Shaking Table Research Of Long Span Continuous Rigid Frame Bridge

The continuous rigid frame bridge combines the advantages of T type rigid frame bridge and continuous girder bridge,characterized by continuous girder girder and consolidation with piers.The continuous rigid frame bridge has become the first choice for long-span prestressed concrete bridges.The long-span continuous rigid frame bridges have complex forces under the earthquake action,and there are many kinds of coupling effects.The large span continuous rigid frame bridge is often not uniformly excited,but a multi point excitation,which will be influenced by the factors such as the traveling wave effect,the site effect and the coherence effect.The amplitude and phase of the input seismic waves at each point of the large span continuous rigid frame bridge are generally different,only considering single point analysis or uniform excitation.The seismic design of the bridge can not be improved substantially.Therefore,the effect of multi point excitation and multidimensional seismic coupling must be considered for the long span continuous rigid frame bridge.In order to study the seismic response characteristics of long-span continuous rigid frame bridge,taking a high pier and long span continuous girder bridge as the research object,the bridge span is large and the load is complex.In order to study the seismic performance of the bridge,theoretical calculation is a necessary condition,and the shaking table model test of the structure should also be carried out.The theoretical guidance of this paper is the dynamic similitude theory.For the model structure,C40 concrete and Q235 steel are used as raw materials to make a test model with a scale of 1/20.In order to study the seismic performance of the bridge,a shaking table shaking table test was carried out.The dynamic response characteristics of the scale model are measured through experiments,including the dynamic response of acceleration,displacement and strain.The accurate fiber model of each section of the structure model is established by using the finite element simulation software Opensees,and the program of uniform excitation and multipoint excitation is written in TCL language,and the theoretical calculation model is established to calculate the dynamic characteristics of the model.The correctness of the theoretical calculation model is verified by the comparison between the theoretical calculation and the measured values.In order to ensure the accuracy of the test data,the finite element simulation software Midas/Civil is used to establish the model,which provides a reference for the calculation of theoretical calculation results.Using the SeismoMatch software and the SGS plug-in in the MIDAS/CIVIL to synthesize artificial seismic waves,design seismic waves in a variety of working conditions and design test conditions.The local site effect,traveling wave effect and local field effect and traveling wave effect of the acquisition structure in the uniform excitation and multi point excitation conditions,as well as the local site effect and traveling wave effect in the comprehensive and non consistent earthquake conditions.Under the action of acceleration,displacement and strain data of structural response,the influence of multi point excitat ion on structural response is studied.The study shows that the greater the earthquake intensity,the greater the structure response,the greater the intensity of the input seismic intensity,the greater the structure response,and the nonlinear relationship between the seismic intensity and the structural seismic response;the site type is the structure of the structure.The seismic response has a certain influence,and the local site effect has a weak influence on the structural response.In a certain range,the smaller the velocity of the traveling wave effect,the greater the influence on the structural response,the greater the amplitude of the response of the structure,and the effect of the traveling wave effect on the seismic response of the continuous rigid frame bridge with high piers and large span.Favorable,with the increase of wave velocity,the response amplitude of the structure becomes smaller and smaller.When the wave velocity is greater than 500m/s,the traveling wave effect is not obviou s.When the traveling wave effect and the local site effect are present,the response of the structure is far less than the response of the uniform excitation to the structure.