Current Revision posted to RAM | STAAD Wiki by Sye on 6/10/2016 8:26:28 PM
Applies To | |||
Product(s): | STAAD.Pro | ||
Version(s): | All | ||
Environment: | N/A | ||
Area: | Analysis | ||
Subarea: | Response Spectrum Analysis | ||
Original Author: | Bentley Technical Support Group | ||
In the output file of a response spectrum analysis, there is the section that shows the mass participation factors in the x, y, and z directions. Then it shows the 'base shear' in all 3 directions. What is the reference point for this? I mean, does Staad select a 'base' or is the value just the sum of all forces in that particular direction?
Each mode has a base shear that comes from the modal displacement at each joint with mass in the direction being excited by the base acceleration and the input spectral acceleration and the modal frequency. These modal base shears are combined by SRSS or any other method in STAAD that you select. In effect, all supported joint directions form the base where the displacement of every mode is zero.
Tags: base shear, response spectrum analysis