Deformation and stress characteristics of simply supported beam bridges crossing fault under reverse fault dislocation

To investigate the deformation patterns and failure mechanisms of simply supported beam bridges crossing faults subjected to reverse fault dislocation, a 1:16-scale bridge model was designed based on a national highway section in western China. Utilizing a Large Normal Gravity Strong Earthquake Ground Rupture Model Device, model experiments were conducted to analyze the deformation and stress characteristics of these bridges under reverse fault dislocation. Complementing the physical modeling, a finite element model incorporating concrete damage plasticity was developed to examine the damage characteristics of the prototype bridge under reverse fault dislocation. Experimental results indicated that reverse fault dislocation induces multiple deformation phenomena in simply supported beam bridges crossing faults, including: (1) beam displacement and inclination, (2) bearing misalignment, (3) pier inclination, and (4) beam drop failure with increased fault dislocation, ultimately leading to complete bridge collapse. Numerical simulations revealed that the damage characteristics of simply supported beam bridges over reverse faults manifest as: (1) tensile damage primarily resulting from beam displacement-induced collision and compression and (2) tensile damage occurring mainly at four critical locations—pier foundations, beam bottoms, abutment breast walls, and back walls. The data and conclusions obtained from the model experiments and numerical simulations can provide critical references for the seismic design and construction of bridges crossing active faults in seismically complex regions of western China, especially in multi-fault systems such as those in Xinjiang, China.