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Torsion on Channel below Stringer Post

Torsion on Channel below Stringer Post

Torsion on Channel below Stringer Post

(OP)
Hello,

I have a basic structural engineering question and would be really great if someone can help me understand this. So I have a rooftop platform with stairs. I have 2 posts below 2 stair stringers and the posts are sitting on 2 channels. My understanding was that I would have to brace the 2 channels on which the 2 posts are sitting so as to provide torsional stability. But in STAAD, the 2 channels (C4x4) are not getting any torsion even for a wind load case which looks fishy. Can someone please look at this code and let me know if I am doing anything wrong.

Thanks

STAAD SPACE
START JOB INFORMATION
ENGINEER DATE 19-Apr-19
END JOB INFORMATION
INPUT WIDTH 79
UNIT FEET KIP
JOINT COORDINATES
1 0 0 -0.000399272; 2 0 0 12.6667; 3 0 0.5 0; 4 0 0.5 12.6667;
8 0 1.5 -0.000399272; 9 0 1.5 7.1667; 10 0 1.5 12.6667;
15 1.5 1.5 -0.000399272; 16 1.5 1.5 12.6667; 24 13.775 1.5 3.3335;
30 26.05 1.5 -0.000399272; 31 26.05 1.5 12.6667; 32 27.55 0 -0.000399272;
33 27.55 0 12.6667; 34 27.55 0.5 0; 35 27.55 0.5 12.6667;
39 27.55 1.5 -0.000399272; 49 27.55 1.5 11.1667; 50 0 1.5 11.1667;
51 27.55 1.5 1.4996; 52 0 1.5 1.4996; 62 0 1.5 6.6667; 64 1.5 1.5 6.6667;
66 26.05 1.5 6.6667; 67 37.0497 -0.5 9.167; 69 37.0497 -0.5 12.667;
75 6.8 1.5 12.6667; 77 27.55 1.5 6.6667; 79 27.55 1.5 12.6667;
82 6.8 7 12.6667; 92 18.8003 1.5 12.6667; 96 18.8002 7 12.6667;
100 27.55 1.5 7.1667; 102 18.8 1.5 7.1667; 103 6.8 1.5 7.1667;
104 6.8 7 7.1667; 105 27.55 7 7.1667; 106 18.8 7 7.1667; 110 40.5493 0 9.167;
111 40.5493 0 12.667; 119 12.8003 7 12.6667; 120 18.8 7 6.6667;
121 6.8 7 6.6667; 122 27.55 7 6.6667; 123 12.8 7 6.6667; 124 6.8 6.5 7.1667;
125 27.55 6.5 7.1667; 126 18.8 6.5 7.1667; 127 23.1753 7 12.6667;
128 23.175 7 6.6667; 130 16.05 0 -0.000399272; 131 16.05 1.5 -0.000399272;
134 16.05 0 12.6666; 135 16.05 1.5 12.6667; 136 27.55 7 12.6667;
137 27.55 7 9.1667; 138 16.05 1.5 6.6667; 139 16.05 1.5 7.1667;
146 37.0497 1.88487 9.167; 147 37.0497 1.88487 12.667;
148 32.3018 4.44186 12.6668; 149 32.3018 4.44186 9.16685;
150 41.0497 -0.5 9.167; 151 41.0497 -0.5 12.667; 152 36.0497 -0.5 9.167;
153 36.0497 -0.5 12.667;
MEMBER INCIDENCES
1 3 1; 2 4 2; 3 8 3; 4 10 4; 5 9 62; 10 9 50; 17 15 3; 18 16 4; 19 8 15;
20 10 16; 35 15 131; 36 100 102; 37 31 92; 47 30 34; 48 31 35; 49 30 39;
