Numerical Study of Tsunami Force on Superstructure of Offshore Rigid Frame Box Girder Bridge

Offshore bridges need to bear complex wave and current loads and face the threat of extreme loads such as tsunamis. Potential tsunamis will have disastrous effects on coastal areas. Compared with conventional beam bridges, there are few studies on rigid frame box girder bridges. In this paper, based on a continuous rigid frame box girder bridge in the offshore area, the parameters of tsunami impact force are analyzed. First, based on Stoke theory and water level in the storage area, the water level in the static water area and quasi stable area in the dam break wave working conditions are obtained, and 12 kinds of dam break wave working conditions are preliminarily proposed to be used for the background bridge. Then, according to the determined simulation working conditions, the box girder dam break impact numerical model is simulated. According to the calculated results, the stress characteristics of the box girder under the tsunami impact are described in the way of time history stage division, and on this basis, The stress mechanism is analyzed from the whole level and local level. The results show that on the whole level, the variation of horizontal force and vertical force with time can correspond to the variation of dam break flow around the box girder. At the local level, the horizontal wall boundary bears the vertical force, the vertical wall boundary bears the horizontal force, and the inclined wall boundary bears both the horizontal force and the vertical force. In addition, negative pressure is the cause of suction on the wall boundary. It provides a reference for the calculation and analysis of tsunami load of offshore rigid frame box girder bridges, the identification of bridge failure modes and the formulation of protective measures.