Experimental research on adjacent pounding effect of midspan curved bridge with longitudinal slope

Abstract

Seismic pounding between adjacent girders has a significant effect on the seismic performance of midspan bridges, and connection parameters, such as gap size and longitudinal slope, influence adjacent pounding (AP). However, at present, such influence of the aforementioned parameters on pounding between adjacent girders is unclear, and relevant experimental tests remain insufficient. For these reasons, a 1/10-scale curved bridge model with a small radius and a longitudinal slope is designed and fabricated; moreover, an adjustable simulation method of the pounding between adjacent girders is proposed. A series of shake table tests is conducted to analyse the influence law of the AP parameters, including the excitation direction and gap size; the AP effects on the dynamic response of the bridge model with a longitudinal slope and the simulation of adjacent bridges are also analysed. The experimental results show that pounding responses between adjacent girders are significantly influenced by the state of excitation waves, and the peak pounding forces under bidirectional excitation are significantly greater than those under the unidirectional excitation. The outside peak pounding force is greater than that on the inside because of the bending–torsion coupling of the curved bridge model; this aggravates the rotational response of the model. The pounding frequency decreases with the increase in gap size, whereas the peak pounding force is inconsistent with the change in gap size; large gaps may also induce large pounding forces. The pounding force near the short pier can be greater than that near the tall pier because of the influence of longitudinal slope. The foregoing is also the major reason for the significant vertical dynamic response of the girder; the pounding causes large horizontal and vertical acceleration pulses at the ends of the main girder. The displacement response of the pier top will significantly increase after the AP, and the pounding effect will increase the damage probability of piers; hence, these should be considered in the seismic design of adjacent midspan curved bridges. The proposed AP simulation method between adjacent midspan curved bridges can be used to investigate the AP effect on adjacent midspan bridges.