50 31 79; 51 34 32; 52 35 33; 53 39 34; 54 79 35; 55 100 77; 61 49 100;
91 49 79; 92 35 49; 93 50 10; 94 4 50; 95 51 39; 96 34 51; 97 52 8; 98 3 52;
104 77 66; 105 77 51; 107 62 52; 108 15 64; 109 64 62; 111 30 66; 112 66 138;
113 67 146; 114 69 147; 118 103 124; 119 75 82; 120 100 125; 121 79 136;
122 137 149; 123 136 148; 125 121 123; 132 137 136; 134 102 126; 135 92 96;
148 75 16; 150 92 135; 152 102 139; 153 103 9; 154 104 82; 156 106 96;
158 120 128; 161 123 120; 165 119 123; 166 82 119; 167 96 127; 168 119 96;
169 105 122; 170 106 120; 172 104 121; 173 124 104; 174 125 105; 175 126 106;
176 124 121; 177 126 120; 179 125 122; 180 127 136; 181 128 122; 182 127 128;
183 130 131; 184 131 30; 187 135 75; 188 134 135; 189 137 105; 190 135 139;
191 138 64; 192 139 103; 193 138 131; 194 139 138; 205 147 146; 206 148 147;
207 149 146; 210 148 149; 215 146 110; 216 147 111; 217 149 147; 218 153 69;
219 69 151; 220 152 67; 221 67 150;
DEFINE MATERIAL START
ISOTROPIC STEEL
E 4.176e+006
POISSON 0.3
DENSITY 0.489024
ALPHA 6e-006
DAMP 0.03
TYPE STEEL
STRENGTH FY 5184 FU 8352 RY 1.5 RT 1.2
ISOTROPIC CONCRETE
E 453600
POISSON 0.17
DENSITY 0.150336
ALPHA 5e-006
DAMP 0.05
TYPE CONCRETE
STRENGTH FCU 576
END DEFINE MATERIAL
MEMBER PROPERTY AMERICAN
108 111 132 154 156 165 169 170 172 182 189 TABLE ST C4X7
1 TO 4 51 TO 54 183 188 TABLE ST HSST6X6X0.5
MEMBER PROPERTY AMERICAN
17 18 47 48 92 94 96 98 176 177 179 TABLE ST L30308
5 10 19 20 35 TO 37 49 50 55 61 91 93 95 97 104 105 107 109 112 148 150 152 -
153 184 187 190 TO 194 TABLE ST W12X45
125 158 161 166 TO 168 180 181 TABLE ST MC4X13
113 114 118 TO 121 134 135 173 TO 175 TABLE ST HSST3X3X0.375
122 123 206 207 215 216 TABLE ST C12X25
MEMBER PROPERTY AMERICAN
205 210 217 TABLE ST L30204
218 TO 221 TABLE ST C4X4
CONSTANTS
BETA 45 MEMB 17 18 47 48 92 94 96 98 176 177 179 205 210 217
BETA 180 MEMB 122 207 215
MATERIAL STEEL ALL
SUPPORTS
1 2 32 33 130 134 150 TO 153 PINNED
120 TO 122 FIXED BUT FX FY MX MY MZ
MEMBER RELEASE
19 20 36 104 108 111 123 165 182 184 187 191 192 205 210 217 START MY MZ
35 49 50 108 109 111 112 132 150 152 TO 154 156 165 169 170 172 182 205 210 -
217 END MY MZ
122 START FX MY MZ
MEMBER TRUSS
17 18 47 48 92 94 96 98 176 177 179
SLAVE ZX MASTER 24 JOINT 15 30 64 66
LOAD 1 LOADTYPE Dead TITLE DL
SELFWEIGHT Y -1
MEMBER LOAD
*Unit Weight on Dunnage
19 35 49 104 109 112 184 191 UNI GY -0.22
*Grating Weight on Elevated Platform
156 165 170 182 UNI GY -0.048
132 154 169 172 189 UNI GY -0.024
