| Applies To | |||
| Product(s): | STAAD.Pro | ||
| Version(s): | All | ||
| Environment: | N/A | ||
| Area: | STAAD.Pro Analysis Solution | ||
| Subarea: | Seismic Analysis | ||
| Original Author: | SANJIB DAS, Global Technical Support Group | ||
By default, STAAD considers translational mass while forming mass matrix. No rotational mass is considered if any moment is applied as member loading in the model. A sample model has been attached (Demo_1.std), since in the model only rotational mass is present as concentrated moments used as member loading the program faces problem with mass matrix formation since all elements are zero. A error will be reported.
If you want to consider rotational mass, you need to issue SET MASS 1 command which will include rotational mass in mass matrix. You can refer to Demo_2.std. In real life model rotational mass has little effect. It is the translational mass which contributes to the mass participation.