Engineers at BSI are working to enhance extant time-history seismic response analysis features. These efforts include adding the ability to apply unique acceleration-time histories to substructure node(s), and computation of the system response. At the discretion of the bridge engineer, identical acceleration-time histories can be applied to all nodal points (e.g., base excitation), or alternatively, unique acceleration excitations can be assigned to selected nodal degrees of freedom for any number of embedded nodes. In this latter case, acceleration-time histories may be pre-computed using external software, obtained by site-specific measurements, or through physical model testing. Within FB-MultiPier, bridge engineers have access to two loading options: “Applied Acceleration vs Time” and “Applied Acceleration vs Time (All nodes),” which can be accessed from within the “Dynamics” page of the “Model Data” window. Bridge model nodal response in the form of acceleration, velocity, and displacement time histories can be defined for up to 25 nodal points.
Complimentary to the enhancements for time-history seismic response analysis are features specific to dynamic soil-structure interaction modeling. Engineers at BSI are building validation model sets, which consist of comparing results obtained from FB-MultiPier to measurements from physical testing (e.g., lateral Statnamic tests). With these enhancements, dynamic soil-structure interaction phenomena such as rate-dependent response, soil gapping, soil degradation, and various forms of damping can be incorporated into bridge and substructure time-history models.