Stochastic seismic analysis of a concrete-filled steel tubular (CFST) arch bridge under tridirectional multiple excitations

• A scheme in modelling tridirectional spatial ground motions at varying site conditions is derived.
• A site response approach for tridirectional motions is presented.
• FE model updating can be used to serve, benefit, and promote structural seismic analysis.
• Stochastic seismic analysis of a CFST arch bridge under tridirectional multiple excitations is conducted.
• Recommendations for actual design of arch bridge under tridirectional multiple excitations are drawn.

This paper presents a comprehensive theoretical analysis of a concrete-filled steel tubular (CFST) arch bridge under tridirectional spatial seismic motions using the pseudo-excitation method. Formulations for modelling tridirectional spatial ground motions at varying site conditions are first derived. A site response analysis is presented for the tridirectional motions based on deterministic wave propagation theory, assuming that the base rock motions consist of out-of-plane SH wave or in-plane combined P and SV waves propagating into the multiple layered site with an assumed incident angle. Integration between the structural health monitoring (SHM) technique and the structural seismic analysis is proposed and conducted for the finite element (FE) model calibration of the CFST arch bridge through the model updating approach. Using the calibrated FE model, stochastic seismic analysis of the CFST arch bridge is conducted in a comprehensive and systematic way, by considering the dimensionality, incoherence effect, wave-path effect of ground motions, and local site effects with different and irregular site conditions. Critical conclusions are drawn and can be applied in the actual seismic design of the half-through CFST arch bridges under tridirectional multiple excitations.