Please see STAAD input command below. I try to change DFF parameter in any value (not 0) but the result still show all member pass all code check.
Please verify if I'm wrong...
Best regard.
STAAD SPACE
START JOB INFORMATION
ENGINEER DATE 06-Feb-16
END JOB INFORMATION
INPUT WIDTH 79
UNIT METER KG
JOINT COORDINATES
1 0 5 0; 2 10 5 0; 3 0 4.91 1.7; 4 10 4.91 1.7; 5 0 4.93656 1.19832;
6 10 4.93656 1.19832; 7 0 3.8 0; 8 10 3.8 0; 9 0 4.99207 0.14979;
10 10 4.99207 0.14979; 11 0 4.9511 0.923706; 12 10 4.9511 0.923706;
MEMBER INCIDENCES
1 1 9; 2 2 10; 3 3 4; 4 5 3; 5 6 4; 6 7 5; 7 8 6; 8 9 11; 9 10 12; 10 9 10;
11 11 5; 12 12 6; 13 11 12;
START GROUP DEFINITION
FLOOR
_CP1 3 TO 5 8 TO 13
END GROUP DEFINITION
DEFINE MATERIAL START
ISOTROPIC STEEL
E 2.09042e+010
POISSON 0.3
DENSITY 7833.41
ALPHA 1.2e-005
DAMP 0.03
TYPE STEEL
STRENGTH FY 2.58192e+007 FU 4.1584e+007 RY 1.5 RT 1.2
END DEFINE MATERIAL
MEMBER PROPERTY JAPANESE
1 2 4 5 8 9 11 12 TABLE ST C150X75X9
3 10 13 TABLE ST RHS150X75X2.3
6 7 TABLE ST C100X50X5
CONSTANTS
BETA 180 MEMB 2 5 7 9 12
MATERIAL STEEL ALL
SUPPORTS
1 2 7 8 PINNED
LOAD 1 LOADTYPE None TITLE DL
SELFWEIGHT Y -1
FLOOR LOAD
_CP1 FLOAD -10 GY
LOAD 2 LOADTYPE None TITLE LR
FLOOR LOAD
_CP1 FLOAD -30 GY
LOAD 3 LOADTYPE None TITLE WX
FLOOR LOAD
_CP1 FLOAD 50 GY
LOAD 4 LOADTYPE None TITLE WZ
FLOOR LOAD
_CP1 FLOAD 70 GY
LOAD COMB 101 DL+LR
1 1.0 2 1.0
LOAD COMB 102 DL+0.75[LR+WX]
1 1.0 2 0.75 3 0.75
LOAD COMB 103 DL+0.75[LR+WZ]
1 1.0 2 0.75 4 0.75
LOAD COMB 104 DL+WX
1 1.0 3 1.0
LOAD COMB 105 DL+WZ
1 1.0 4 1.0
LOAD COMB 106 0.6DL+WX
1 0.6 3 1.0
LOAD COMB 107 0.6DL+WZ
1 0.6 4 1.0
PERFORM ANALYSIS
LOAD LIST 101 TO 107
PARAMETER 1
CODE AISC UNIFIED 2005
METHOD ASD
MAIN 1 MEMB 3 10 13
TMAIN 1 MEMB 3 10 13
*LY 5 MEMB 3 10 13
DFF 1000 MEMB 3 10 13
DJ1 9 MEMB 10
DJ2 12 MEMB 10
CHECK CODE ALL
FINISH