*Grating Weight on Stairs
122 123 206 207 215 216 UNI GY -0.014
LOAD 2 LOADTYPE Roof Live TITLE LR
MEMBER LOAD
*Load on Elevated Platform Channels for 60psf live load
156 165 170 182 UNI GY -0.36
132 154 169 172 189 UNI GY -0.18
*Load on Stair for 60psf live load
122 123 206 207 215 216 UNI GY -0.175
LOAD 3 LOADTYPE Roof Live TITLE LRCONC
MEMBER LOAD
*Load on Elevated Platform Channels for 60psf live load
156 165 170 182 UNI GY -0.36
132 154 169 172 189 UNI GY -0.18
*Load on Stair for 1000lbf concentrated live load
122 CON GY -1 0.5
LOAD 4 LOADTYPE Snow TITLE SL
MEMBER LOAD
*Equipment snow load on Dunnage
19 35 49 104 109 112 184 191 UNI GY -0.07
*21 psf Balanced Snow Load on elevated platform channels
156 165 170 182 UNI GY -0.13
132 154 169 172 189 UNI GY -0.065
*21 psf Balanced Snow Load on stringer
122 123 206 207 215 216 UNI GY -0.04
LOAD 5 LOADTYPE Snow TITLE SL DRIFT
MEMBER LOAD
*Drift load on middle channels in elevated platform
170 TRAP GY -0.1665 -0.18
156 TRAP GY -0.1665 -0.02
165 182 TRAP GY -0.02 -0.18
*Drift load on corner channels in elevated platform
169 172 TRAP GY -0.08425 -0.09
154 TRAP GY -0.08425 -0.01
189 TRAP GY -0.066964 -0.08425
132 TRAP GY -0.066964 -0.01
LOAD 6 LOADTYPE Ice TITLE IL
MEMBER LOAD
*Grating load on elevated platform channels
156 165 170 182 UNI GY -0.12
132 154 169 172 189 UNI GY -0.06
*Grating load on stairs
122 123 206 207 215 216 UNI GY -0.035
*Equipment load on dunnage
19 35 49 104 109 112 184 191 UNI GY -0.05
*Misc. steel member ice loads
5 10 19 20 35 TO 37 49 50 55 61 91 93 95 97 104 105 107 109 112 148 150 152 -
153 184 187 190 TO 194 UNI GY -0.037
17 18 47 48 92 94 96 98 176 177 179 205 210 217 UNI GY -0.011
108 111 125 132 154 156 158 161 165 TO 170 172 180 TO 182 189 UNI GY -0.013
122 123 206 207 215 216 UNI GY -0.026
113 114 118 TO 121 134 135 173 TO 175 UNI GY -0.013
1 TO 4 51 TO 54 183 188 UNI GY -0.02
LOAD 7 LOADTYPE Wind TITLE WIND +X
MEMBER LOAD
19 35 49 104 109 112 184 191 UMOM GZ -0.5
19 35 49 104 109 112 184 191 UNI GX 0.1
122 123 206 207 215 216 UNI GX 0.021
1 TO 4 51 TO 54 183 188 UNI GX 0.04
113 114 118 TO 121 134 135 173 174 UNI GX 0.02
154 172 UNI GX 0.027
94 98 176 205 210 217 UNI GX 0.02
5 10 93 97 107 UNI GX 0.08
LOAD 8 LOADTYPE Wind TITLE WIND -X
MEMBER LOAD
19 35 49 104 109 112 184 191 UMOM GZ 0.5
19 35 49 104 109 112 184 191 UNI GX -0.1
122 123 206 207 215 216 UNI GX -0.021
1 TO 4 51 TO 54 183 188 UNI GX -0.04
113 114 118 TO 121 134 135 173 174 UNI GX -0.02
