Analysis Of Mechanical Properties Of Prefabricated Small Box Girder Bridges

The prefabricated assembly bridge structure can not only accelerate the construction speed and improve the construction quality,but also reduce environmental pollution and reduce the consumption of carbon.Assembling a small box girder bridge is an important part of the transportation construction industry to promote the assembly of standardized green buildings.However,whether the static and dynamic performance of the assembled small box girder bridge meets the requirements for the use of the bridge is an urgent problem to be studied.This project aims at the actual project and analyzes the static performance of a single small box beam and the static and dynamic performance of an assembled small box girder bridge through field tests and finite element simulations;the main research methods and conclusions are as follows:(1)The static load test,finite element analysis and theoretical calculation of the load capacity of a single small box girder were performed respectively.The deflection and strain of the small box girder under different load conditions were analyzed.The results show that under the uniform load,the deformation law of the deflection point of the symmetrical cross-section control point of the small box girder is the same,which satisfies the deflection curve equation The finite element calculated value is consistent with the change curve of the actual measured value and the calculation result is close.The finite element model can be used to analyze the mechanical properties of its small box girder structure.(2)For the assembly of small box girder bridges,the partial load test of a static load vehicle is carried out to study the displacement and strain values of the crosssection bottom cross section of small box girders under different vehicle load conditions.The research shows that in the partial load test of the vehicle,under the same load condition,the measurement point of the control section is gradually reduced in deflection and strain along the direction of loading the vehicle's distal end.Under different load conditions,the same point is increased with the load.The deflection and strain also increased,indicating that the assembly of small box girder bridges is better overall.(3)Through the dynamic test of assembling small box girder bridges,the dynamic characteristics of the assembled small box girder bridges are studied.The results show that the measured fundamental frequency of the assembled small box girder bridge is greater than the calculation of the fundamental frequency;the damping ratio is 0.045;the overall strength and stiffness of the bridge meet the requirements.(4)Midas Civil finite element software was used to study the reasonable modeling method for the assembly of small box girder bridges.The study shows that the use of beam element load loading and surface element load loading have almost no effect on the calculation results.Using a beam element model with a virtual beam,the beam structure of the upper part of the bridge is clearly defined,and the calculation of lateral and longitudinal internal forces is clear.The result is highly reliable,but the modeling takes a long time.Without the beam element model of the virtual beam,the beam structure of the upper structure of the bridge is divided clearly,and the calculation of lateral and longitudinal internal forces is convenient,but the error of the calculation result is large,which should not be adopted during the modeling process.The simplified model of the beam element model is used.The workload is small and the calculation result is reliable.It is the preferred method for the modeling of assembled small box girder bridges.