Effect Of Different Limit Devices On Transverse Seismic Performance Of Medium And Small Span Girder Bridges

Among the domestic medium and small span beam bridge structure,the application of plate rubber bearings is widely used.In order to limit the transverse displacement of the main beam under earthquake action,reinforced concrete shear key are usually arranged on both sides of the cover beam as the limit device.It constitutes the seismic system of the superstructure.The horizontal damage forms of such bridges in earthquakes mainly include: the shear key damage,bearing failure,beam falling and pier failure,especially beam falling and pier failure,which will lead to the complete failure of the bridge.Two limiting devices,wedge block and viscous damper,are proposed to improve the transverse seismic performance of medium and small span bridges.In this paper,on the basis of relevant research results at home and abroad,a common 3×20m continuous concrete beam bridge is taken as an example,and the Open Sees finite element software is used to establish the calculation model,respectively analyzing the influence of two limit devices,wedge block and viscous damper,on the transverse seismic performance of medium and small span beam bridges.The main research contents and conclusions are as follows:(1)The finite element software was used to establish the bridge space calculation model using the wedge block,according to the example site type,four ground motion records were selected to analyze the time history of the model.By changing the friction coefficient of the plate rubber bearing,the influence of different friction coefficients on the displacement response of medium and small span bridge is analyzed.The transverse seismic response characteristics of the structure with flexible shear key,rigid shear key and wedge block are compared and analyzed.When the rigid shear key and wedge block are set,the seismic response of the structure is not sensitive to the change of friction coefficient of the bearing.(2)The influence of the wedge block on the transverse seismic performance of the bridge under different parameters is analyzed,and the rationality of the wedge block is further verified.The calculation results show that the wedge block can effectively reduce the seismic response of the structure and improve the seismic performance under the appropriate parameters.(3)The finite element model of small and medium-span bridges with additional viscous dampers is established.The frictional slip effect of plate rubber bearings,the nonlinearity of reinforced concrete shear key,the mechanical properties of viscous dampers and the elastic-plasticity of reinforced concrete piers are considered.And other factors.The displacement response of the top of the pier and the relative displacement response of the pier are introduced as indicators.The transverse seismic behavior of the additional viscous damper bridge and the conventional system bridge are compared and analyzed.The bearings,shear key and viscous dampers are studied in the earthquake.The hysteretic behavior under the action shows that the additional viscous damper can effectively improve the transverse seismic performance of the bridge.(4)The influence of the damping coefficient C of the viscous damper and the damping index α on the structural response is investigated.Studies have shown that when different parameters are used,the response of the structure is significantly different.