132 169 189 UNI GX -0.03
92 96 179 205 210 217 UNI GX -0.02
55 61 91 95 105 UNI GX -0.08
LOAD 9 LOADTYPE Wind TITLE WIND +Z
MEMBER LOAD
19 35 49 104 109 112 184 191 UNI GZ 0.4
19 35 49 184 UNI GY 0.55
104 109 112 191 UNI GY -0.55
122 207 215 UNI GZ 0.085
1 3 51 53 183 UNI GZ 0.043
113 UNI GZ 0.022
17 47 UNI GZ 0.022
19 35 49 184 UNI GZ 0.085
LOAD 10 LOADTYPE Wind TITLE WIND -Z
MEMBER LOAD
19 35 49 104 109 112 184 191 UNI GZ -0.4
104 109 112 191 UNI GY 0.55
19 35 49 184 UNI GY -0.55
123 206 216 UNI GZ -0.085
2 4 52 54 188 UNI GZ -0.043
114 119 121 135 UNI GZ -0.022
18 48 UNI GZ -0.022
20 37 50 148 150 187 UNI GZ -0.085
166 TO 168 180 UNI GZ -0.029
LOAD 11 LOADTYPE Wind on Ice TITLE WIL+X
MEMBER LOAD
122 123 206 207 215 216 UNI GX 0.009
1 TO 4 UNI GX 0.013
154 172 UNI GX 0.01
94 98 176 205 210 217 UNI GX 0.005
5 10 93 97 107 UNI GX 0.017
113 114 118 119 173 UNI GX 0.0083
LOAD 12 LOADTYPE Wind on Ice TITLE WIL-X
MEMBER LOAD
122 123 206 207 215 216 UNI GX -0.009
51 TO 54 UNI GX -0.013
113 114 120 121 174 UNI GX -0.0083
132 169 189 UNI GX -0.01
92 96 179 205 210 217 UNI GX -0.005
55 61 91 95 105 UNI GX -0.017
LOAD 13 LOADTYPE Wind on Ice TITLE WIL+Z
MEMBER LOAD
122 207 215 UNI GZ 0.022
1 TO 4 51 TO 54 183 188 UNI GZ 0.013
113 UNI GZ 0.009
17 47 UNI GZ 0.005
19 35 49 184 UNI GZ 0.018
LOAD 14 LOADTYPE Wind on Ice TITLE WIL-Z
MEMBER LOAD
123 206 216 UNI GZ -0.022
1 TO 4 51 TO 54 183 188 UNI GZ -0.013
114 119 121 135 UNI GZ -0.009
18 48 UNI GZ -0.005
20 37 50 148 150 187 UNI GZ -0.018
166 TO 168 180 UNI GZ -0.011
LOAD 15 LOADTYPE Seismic TITLE EL+X
NOTIONAL LOAD
1 X 0.28
MEMBER LOAD
19 35 49 104 109 112 184 191 UMOM GZ -0.3
LOAD 16 LOADTYPE Seismic TITLE EL-X
NOTIONAL LOAD
1 X -0.28
MEMBER LOAD
19 35 49 104 109 112 184 191 UMOM GZ 0.3
LOAD 17 LOADTYPE Seismic TITLE EL+Z
NOTIONAL LOAD
1 Z 0.28
MEMBER LOAD
19 35 49 184 UNI GY 0.1
104 109 112 191 UNI GY -0.1
LOAD 18 LOADTYPE Seismic TITLE EL-Z
NOTIONAL LOAD
1 Z -0.28
MEMBER LOAD
104 109 112 191 UNI GY 0.1
19 35 49 184 UNI GY -0.1
LOAD 19 LOADTYPE Seismic TITLE EL VERTICAL
NOTIONAL LOAD
1 Y -0.06
LOAD COMB 101 D
1 1.0
LOAD COMB 102 D+LR
1 1.0 2 1.0
LOAD COMB 103 D+LR2
1 1.0 3 1.0
LOAD COMB 104 D+S
1 1.0 4 1.0 5 1.0
LOAD COMB 105 D+0.75LR
1 1.0 2 0.75
LOAD COMB 106 D+0.75LR2
1 1.0 3 0.75
LOAD COMB 107 D+0.75S
1 1.0 4 0.75 5 0.75
LOAD COMB 108 D+WX+
1 1.0 7 1.0
LOAD COMB 109 D+WX-
1 1.0 8 1.0
LOAD COMB 110 D+WZ+
1 1.0 9 1.0
LOAD COMB 111 D+WZ-
1 1.0 10 1.0
LOAD COMB 112 D+0.7EX++EVERT
1 1.0 15 0.7 19 1.0
