Study On The Seismic Performance Of The Lock-up Devices With Continuous Beam Bridges Under Elastic-plastic State

With the progression of technology and the capacity of calculation,for continuous beam bridge,the number of piers and the length of total span become larger,such situation may cause challenges for continuous beam bridge seismic design.Since the fixed pier mainly bears the inertia force caused by the upper structures of continuous beam bridge,the concentration of bending moment and shear force is unfavorable to the seismic performance of the whole bridge.Lock-up devices are capable of redistributing the loading pass of inertia force,and as an earthquake resistant device have accomplished certain effect.Most of the precedent researches focus on the effectiveness of Lock-up device when the continuous bridges are within elastic state,however,with the widening acceptance of the PBSD(performance-based seismic design),taking the plastic behavior of bridge is certainly necessary.Based on the precedent researches,this paper mainly studies on the effect on the seismic performance of bridge caused by the Lock-up device when the bridges are into plastic state,the main research content is as follows:(1)Consulting the related literature and data,comprehensively analysis the history of Lock-up device and the research status in bridge seismic engineering.According to the mechanism of the Lock-up device,compare different methods of modeling the Lock-up device,and point out that using the Maxwell viscoelastic model to modeling the Lock-up device is more accordant to engineering practices.(2)Summarize the principal theories of bridge seismic design and the methods of bridge seismic response calculation.Using the finite software SAP2000 to establishes the continuous beam bridge model with the consideration about plastic behavior.Study the seismic performance of the Lock-up device when the bridges are within elastic state by the IDA(incremental dynamic analysis),and discuss the effect on the seismic performance of the Lock-up device caused by the difference of properties of ground motion and the high height of piers.(3)Study the seismic performance of the Lock-up device when the continuous beam bridges are into plastic state by nonlinear time history dynamic analysis.Discuss the effects on state of force and seismic performance of bridge caused by the difference of the distribution and the number of plastic hinges triggered by the utilization of the Lock-up device.(4)Study the seismic performance of the Lock-up device under long-period seismic wave.Compare and analyze the displacement response,velocity response,displacement seismic-reduction rate and velocity seismic-reduction of the continuous beam bridges with Lock-up device,respectively under the long-period seismic waves and short-period seismic wave.Discuss the influence on the internal force redistribution of continuous beam bridge caused by the Lock-up device under long-period seismic wave.