Seismic response and fragility analysis of BRB-retrofitted highway pile-slab structures with an improved load-transmission path

Pile–deck structures are emerging alternatives to conventional highway-widening methods, which have been increasingly applied in highway reconstruction projects under strict land-use constraints. However, the monolithic pile–deck connection renders such structures vulnerable to extreme disasters such as earthquakes due to the increased seismic force demands. Considering this, the current study proposes a new seismic resistant system for the highway Pile–deck structures, mainly comprising sliding mechanism between the deck and the piles, diagonally installed buckling restrained braces (BRBs) to generate an improved load-transmission path. Based on the established numerical models of the structures, nonlinear time history analysis is conducted to investigate the seismic responses of the proposed structures and their influential parameters. Furthermore, seismic fragility analysis is performed to demonstrate seismic vulnerability of the proposed Pile–deck structures. The results of the analyses indicate that by altering the transmission path of the inertia force from the deck to the piles, the seismic responses and probability of damage of the piles either above or under the ground can be significantly reduced. Compared to the prototype structure, the proposed structure experiences reductions of 98% and 55% in terms of the peak pile curvature and the peak deck displacement responses, respectively.