LOAD COMB 113 D+0.7EX-+EVERT
1 1.0 16 0.7 19 1.0
LOAD COMB 114 D+0.7EZ++EVERT
1 1.0 17 0.7 19 1.0
LOAD COMB 115 D+0.7EZ-+EVERT
1 1.0 18 0.7 19 1.0
LOAD COMB 116 D+0.75WX++0.75LR
1 1.0 7 0.75 2 0.75
LOAD COMB 117 D+0.75WX-+0.75LR
1 1.0 8 0.75 2 0.75
LOAD COMB 118 D+0.75WZ++0.75LR
1 1.0 9 0.75 2 0.75
LOAD COMB 119 D+0.75WZ-+0.75LR
1 1.0 10 0.75 2 0.75
LOAD COMB 120 D+0.75WX++0.75LR2
1 1.0 7 0.75 3 0.75
LOAD COMB 121 D+0.75WX-+0.75LR2
1 1.0 8 0.75 3 0.75
LOAD COMB 122 D+0.75WZ++0.75LR2
1 1.0 9 0.75 3 0.75
LOAD COMB 123 D+0.75WZ-+0.75LR2
1 1.0 10 0.75 3 0.75
LOAD COMB 124 D+0.525EX++0.75LR+EVERT
1 1.0 15 0.525 2 0.75 19 1.0
LOAD COMB 125 D+0.525EX-+0.75LR+EVERT
1 1.0 16 0.525 2 0.75 19 1.0
LOAD COMB 126 D+0.525EZ++0.75LR+EVERT
1 1.0 17 0.525 2 0.75 19 1.0
LOAD COMB 127 D+0.525EZ-+0.75LR+EVERT
1 1.0 18 0.525 2 0.75 19 1.0
LOAD COMB 128 D+0.525EX++0.75LR2+EVERT
1 1.0 15 0.525 3 0.75 19 1.0
LOAD COMB 129 D+0.525EX-+0.75LR2+EVERT
1 1.0 16 0.525 3 0.75 19 1.0
LOAD COMB 130 D+0.525EZ++0.75LR2+EVERT
1 1.0 17 0.525 3 0.75 19 1.0
LOAD COMB 131 D+0.525EZ-+0.75LR2+EVERT
1 1.0 18 0.525 3 0.75 19 1.0
LOAD COMB 132 D+0.75WX++0.75S
1 1.0 7 0.75 4 0.75 5 0.75
LOAD COMB 133 D+0.75WX-+0.75S
1 1.0 8 0.75 4 0.75 5 0.75
LOAD COMB 134 D+0.75WZ++0.75S
1 1.0 9 0.75 4 0.75 5 0.75
LOAD COMB 135 D+0.75WZ-+0.75S
1 1.0 10 0.75 4 0.75 5 0.75
LOAD COMB 136 D+0.525EX++0.75S+EVERT
1 1.0 15 0.525 4 0.75 5 0.75 19 1.0
LOAD COMB 137 D+0.525EX-+0.75S+EVERT
1 1.0 16 0.525 4 0.75 5 0.75 19 1.0
LOAD COMB 138 D+0.525EZ++0.75S+EVERT
1 1.0 17 0.525 4 0.75 5 0.75 19 1.0
LOAD COMB 139 D+0.525EZ-+0.75S+EVERT
1 1.0 18 0.525 4 0.75 5 0.75 19 1.0
LOAD COMB 140 0.6D+WX+
1 0.6 7 1.0
LOAD COMB 141 0.6D+WX-
1 0.6 8 1.0
LOAD COMB 142 0.6D+WZ+
1 0.6 9 1.0
LOAD COMB 143 0.6D+WZ-
1 0.6 10 1.0
LOAD COMB 144 0.6D+0.7EX+-EVERT
1 0.6 15 0.7 19 -1.0
LOAD COMB 145 0.6D+0.7EX--EVERT
1 0.6 16 0.7 19 -1.0
LOAD COMB 146 0.6D+0.7EZ+-EVERT
1 0.6 17 0.7 19 -1.0
LOAD COMB 147 0.6D+0.7EZ--EVERT
1 0.6 18 0.7 19 -1.0
LOAD COMB 201 D+0.7IL
1 1.0 6 0.7
LOAD COMB 202 D+0.7IL+0.7WILX++S
1 1.0 6 0.7 11 0.7 4 1.0 5 1.0
LOAD COMB 203 D+0.7IL+0.7WILX-+S
1 1.0 6 0.7 12 0.7 4 1.0 5 1.0
LOAD COMB 204 D+0.7IL+0.7WILZ++S
1 1.0 6 0.7 13 0.7 4 1.0 5 1.0
LOAD COMB 205 D+0.7IL+0.7WILZ-+S
1 1.0 6 0.7 14 0.7 4 1.0 5 1.0
LOAD COMB 206 D+0.7IL+0.7WILX+
1 1.0 6 0.7 11 0.7
LOAD COMB 207 D+0.7IL+0.7WILX-
1 1.0 6 0.7 12 0.7
LOAD COMB 208 D+0.7IL+0.7WILZ+
1 1.0 6 0.7 13 0.7
LOAD COMB 209 D+0.7IL+0.7WILZ-
1 1.0 6 0.7 14 0.7
