Research On Influencing Factors Of Seismic Behavior Of Continuous Rigid Frame Bridge Considering Pile-soil Interaction

With the rapid development of the traffic industry,the pre-stressed concrete continuous rigid frame bridge has been widely used in domestic as of the advantages of good integrity,material consumption and better adaptability to the displacement caused by shrinkage and creep of concrete and temperature change.For long-span pre-stressed concrete continuous rigid-frame bridge,it is of great practical significance to study how to improve its seismic performance and reduce the damage in large earthquakes,especially for the short continuous rigid frame bridge in soft soil site,because of the weak confinement of pile foundation and the large free-length calculation of pile foundation,the importance of considering the common action of pile-soil in the seismic performance analysis is discussed It is also a topic that needs to be focused on in continuous rigid frame bridge research.Based on the engineering background of a pre-stressed concrete continuous rigid frame bridge in a certain place,on the basis of considering the pile-soil interaction,the dynamic characteristics,the anti-seismic performance and the influencing factors of the pre-stressed reinforced concrete continuous rigid frame bridge are studied,and the main work and conclusions are as follows:1)Taking the actual project as the background,the finite element model(basic model)of pre-stressed concrete continuous rigid frame bridge was established by using midas / civil considering the interaction between pile and soil.On this basis,the dynamic characteristics of the bridge and its influencing factors are studied.The results show that it is necessary to consider the effect of pile-soil interaction on the dynamic characteristics of the bridge,and the change of the pier height has the greatest influence on the dynamic characteristics of the bridge.The longitudinal stiffness,pile diameter and pile spacing of the abutment bearing can only change the bridge The dynamic characteristics of certain directions have a certain impact,and the piers section hollow or solid on the structural dynamic characteristics of little impact from the perspective of seismic design to meet the carrying capacity of the premise,the use of hollow pier may be more advantages.The results show that the influence of considering the dynamic characteristics of pile-soil interaction of bridge is necessary,and the high pier change the maximum influence on the dynamic properties of the whole bridge abutment,bearing longitudinal stiffness,pile diameter and pile spacing on the bridge direction change only some dynamic characteristics have an impact,and the hollow or solid pier the dynamic characteristics of the structure has little effect.2)The seismic behavior of the basic model is analyzed by using response spectrum analysis and time history analysis respectively.The results show that the displacement response of the structure considering the interaction of pile and soil is obviously larger,and both methods of seismic response analysis can provide the basis for the seismic design of bridges.However,the analysis results of time history analysis method are more intuitive and abundant,and more conservative results are obtained in most cases of longitudinal seismic response analysis of bridges.Therefore,the subsequent analysis of influencing factors is carried out by time-history analysis.3)Dynamic time history method is used to study the influence of pile diameter,pile spacing,pier height and longitudinal stiffness of abutment support on the seismic performance of bridge,The results shows that: the lower part of the structure design of continuous rigid frame bridge can suitably increase the height of pier,can reduce the stiffness,the maximum internal force decreases,is conducive to the aseismic structure;for selection of edge piers to avoid vertical restraints stiffness of foundation design;In the foundation design,the pile diameter and the spacing of the continuous rigid frame bridge can be reduced as much as possible under the condition of satisfying the bearing capacity and the relevant requirements of the norms.