The procedure used by SAP2000 for the bridge substructure seismic design is documented in Automated seismic design of bridges based on AASHTO guide specifications for LRFD seismic bridge design manual. The structure displacement demand is calculated based on Article 4.8 of the AASHTO Guide Specifications for LRFD Seismic Bridge Design.

Applicability

The design implemented in SAP2000 is applicable for reinforced concrete columns.

Seismic Design Category

Seismic design category is determined in accordance with AASHTO Article 3.5, based on the value of one second period design spectral acceleration.

Hinges

The program creates Caltrans hinges for bridge seismic design request, but Caltrans hinges are only available for Section Designer section, regular rectangular sections or circular section. Therefore, the column section should be one of the sections for which Caltrans hinges can be generated.

Pushover Analysis

Sometimes, the pushover analysis may not get completed, because the structure is being pushed beyond its capacity and it becomes unstable, thus causing numerical problems and the analysis being terminated prior to reaching the full target displacement. However, the calculated pushover capacity displacements are still correct, because they are automatically identified from the pushover curve just before the strength loss.

See Also

• Bridge Seismic Sesign manual
• [Bridge seismic design request tutorial] - additional discussion for the model developed in the "Bridge Seismic Design" manual.
• [Caltrans hinge]