LOAD COMB 301 1.4D
1 1.4
LOAD COMB 302 1.2D+0.5LR
1 1.2 2 0.5
LOAD COMB 303 1.2D+0.5LR2
1 1.2 3 0.5
LOAD COMB 304 1.2D+0.5S
1 1.2 4 0.5 5 0.5
LOAD COMB 305 1.2D+1.6LR+0.8WX+
1 1.2 2 1.6 7 0.8
LOAD COMB 306 1.2D+1.6LR+0.8WX-
1 1.2 2 1.6 8 0.8
LOAD COMB 307 1.2D+1.6LR+0.8WZ+
1 1.2 2 1.6 9 0.8
LOAD COMB 308 1.2D+1.6LR+0.8WZ-
1 1.2 2 1.6 10 0.8
LOAD COMB 309 1.2D+1.6LR2+0.8WX+
1 1.2 3 1.6 7 0.8
LOAD COMB 310 1.2D+1.6LR2+0.8WX-
1 1.2 3 1.6 8 0.8
LOAD COMB 311 1.2D+1.6LR2+0.8WZ+
1 1.2 3 1.6 9 0.8
LOAD COMB 312 1.2D+1.6LR2+0.8WZ-
1 1.2 3 1.6 10 0.8
LOAD COMB 313 1.2D+1.6S+0.8WX+
1 1.2 4 1.6 5 1.6 7 0.8
LOAD COMB 314 1.2D+1.6S+0.8WX-
1 1.2 4 1.6 5 1.6 8 0.8
LOAD COMB 315 1.2D+1.6S+0.8WZ+
1 1.2 4 1.6 5 1.6 9 0.8
LOAD COMB 316 1.2D+1.6S+0.8WZ-
1 1.2 4 1.6 5 1.6 10 0.8
LOAD COMB 317 1.2D+0.5LR+1.6WX+
1 1.2 2 0.5 7 1.6
LOAD COMB 318 1.2D+0.5LR+1.6WX-
1 1.2 2 0.5 8 1.6
LOAD COMB 319 1.2D+0.5LR+1.6WZ+
1 1.2 2 0.5 9 1.6
LOAD COMB 320 1.2D+0.5LR+1.6WZ-
1 1.2 2 0.5 10 1.6
LOAD COMB 321 1.2D+0.5LR2+1.6WX+
1 1.2 3 0.5 7 1.6
LOAD COMB 322 1.2D+0.5LR2+1.6WX-
1 1.2 3 0.5 8 1.6
LOAD COMB 323 1.2D+0.5LR2+1.6WZ+
1 1.2 3 0.5 9 1.6
LOAD COMB 324 1.2D+0.5LR2+1.6WZ-
1 1.2 3 0.5 10 1.6
LOAD COMB 325 1.2D+0.5S+1.6WX+
1 1.2 4 0.5 5 0.5 7 1.6
LOAD COMB 326 1.2D+0.5S+1.6WX-
1 1.2 4 0.5 5 0.5 8 1.6
LOAD COMB 327 1.2D+0.5S+1.6WZ+
1 1.2 4 0.5 5 0.5 9 1.6
LOAD COMB 328 1.2D+0.5S+1.6WZ-
1 1.2 4 0.5 5 0.5 10 1.6
LOAD COMB 329 1.2D+EX++0.2S+EVERT
1 1.2 15 1.0 4 0.2 5 0.2 19 1.0
LOAD COMB 330 1.2D+EX-+0.2S+EVERT
1 1.2 16 1.0 4 0.2 5 0.2 19 1.0
LOAD COMB 331 1.2D+EZ++0.2S+EVERT
1 1.2 17 1.0 4 0.2 5 0.2 19 1.0
LOAD COMB 332 1.2D+EZ-+0.2S+EVERT
1 1.0 18 1.0 4 1.0 5 1.0 19 1.0
LOAD COMB 333 0.9D+1.6WX+
1 0.9 7 1.6
LOAD COMB 334 0.9D+1.6WX-
1 0.9 8 1.6
LOAD COMB 335 0.9D+1.6WZ+
1 0.9 9 1.6
LOAD COMB 336 0.9D+1.6WZ-
1 0.9 10 1.6
LOAD COMB 337 0.9D+EX+-EVERT
1 0.9 15 1.6 19 -1.0
LOAD COMB 338 0.9D+EX--EVERT
1 0.9 16 1.6 19 -1.0
LOAD COMB 339 0.9D+EZ+-EVERT
1 0.9 17 1.6 19 -1.0
LOAD COMB 340 0.9D+EZ--EVERT
1 0.9 18 1.6 19 -1.0
LOAD COMB 401 1.2D+0.2I+0.5S
1 1.2 6 0.2 4 0.5 5 0.5
LOAD COMB 402 1.2D+I+WIX++0.5S
1 1.2 6 1.0 11 1.0 4 0.5 5 0.5
LOAD COMB 403 1.2D+I+WIX-+0.5S
1 1.2 6 1.0 12 1.0 4 0.5 5 0.5
LOAD COMB 404 1.2D+I+WIZ++0.5S
1 1.2 6 1.0 13 1.0 4 0.5 5 0.5
LOAD COMB 405 1.2D+I+WIZ-+0.5S
1 1.2 6 1.0 14 1.0 4 0.5 5 0.5
LOAD COMB 406 0.9D+I+WIX+
1 0.9 6 1.0 11 1.0
LOAD COMB 407 0.9D+I+WIX-
1 0.9 6 1.0 12 1.0
LOAD COMB 408 0.9D+I+WIZ+
1 0.9 6 1.0 13 1.0
LOAD COMB 409 0.9D+I+WIZ-
