EXAMPLE PROBLEM WITH FRAME MEMBERS AND
     3. * FINITE ELEMENTS
     4. UNIT FEET KIP
     5. JOINT COORD
     6. 1 0 0 0 ; 2 0 0 20
     7. REP ALL 2 20 0 0
     8. 7 0 15 0 11 0 15 20
     9. 12 5 15 0 14 15 15 0
    10. 15 5 15 20 17 15 15 20
    11. 18 20 15 0 22 20 15 20
    12. 23 25 15 0 25 35 15 0
    13. 26 25 15 20 28 35 15 20
    14. 29 40 15 0 33 40 15 20
    15. 34 20 3.75 0 36 20 11.25 0
    16. 37 20 3.75 20 39 20 11.25 20
    17. MEMBER INCI
    18. *COLUMNS
    19. 1 1 7 ; 2 2 11
    20. 3 3 34 ; 4 34 35 ; 5 35 36 ; 6 36 18
    21. 7 4 37 ; 8 37 38 ; 9 38 39 ; 10 39 22
    22. 11 5 29 ; 12 6 33
    23. *BEAMS IN Z DIRECTION AT X=0
    24. 13 7 8 16
    25. *BEAMS IN Z DIRECTION AT X=20
    26. 17 18 19 20
    27. *BEAMS IN Z DIRECTION AT X=40
    28. 21 29 30 24
    29. *BEAMS IN X DIRECTION AT Z = 0
    30. 25 7 12 ; 26 12 13 ; 27 13 14 ; 28 14 18
    31. 29 18 23 ; 30 23 24 ; 31 24 25 ; 32 25 29
    32. *BEAMS IN X DIRECTION AT Z = 20
    33. 33 11 15 ; 34 15 16 ; 35 16 17 ; 36 17 22
    34. 37 22 26 ; 38 26 27 ; 39 27 28 ; 40 28 33
    35. DEFINE MESH
    36. A JOINT 7
    37. B JOINT 11
    38. C JOINT 22
      STAAD SPACE                                              -- PAGE NO.    2
    * EXAMPLE PROBLEM WITH FRAME MEMBERS AND    
    39. D JOINT 18
    40. E JOINT 33
    41. F JOINT 29
    42. G JOINT 3
    43. H JOINT 4
    44. GENERATE ELEMENT
    45. MESH ABCD 4 4
    46. MESH DCEF 4 4
    47. MESH DCHG 4 4
    48. MEMB PROP
    49. 1 TO 40 PRIS YD 1 ZD 1
    50. ELEM PROP
    51. 41 TO 88 TH 0.5
    52. UNIT INCH
    53. DEFINE MATERIAL START
    54. ISOTROPIC CONCRETE
    55. E 3000
    56. POISSON 0.17
    57. DENSITY 8.7E-005
    58. ALPHA 5E-006
    59. DAMP 0.05
    60. G 1346.15
    61. TYPE CONCRETE
    62. STRENGTH FCU 4
    63. END DEFINE MATERIAL
    64. CONSTANTS
    65. MATERIAL CONCRETE ALL
    66. SUPPORT
    67. 1 TO 6 FIXED
    68. UNIT FEET
    69. LOAD 1 DEAD LOAD FROM FLOOR
    70. ELEMENT LOAD
    71. 41 TO 72 PRESSURE -1.0
    72. LOAD 2 WIND LOAD
    73. JOINT LOAD
    74. 11 33 FZ -20.
    75. 22 FZ -100.
    76. LOAD COMB 3
    77. 1 0.9 2 1.3
    78. PERFORM ANALYSIS
            P R O B L E M   S T A T I S T I C S
            -----------------------------------
     NUMBER OF JOINTS         69  NUMBER OF MEMBERS      40
     NUMBER OF PLATES         48  NUMBER OF SOLIDS        0
     NUMBER OF SURFACES        0  NUMBER OF SUPPORTS      6
           Using 64-bit analysis engine.
      STAAD SPACE                                              -- PAGE NO.    3
    * EXAMPLE PROBLEM WITH FRAME MEMBERS AND    
           SOLVER USED IS THE IN-CORE ADVANCED MATH SOLVER
   TOTAL      PRIMARY LOAD CASES =     2, TOTAL DEGREES OF FREEDOM =     378
   TOTAL LOAD COMBINATION  CASES =     1  SO FAR.
