Vulnerability assessment of coastal bridge superstructure with box girder under solitary wave forces through experimental study

Abstract

This study presented a vulnerability assessment of a selected coastal bridge located at Haitan Strait on the east China sea through experimental study. The extreme wave is simulated using the solitary wave that generated by piston-type wave maker in a medium-sized wave-flow flume at Southwest Jiaotong University's Deep-Water Long-span Bridge Laboratory. Horizontal and vertical wave forces acting on the deck with a box girder due to solitary wave are measured through laboratory experiments. Seventy-five cases included three water depths, five wave heights, and five submergence coefficients are conducted in the experiment. Although there is plenty of work addressing the extreme wave forces on the coastal bridge's superstructures, the experimental study that focuses on the vulnerability assessment of coastal bridge superstructures subjected to extreme wave forces, especially for the box girder geometry, are absent. Combined with the experimental data and snapshots, the effects of non-dimensional wave heights and submergence coefficients on wave forces are discussed in detail. The structural capacity is determined according to the structural parameters of the approach span of the selected prototype coastal bridges. In addition, the dominant structural failure modes of the simply support superstructures are assumed to be uplift and lateral displacement. The vulnerability assessment of the given coastal bridge superstructure is accessed by comparing wave forces with superstructure's capacities. The results indicate that: 1) compared to the submerged condition, the elevated superstructure suffers larger horizontal and vertical wave forces; 2) the impulsive wave force plays an important role in the vertical wave force on the deck with a box girder, especially for the high-elevated superstructure; 3) the failure probability of coastal bridge superstructure subjected to extreme wave conditions will be effectively reduced by increasing the elevation height of the superstructure. This study provides a further understanding of the fragility of the box-type superstructure under the extreme disaster.