Seismic Pounding and Protection Measures of Simply-Supported Beams Considering Interaction between Continuously Welded Rail and Bridge

Abstract

The pounding effect between neighboring simply-supported beams can damage a bridge and even cause collapse of a beam. However, previous pounding studies did not consider the influence of the continuously welded rail (CWR) during earthquakes, thus overestimating the seismic response of the railway bridge, yielding uneconomic design and neglecting the influence of seismic pounding on track forces. Therefore, the main focus of this paper is to investigate the influence of CWR on bridge pounding through numerical modeling. In the simulation, nonlinear bar element was used to model longitudinal resistance of the track. Large-mass method was used to obtain multi-support excitation and the Kelvin model was applied to simulate the beam pounding. In addition, a number of detailed effects were taken into account, including the nonlinear behavior of the bearing, the moment–curvature relationship of the pier and the interaction of the piles and soil. Taking the three-span 32 m simply-supported box beams on the Shanghai–Kunming line as an example, this paper also studies the influence of temperature loads, train braking load, traveling wave effect, line resistance, track expansion device, buffer device and beam connection device on the bridge pounding effect an d the pier force. The numerical results showed that the track can significantly mitigate the pounding effect of the bridge. The traveling wave effect could significantly increase the force in track and bridge, which can result in pounding. If the high-speed railway train brakes on the bridge during an earthquake, the rail may be destroyed near the location of abutment. The use of track expansion devices and small resistance fasteners could result in the poundi ng effect between the neighboring beams while the use of buffer device and beam connection device can mitigate the pounding effect and eventually reduce force on the pier.