    79. LOAD LIST 1 3
    80. PRINT SUPP REAC
  SUPP     REAC                       
      STAAD SPACE                                              -- PAGE NO.    4
    * EXAMPLE PROBLEM WITH FRAME MEMBERS AND    
   SUPPORT REACTIONS -UNIT KIP  FEET    STRUCTURE TYPE = SPACE
   -----------------
 JOINT  LOAD   FORCE-X   FORCE-Y   FORCE-Z     MOM-X     MOM-Y     MOM Z
      1    1      9.11     82.56     11.46     56.95     -0.01    -45.28
           3      8.23     74.62     10.65     54.04      0.03    -40.81
      2    1      9.11     82.56    -11.46    -56.95      0.01    -45.28
           3      8.19     73.98     -9.97    -48.33      0.19    -40.77
      3    1      0.00    234.89     75.78    -39.25      0.00      0.00
           3      0.00    345.09    160.48    -19.17      0.00      0.00
      4    1      0.00    234.89    -75.78     39.25      0.00      0.00
           3      0.00     77.69     20.17     50.98      0.00      0.00
      5    1     -9.11     82.56     11.46     56.95      0.01     45.28
           3     -8.23     74.62     10.65     54.04     -0.03     40.81
      6    1     -9.11     82.56    -11.46    -56.95     -0.01     45.28
           3     -8.19     73.98     -9.97    -48.33     -0.19     40.77
   ************** END OF LATEST ANALYSIS RESULT **************
    81. PRINT MEMBER FORCES LIST 27
  MEMBER   FORCES   LIST     27       
      STAAD SPACE                                              -- PAGE NO.    5
    * EXAMPLE PROBLEM WITH FRAME MEMBERS AND    
   MEMBER END FORCES    STRUCTURE TYPE = SPACE
   -----------------
   ALL UNITS ARE -- KIP  FEET     (LOCAL )
  MEMBER  LOAD  JT     AXIAL   SHEAR-Y  SHEAR-Z   TORSION     MOM-Y      MOM-Z
     27    1    13      0.73    -13.21    -0.07     25.88      0.18     -80.00
                14     -0.73     13.21     0.07    -25.88      0.18      13.96
           3    13      5.42    -11.85    -0.21     23.44      0.51     -72.04
                14     -5.42     11.85     0.21    -23.44      0.53      12.79
   ************** END OF LATEST ANALYSIS RESULT **************
    82. PRINT ELEMENT STRESSES LIST 47
  ELEMENT  STRESSES LIST     47       
      STAAD SPACE                                              -- PAGE NO.    6
    * EXAMPLE PROBLEM WITH FRAME MEMBERS AND    
   ELEMENT STRESSES    FORCE,LENGTH UNITS= KIP  FEET
   ----------------
            STRESS = FORCE/UNIT WIDTH/THICK, MOMENT = FORCE-LENGTH/UNIT WIDTH
  ELEMENT  LOAD       SQX        SQY          MX          MY          MXY
                      VONT       VONB         SX          SY          SXY
                      TRESCAT    TRESCAB
     47      1         1.71        0.50      -11.52      -14.78        1.47
                     330.22      326.90       -1.21       -1.70        0.52
                     370.35      366.37
       TOP : SMAX=    -263.74 SMIN=    -370.35 TMAX=      53.30 ANGLE= 21.2
       BOTT: SMAX=     366.37 SMIN=     261.89 TMAX=      52.24 ANGLE=-69.1
             3         1.53        0.45      -10.40      -13.30        1.29
                     299.11      292.24       -1.83       -2.46        4.00
                     336.09      326.02
       TOP : SMAX=    -236.95 SMIN=    -336.09 TMAX=      49.57 ANGLE= 22.4
       BOTT: SMAX=     326.02 SMIN=     238.44 TMAX=      43.79 ANGLE=-71.0
          **** MAXIMUM STRESSES AMONG SELECTED PLATES AND CASES ****
             MAXIMUM       MINIMUM       MAXIMUM       MAXIMUM       MAXIMUM
            PRINCIPAL     PRINCIPAL       SHEAR       VONMISES       TRESCA
             STRESS        STRESS        STRESS        STRESS        STRESS
          3.663715E+02 -3.703516E+02  5.330365E+01  3.302169E+02  3.703516E+02
 PLATE NO.      47            47            47            47            47
 CASE  NO.       1             1             1             1             1
   ********************END OF ELEMENT FORCES********************
    83. START CONCRETE DESIGN
      STAAD SPACE                                              -- PAGE NO.    7
    * EXAMPLE PROBLEM WITH FRAME MEMBERS AND    
 CONCRETE DESIGN 
    84. CODE ACI
    85. DESIGN ELEMENT 47
      STAAD SPACE                                              -- PAGE NO.    8
    * EXAMPLE PROBLEM WITH FRAME MEMBERS AND    
    **WARNING** - ELEMENT DESIGN to ACI 318-14 is not available in this version 
 of STAAD.Pro
    86. END CONCRETE DESIGN
    87. FINI
             *********** END OF THE STAAD.Pro RUN ***********         
               **** DATE= APR 21,2020   TIME= 15:42:50 ****
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