Good Day,
I have done a seismic analysis and noticed the following note:
***NOTE: SEISMIC LOAD IS ACTING AT CENTER OF MASS FOR RIGID DIAPHRAGM. TORSION FROM STATIC ECCENTRICITY (esi) IS INCLUDED IN ANALYSIS. DYNAMIC ECCENTRICITY APPLIED = DEC - 1
Does this mean only the Static Eccentricity or Accidental eccentricity is included? I have noticed that the values under DYN. Ecc. (dec) for both X and Z at all levels have a value of zero, even-though the center of mass and center of rigidity on each level is located at different x and z coordinates.
I have included a model as reference. STAIRS-FINAL FRAME DESIGN.zip
The analysis output file only reports the accidental eccentricity but the dynamic eccentricity (DEC ) is not reported which can be confusing. However the analysis does automatically consider the torsion from the dynamic eccentricity along with the accidental torsion. You just need to specify DEC and ACC parameters as part of the seismic load case and also have the rigid diaphragm defined in the model, as you have done.
Answer Verified By: Gilbert Fontenard
Hello Mr. Sye! I am interested with this post specially i want to know how to specify DEC AND ACC parameters to be part of the seismic load case.
How to do this in staad software. I'm hoping for your reply. Thanks in advance...
Please refer
https://communities.bentley.com/products/ram-staad/w/structural_analysis_and_design__wiki/21193/torsion-consideration-in-is-1893-2002-seismic-analysis
It is discussed in reference to IS1893. But the concept is the same for other code.