Sir/Madam,
Pls. find attached two STAAD model of a steel structure.
First model is made without offset and the next model is made with an offset .
The reaction loads are different . Pls. clarify
STAAD SPACE START JOB INFORMATION ENGINEER DATE 27-Jul-21 END JOB INFORMATION INPUT WIDTH 79 UNIT MMS NEWTON JOINT COORDINATES 1 0 0 0; 2 0 -1580 0; 3 0 -1700 0; 4 -1240 -350 0; 5 445 -1580 0; MEMBER INCIDENCES 1 1 2; 2 2 3; 3 4 2; 4 2 5; DEFINE MATERIAL START ISOTROPIC STEEL E 205000 POISSON 0.3 DENSITY 7.68195e-005 ALPHA 1.2e-005 DAMP 0.03 TYPE STEEL STRENGTH FY 253.2 FU 407.8 RY 1.5 RT 1.2 ISOTROPIC RIGID E 2e+007 POISSON 0.3 END DEFINE MATERIAL MEMBER PROPERTY INDIAN 1 TO 4 TABLE FR ISMC150 CONSTANTS MATERIAL STEEL ALL SUPPORTS 1 4 FIXED LOAD 1 LOADTYPE Dead TITLE DL SELFWEIGHT Y -1 PERFORM ANALYSIS PRINT STATICS CHECK FINISH FINISH
STAAD SPACE START JOB INFORMATION ENGINEER DATE 27-Jul-21 END JOB INFORMATION INPUT WIDTH 79 UNIT MMS NEWTON JOINT COORDINATES 1 0 0 0; 2 0 -1580 0; 3 0 -1700 0; 4 -1240 -350 0; 5 445 -1580 0; MEMBER INCIDENCES 1 1 2; 2 2 3; 3 4 2; 4 2 5; DEFINE MATERIAL START ISOTROPIC STEEL E 205000 POISSON 0.3 DENSITY 7.68195e-005 ALPHA 1.2e-005 DAMP 0.03 TYPE STEEL STRENGTH FY 253.2 FU 407.8 RY 1.5 RT 1.2 ISOTROPIC RIGID E 2e+007 POISSON 0.3 END DEFINE MATERIAL MEMBER PROPERTY INDIAN 1 TO 4 TABLE FR ISMC150 CONSTANTS MATERIAL STEEL ALL SUPPORTS 1 4 FIXED MEMBER OFFSET 4 START 75 0 0 LOAD 1 LOADTYPE Dead TITLE DL SELFWEIGHT Y -1 PERFORM ANALYSIS PRINT STATICS CHECK FINISH FINISH
The selfweight of the offset distance is neglected, hence the reactions due to the selfweight are a bit different.