1 0.9 6 1.0 14 1.0
PERFORM ANALYSIS
DEFINE ENVELOPE
101 TO 147 201 TO 209 ENVELOPE 1 TYPE SERVICEABILITY
301 TO 340 401 TO 409 ENVELOPE 2 TYPE STRENGTH
END DEFINE ENVELOPE
LOAD LIST ENV 1 2
PARAMETER 1
CODE AISC UNIFIED 2010
TORSION 1 MEMB 218 TO 221
METHOD LRFD
FU 9360 MEMB 5 10 19 20 35 TO 37 49 50 55 61 91 93 95 97 104 105 107 109 112 -
148 150 152 153 184 187 190 TO 194 218 TO 221
FU 8352 MEMB 1 TO 4 17 18 47 48 51 TO 54 92 94 96 98 108 111 113 114 -
118 TO 123 125 132 134 135 154 156 158 161 165 TO 170 172 TO 177 179 TO 183 -
188 189 205 TO 207 210 215 TO 217
FYLD 7200 MEMB 5 10 19 20 35 TO 37 49 50 55 61 91 93 95 97 104 105 107 109 -
112 148 150 152 153 184 187 190 TO 194 218 TO 221
FYLD 6624 MEMB 1 TO 4 51 TO 54 113 114 118 TO 121 134 135 173 TO 175 183 188
FYLD 5184 MEMB 17 18 47 48 92 94 96 98 108 111 122 123 125 132 154 156 158 -
161 165 TO 170 172 176 177 179 TO 182 189 205 TO 207 210 215 TO 217
DJ2 39 MEMB 51 53
DJ1 32 MEMB 51 53
DJ2 1 MEMB 1 3
DJ1 8 MEMB 1 3
DJ2 39 MEMB 55 61 91 95 105
DJ1 79 MEMB 55 61 91 95 105
DJ2 8 MEMB 5 10 93 97 107
DJ1 10 MEMB 5 10 93 97 107
DJ2 33 MEMB 52 54
DJ1 79 MEMB 52 54
DJ2 2 MEMB 2 4
DJ1 10 MEMB 2 4
DJ2 111 MEMB 123 206 216
DJ1 136 MEMB 123 206 216
DJ2 110 MEMB 122 207 215
DJ1 137 MEMB 122 207 215
DJ2 104 MEMB 118 173
DJ1 103 MEMB 118 173
DJ2 106 MEMB 134 175
DJ1 102 MEMB 134 175
DJ2 105 MEMB 120 174
DJ1 100 MEMB 120 174
DJ2 135 MEMB 190 193 194
DJ1 131 MEMB 190 193 194
DJ1 39 MEMB 49 184
DJ2 131 MEMB 49 184
DJ2 131 MEMB 19 35
DJ1 8 MEMB 19 35
DJ1 79 MEMB 37 50 150
DJ2 135 MEMB 37 50 150
DJ2 135 MEMB 20 148 187
DJ1 10 MEMB 20 148 187
DJ1 100 MEMB 36 152
DJ2 139 MEMB 36 152
DJ2 139 MEMB 153 192
DJ1 9 MEMB 153 192
DJ1 77 MEMB 104 112
DJ2 138 MEMB 104 112
DJ2 138 MEMB 109 191
DJ1 62 MEMB 109 191
DJ2 82 MEMB 166 TO 168 180
DJ1 136 MEMB 166 TO 168 180
DJ2 122 MEMB 125 158 161 181
DJ1 121 MEMB 125 158 161 181
DFF 360 ALL
LZ 6.67 MEMB 5 10 55 61 91 93 95 97 105 107 190 193 194
LZ 5 MEMB 122 123 206 207 215 216
LZ 15 MEMB 19 20 35 TO 37 49 50 104 109 112 148 150 152 153 184 187 191 192
LY 16 MEMB 19 20 35 37 49 50 148 150 184 187
LY 27.5 MEMB 36 104 109 112 152 153 191 192
LY 12.5 MEMB 5 10 55 61 91 93 95 97 105 107
LY 12 MEMB 125 158 161 166 TO 168 180 181
LY 12 MEMB 122 123 206 207 215 216
LY 5.5 MEMB 132 154 156 169 170 172 189
KZ 2 MEMB 1 TO 4 51 TO 54 113 114 118 TO 121 134 135 173 TO 175 183 188
KY 2 MEMB 1 TO 4 51 TO 54 113 114 118 TO 121 134 135 173 TO 175 183 188
CHECK CODE ALL
FINISH

