STAAD SPACESTART JOB INFORMATIONENGINEER DATE 04-Apr-18END JOB INFORMATIONINPUT WIDTH 79UNIT FEET KIPJOINT COORDINATES1 0 0 0; 2 1.67 0 0; 3 19.66 0 0; 4 21.33 0 0; 5 1.67 -6.5 0; 6 19.66 -6.5 0;7 0.29 0 0; 8 5.33 0 0; 9 10.67 0 0; 10 16 0 0; 11 21.04 0 0; 12 0.29 0 3.67;13 0.29 0 -3.67; 14 5.33 0 3.67; 15 5.33 0 -3.67; 16 10.67 0 3.67;17 10.67 0 -3.67; 18 16 0 3.67; 19 16 0 -3.67; 20 21.04 0 3.67;21 21.04 0 -3.67;MEMBER INCIDENCES1 1 7; 2 2 5; 3 3 6; 4 7 12; 5 8 14; 6 9 16; 7 10 18; 8 11 20; 9 7 13; 10 8 15;11 9 17; 12 10 19; 13 11 21; 14 2 8; 15 3 11; 16 7 2; 17 8 9; 18 9 10; 19 10 3;20 11 4; 21 12 14; 22 14 16; 23 16 18; 24 18 20; 25 13 15; 26 15 17; 27 17 19;28 19 21;DEFINE MATERIAL STARTISOTROPIC STEELE 4.176e+006POISSON 0.3DENSITY 0.489024ALPHA 6e-006DAMP 0.03TYPE STEELSTRENGTH FY 5184 FU 8352 RY 1.5 RT 1.2END DEFINE MATERIALMEMBER PROPERTY AMERICAN1 14 TO 20 TABLE ST W10X332 3 TABLE ST W8X35MEMBER PROPERTY AMERICAN4 TO 13 PRIS YD 0.6675 ZD 0.5833 YB 0.6254 ZB 0.0254MEMBER PROPERTY AMERICAN21 TO 28 TABLE ST HSST4X2X0.375CONSTANTSMATERIAL STEEL ALLSUPPORTS5 6 FIXEDMEMBER RELEASE4 TO 13 20 START MY21 TO 28 START MY MZ21 TO 28 END MY MZ1 END MYLOAD 1 LOADTYPE Dead TITLE DLSELFWEIGHT Y -1 MEMBER LOAD*Load of Channel21 TO 28 UNI GY -0.02*10psf Load of deck plus misc on trib 5.345 TO 7 10 TO 12 UNI GY -0.0534*10psf Load of deck plus misc on trib 2.74 8 9 13 UNI GY -0.027PERFORM ANALYSISFINISH
For the cantilever W10X33 sections (joint instabilities at nodes 1 and 4), is there a need to release those short cantilevers such that they won't carry moment about their local Y? Would those not be continuous from the back span?
Similarly, you have released the MY for the WT (here prismatic T's) members, but will they be connected in such a way as to fix bending about Z but not Y? Are those member end releases necessary? That may resolve the joint instabilities at nodes 16 and 17 as well.
Jason Coleman, PE
Bentley Systems Senior Manager Technical Content
Also why I am getting instability only at Node 20,21 even though the model is symmetric. Shouldn't it show joint 13, 12, 20 and 21?