The Analysis In Load Test Of A Long-Span Continuous Bridge With Single Box Double Rooms Considering Lateral Effect

With the development of highway bridge,high-speed railway bridge and long-span bridge,bridge has become an indispensable part of the modern transportation system.With the increasing of the bridges and the development of new type of bridges,especially the wide bridges,the task of bridge inspection and maintenance in China is becoming more and more arduous.It is unavoidable for the bridges to be damaged by the effect of environment,natural disaster,long-term load and so on during the operation period,and bridge accidents often result in significant safety problems and property damage.In order to ensure bridges safety and normal use,it is very necessary to carry out the work of bridge inspection and maintenance strictly of new and in-service bridges.This paper took a long-span continuous bridge with single box double rooms as the backdrop,and the static load test program of the bridge was formulated considering lateral effect.Load test analysis was carried out on the maximum bending moment effect and maximum deflection effect of the side span L/4,side span L/2,pier top,mid-span L/4 and mid-span L/2 sections,and the lateral measuring points of section with single box double rooms were added.Then the load test results were processed and analyzed,the results show that the overall bridge deflection curve is smooth,and the variation law was also consistent with the force of the bridge structure under each load condition.Due to stress concentration and shear lag effects,the lateral distribution of the longitudinal strain of the roof and the bottom plate of box girder with single box double rooms is uneven,the strain at the load position and the web position is larger.After that,the entity model of the bridge was built by MIDAS,the large finite element software.Comparison analysis of deflection and stress strain under different load conditions were made.At the same time,the analysis of the eccentric load effect of the bridge and the factors to affect the shear lag effect of the wide box girder were carried out.The results show that the bending stiffness and longitudinal stiffness of the bridge met the design requirements.It was more reliable to calculate the eccentric load coefficient of the bridge by the finite element method.The larger the width span ratio and the width height ratio,the more obvious the shear lag effect.Finally,the load test method for large-span wide box girder bridge was established.It is necessary to build the entity model of the bridge and analyze the load test of the bridge for the wide box girder in the bridge load test considering lateral effect.And the bridgeshould not be simply analysed according to the elementary beam theory.The paper provides reference for the same kind of bridge load test work and future bridge research.