Seismic Analysis Of High-Speed Railway Bridges Considering Track Constraint

With the rapid development of high-speed railway and wide laying of continuously welded rail, the influence of track constraint on high-speed railway bridges seismic performance is eager to solve. In addition, the track deformation and its safety limit value under seismic action is also worth further study. In this paper, based on the integrated model of beam and rail interaction under seismic action, the anti-seismic behavior of high speed railway bridges considering track constraints and the deformation of track on bridge are studied systematically. The main works are as follows:(1) Based on the theory of interaction between beam and track and considering the nonlinearity of bridge piers, beam-track interaction model is established. In the model, the longitudinal resistance of the line, which is simulated by the nonlinear spring, chooses to use the ideal elastic plastic model, and main beam is simulated by beam element with steel arm. And the correctness of the model is verified by comparing with the relevant literatures.(2) Taking two common types of bridges in high speed railway (the multi span simply supported and simply supported +continuous+simply supported bridge) as examples, the seismic response of the bridge under consideration and without consideration of the track constraint is compared. The results show that the frequency of structure increases and the displacement of pier top decreases with the consideration of track constraints, both of which are helpful to anti-seismic of bridge. And whether the track strength meets the requirement or not under earthquake action is checked. The results indicate that the damage of line may precede the bridge, and the stress checking calculation of the rail under earthquake action should be added.(3) The influence of parameters such as the length of the subgrade, the number of spans of simple supported beam, the longitudinal resistance of the line and the span of simply supported beam on the seismic response of the beam and track system is analyzed.(4) Taking the 5 span simple supported beam as an example, the track deformation under the 7 degree,8 degree and 9 degree frequent earthquake and the design earthquake is studied. The track angles of each beam joint are calculated and the safety of the track angles is evaluated combined with the corresponding norm. The influence of the pie stiffness and the lateral stiffness of the fastener on the track angle is analyzed. The results show that large difference of pier stiffness should be avoided in bridge design in order to avoid too large track angle.