This article is primarily written for CSiBridge, but a similar approach also applies to SAP2000.
Though influence-based moving-load analysis is a linear application, nonlinear step-by-step moving-load analysis may be performed by applying the Vehicle Live load pattern (or Bridge Live load pattern in SAP2000) in the Nonlinear Time-History load case.
This is accomplished through the process which follows:
- Define a load pattern of Vehicle Live type (or Bridge Live type in SAP2000). To avoid dynamic effects, use a minimal vehicle speed.
- Change the automatically created Multi-Step static load case to a Time-History load case. Select the Nonlinear, Direct-Integration analysis type, then define damping and other parameters as necessary.
- Run the analysis. When plotting results, choose the Envelope option.