| Applies To | |||
| Product(s): | STAAD.Pro | ||
| Version(s): | ALL | ||
| Environment: | ALL | ||
| Area: | Analysis | ||
| Subarea: | |||
| Original Author: | Bentley Technical Support Group | ||
My hand calculations do not match the displacements being reported by STAAD.Pro. What may be causing this ?
When STAAD computes the displacement at a node using the stiffness method, the bending stiffness coefficients in the stiffness matrix include the contribution from
1) flexural deformation
2) shear distortion if it can be determined.
As a result, the joint displacements consist of the pure bending component plus the shear deformation component. Mostly when we do hand calculations we do not include the shear deformation component, and this may be responsible for the difference between STAAD's results and our expectation.
If shear deformation is eliminated from STAAD's calculations, this discrepancy will be removed. One can do that by specifying a command called SET SHEAR as shown next
STAAD SPACE
SET SHEAR
UNIT KIP FEET
JOINT COORDINATES
...
The bending coefficients will then include the contribution from flexural deformation only. It may be worth noting that the command does not affect plates and solids, and shear deformation will still be computed for those entities.