RE: Torsion on Channel below Stringer Post

(OP)
Great. Thanks

RE: Torsion on Channel below Stringer Post

The C4 is pinned at the ends so there is no rotational restraint thats why you dont have torsion in the channel. Also what the connection of the HSS 3x3 to the C4. The C4 only has a ~ 1 1/2" flange ie not much. Is it free to slide?

RE: Torsion on Channel below Stringer Post

(OP)
Actually, I took C4 just to test if STAAD will show any torsion or not. I am not using C4 in real design because it has smaller flange. Connection between HSS and a bigger channel is going to be weld. SO I was expecting torsion because there is wind on those HSS members (external posts). Someone told me that STAAD doesn't take into account induced torsion. Just want to make sure that's the case.

RE: Torsion on Channel below Stringer Post

Quote (cgstrucg)

Someone told me that STAAD doesn't take into account induced torsion.

I'm not sure exactly what that means. My thoughts on the subject:
1) Torsional warping of wide flange and channel members is a pretty complex issue. I don't know that you can rely on any of the major commercial programs to fully account for it.
2) By fully account for it I mean that it would need to
a) Include the increased torsional stiffness due to the warping effect.
b) Include the ability to set warping restraint at the ends of a member. Effectively introducing a 7th degree of freedom to the joint.
c) Include the effect of torsional warping stresses on member code checks.
3) I always recommend that when you know your wide flange or channel is going to experience warping you do a hand calculation. Maybe per AISC DG - 9 or the British Design Gide (Design of Steel Beams in Torsion: SCI P385). To me the British one is a bit better and more realistic.
4) Better yet, use something akin to the "equivalent tee" analogy for your hand calc.

RE: Torsion on Channel below Stringer Post

If you change your support from pinned to fixed then you will be torsion. But your end restraint should be match your design conditions/assumptions. And I agree with JoshPlum don't use STAAD to do the design check if you do have torsion.

RE: Torsion on Channel below Stringer Post

Quote:

Someone told me that STAAD doesn't take into account induced torsion. Just want to make sure that's the case.

STAAD does calculate the torsional force......but it won't check the steel member for that force (including warping and so forth) without the proper input command.

RE: Torsion on Channel below Stringer Post

(OP)
WARose - Is there a command to make STAAD account for torsion for specific steel members. I did use the "Torsion Design" command for that C4 member and that doesn't seem to help. The weird part is that in results, for those C4 members, STAAD doesn't show any torsional force while in real life there will be torsion because of Wind in those C4 channels.

As JoshPlum mentioned, I am going to do a handcalc to actually understand the design concept.

RE: Torsion on Channel below Stringer Post

Quote:

WARose - Is there a command to make STAAD account for torsion for specific steel members. I did use the "Torsion Design" command for that C4 member and that doesn't seem to help. The weird part is that in results, for those C4 members, STAAD doesn't show any torsional force while in real life there will be torsion because of Wind in those C4 channels.

You have the command in there. When I ran it on my end, it wasn't checking torsion for me either because (like another poster mentioned) you need to change your supports to fixed so you can get some torsion.

Running it with nodes 150 to 153 fixed.....the torsion checks are done. (See the post-processing file.)

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