| With the rapid development of urban three-dimensional transportation system,people have further requirements for the structural form and function of bridges.Steel-concrete composite curved box girder bridge inherits many advantages of steel-concrete composite girder bridge,meets the requirements of urban bridges for function and beauty,overcomes the construction inconvenience caused by terrain and building obstruction in the construction process,and also conforms to the concept of green development.It is increasingly used in engineering,but its static performance and seismic response research can not keep up with the development of engineering practice.Therefore,taking a four span steel-concrete composite curved box girder bridge as the research object,the corresponding models are established respectively based on the finite element software Midas/Civil and SAP2000 to study the static performance and seismic response of the girder bridge,in order to provide a certain reference basis for the design and construction of the girder bridge.The main work contents are as follows:（1）Based on Midas/Civil,the analysis model is established to simulate and calculate the construction stage and operation stage respectively.During the analysis of the construction stage,five construction stages are designed to simulate the whole construction process of the beam bridge.The deflection deformation of the beam bridge and the stress state of the concrete deck and steel box girder are compared and analyzed.It is found that the stiffness and stress of the beam bridge meet the requirements of the specification;In the analysis process of operation stage,in order to explore the influence of concrete shrinkage and creep and vehicle load on the beam bridge,three load combination conditions are adopted to analyze the influence of bearing reaction,vertical displacement of bridge deck and structural stress respectively.It is found that concrete shrinkage and creep has little influence on bearing reaction and structural stress,but has a great influence on vertical displacement of bridge deck.The vehicle load has a great influence on the bearing reaction,the vertical displacement of bridge deck and the structural stress.（2）The analysis model is established based on SAP2000 to explore its dynamic characteristics and the most unfavorable input direction,as well as the seismic response under the action of response spectrum and time history analysis.In the process of dynamic characteristic analysis,it is found that the beam bridge has sufficient stiffness,and the transverse stiffness of the beam bridge is smaller than that along the bridge;In the process of determining the most unfavorable input direction value,the response spectrum analysis method is used.It is found that the seismic response value of the pier is quite different under the multi-directional input of the response spectrum.Compared with the seismic response peak value of the pier,the most unfavorable input direction is160°;In the process of response spectrum analysis,the seismic responses along the bridge direction,across the bridge direction and the most unfavorable input direction under the response spectrum are analyzed.It is found that the pier top displacement,pier bottom bending moment and shear force in the transverse direction are larger than those in the longitudinal direction,while the axial force at the pier bottom is smaller than that in the longitudinal direction.At the same time,it is found that if only the seismic response along and across the bridge is analyzed,the displacement and internal force response will often be underestimated.Determining the seismic response through the most unfavorable input direction can avoid the underestimated pier displacement and internal force response in seismic design;In the process of dynamic time history analysis,three seismic waves are input along and across the bridge,the maximum values of pier displacement and internal force response are obtained,and the corresponding time history curves are drawn.It is found that the beam bridge has good seismic performance.（3）Based on SAP2000 finite element software,the variable parameter models with radius of curvature of 100 m,180m and 260 m and the variable parameter models with pier height of 10 m,15m and 20 m are established to analyze the seismic response parameters of the beam bridge,including the impact on the dynamic characteristics,the most unfavorable input direction and the impact on the dynamic response.When changing the curvature radius and pier height of the model to study the influence on the dynamic characteristics,it is found that the structural natural vibration period of the first four modes decreases with the increase of the curvature radius,the curvature radius has little influence on the structural natural vibration period after the fifth mode,and the curvature radius has little influence on the vibration mode characteristics of the first four modes.The natural vibration period of the structure increases with the increase of pier height,and the pier height has a great influence on the vibration mode characteristics of the first four modes.（4）When changing the radius of curvature and pier height of the model to study the impact on the most unfavorable input direction,the response spectrum analysis method is used.It is found that with the continuous increase of the radius of curvature,the most unfavorable input direction gradually tends to be stable.When the radius of curvature is small,there is a sudden change in the most unfavorable input direction.The influence of pier height on the most unfavorable input direction is small and can be ignored.（5）The influence of the curvature radius and pier height of the model on the dynamic response of the beam bridge is studied.The response spectrum analysis method is used to study the influence of pier top displacement and pier bottom internal force under the excitation along and across the bridge.It is found that there is a great difference in the dynamic response of along bridge and cross bridge excitation.The increase of curvature radius and pier height has a great impact on pier top displacement,pier bottom shear force,pier bottom bending moment and pier torque.Figure [90];table [25];reference [69]... |
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