| Product(s): | RAM Structural System; Ram Frame | ||
| Version(s): | V8i | ||
| Environment: | N/A | ||
| Area: | Analysis | ||
| Original Author: | Bentley Technical Support Group |
How does changing the ground level affect restraints?
The ground level for Frame analysis can be set through Criteria - Ground level.
The default is for the model base to be the ground level. This is the bottom of the lowest story in the model story data.
The program will automatically provide a support point or restraint at the base level under every lateral column and wall. Additionally, where lateral columns or walls terminate on a higher story with nothing below them, additional support points are provided.
When you set an upper level to be the Ground Level, the program applied lateral restraint in the global X and Y directions to the diaphragm (or multiple diaphragms) at that story. This is analogous to having a vertical roller support on all the nodes attached to those diaphragms. Nodes that are disconnected from the diaphragm are no longer constrained by any ground level restraint. Any subterranean story below the ground level is also treated the same way.
How does changing the ground level affect wind and seismic loads?
In the calculation of wind and seismic loads, the program assumes the ground level as set under Criteria - Ground level is the zero elevation. All heights using in calculating wind pressures or seismic load distribution are measured up from this ground story.
See Also
RAM Frame - Building and Frame Story Shear
RAM Frame - Seismic Loads [FAQ]