Trial Design And Research On Mechanical Behaviors Of Integral Abutment Curved Bridge

The integral abutment bridge eliminates expansion joints and telescopic devices,improves the durability of the bridge and reduces the maintenance cost in the later period,it is a new type of bridge with broad application prospects.Curved bridges are inevitably used due to factors such as topography,and the number of curved bridges has increased dramatically over the past few decades.At the same time,the temperature deformation of the curved bridge end is smaller than that of the straight bridge end,which is more suitable for building bridges without expansion joints.However,in the many studies on monolithic abutment bridges,most of them are mainly straight bridges,and there are few studies on curved bridges.And due to the "bending-torsion coupling effect" of the curved bridge and the mechanical characteristics of the "structure-soil interaction" in the integral abutment structure,the force performance is very complicated.This makes the design and construction of the integral abutment curved bridge more difficult,and the design methods and experience that can be used for reference are extremely scarce.In view of this,this paper relies on a high-speed ramp in Fujian Province as the engineering,and carries out the transformation and makes the ramp without expansion joints(integral abutment),systematically researching the mechanical performance of the integral abutment curved beam bridge.The details are as follows:(1)Introduce the research and application status of integral abutment bridges at home and abroad and the commonly used integrated abutment bridge calculation model,and analyze the simulation method and calculation model of structure-soil interaction.(2)The MIDAS/CIVIL 2015 finite element software was used to establish the 3D finite element analysis model of the original bridge and the integrated abutment curved bridge considering the platform-soil and pile-soil interaction.The accuracy of the finite element analysis model is verified by comparing the measured data of the static load test of the real bridge with the model calculation results.The structural safety check of the integral abutment curved bridge is designed.The results show that the upper main beam structure of the integral abutment curved bridge can be initially designed according to the parameters of the corresponding span continuous beam bridge,and then the section crack resistance performance is improved by tensioning the prestressed steel bundle to meet the engineering design requirements.(3)Contrasting and analyzing the bearing performance of the original bridge and the trial design curved bridge under the combined load of dead load,vehicle load,temperature,concrete shrinkage,earthquake and other combined load conditions.The results show that the integral curved bridge has better mechanical performance than the original bridge,and the seismic performance of the integral abutment curved bridge is obviously better than that of the original bridge,which can effectively avoid the lateral deflection of the main beam in the earthquake.The phenomenon of position and falling beam is more advantageous in the use of high earthquake areas.(4)Select the difference of positive and negative temperature,pile side soil type(value of m),pile length,pile diameter,abutment height and main beam curvature radius as parameters,and carry out the analyze of parameter sensitivity of the mechanical behavior and deformation characteristics of the integral abutment curved bridge structure.The results show that the curvature radius has a significant effect on the mechanical behavior and deformation of the integral abutment curved bridge,which is an important parameter affecting the mechanical performance of the integral abutment curved bridge.The most sensitive to the change in radius of curvature is the radial displacement of the mid-span section of the main beam.When the radius of curvature is ≥150m and decreases continuously,the radial displacement of the main beam span increases rapidly.However,as the radius of the main beam continues to decrease,the radial displacement begins to decrease.