Study On The Transverse Connection Strengthening Of T-girder Bridge With Composite Truss

The transverse connection of the T-girder bridge plays a vital role in the overall stiffness,mechanical performance and stability of the bridge.With the increase of their ages in services,and the overload of vehicles during their operation,the transverse connections gradually decrease and even failure.Then,the bridges no longer work together as a whole,and even lead to the phenomenon of "single beam bearing".This adversely affects the normal operation of the T-girder bridges.In this paper,a series of investigations are carried out to study the structural characteristics and static characteristics of the multi-chip simply supported T-girder bridge.Then,a new type of transverse connection strengthening method is proposed for the T-girder bridge with concrete-filled steel tubular composite truss,and a variety of structural forms is designed and studied.By means of scale test and finite element simulation,the influence of different truss structures and layout methods on the mechanical characteristics and reinforcement effect of T-girder bridge is studied to compare and choose the best reinforcement scheme.The main contents and conclusions are as follows:(1)The strengthening test was carried out with nylon bridge model.Two structural forms of truss were adopted in the test,and three layout methods were adopted for reinforcement.The data of the test were processed,and the load transverse distribution under different working conditions were compared,so as to analyze the influence of different variables on the reinforcement effect.The results show that the increase of the number of strengthened trusses does have a positive effect on the improvement of the bridge’s mechanical performance,but the influence of the truss is gradually reduced with the increase of the number of trusses.For the two types of K-truss,The K-truss with complete bottom beam has better reinforcement effect than the K-truss with separate bottom beam.Under the same working condition,the maximum reduction rate of the peak value of the lateral distribution of the bridge model load is about 13%.(2)Finite element simulation of bridge scale test is carried out with ABAQUS software.The results show that the finite element calculation results are highly consistent with the experimental results.The stress characteristics of the test bridge model,including deflection and local deformation,can be accurately simulated.Therefore,the rationality of test design and the reliability of test data can be proved.In addition,similar to the scale experiment,the finite element simulation also shows that under various working conditions,the peak value of the lateral distribution curve of the load of the bridge can be significantly reduced by the two types of K-truss,and the stress situation of the bridge can be improved,which has relatively ideal reinforcement effect.(3)The finite element software ABAQUS was used to establish a 60 m three-span concrete T-girder bridge model,and the reinforcement effect of four types of composite truss structures was simulated and analyzed.The results show that under the same layout,the mechanical performance and reinforcement effect of the K-type composite truss are obviously better than that of the triangular composite truss.Under the same working condition and the same layout,the difference of reduction rate between the two composite trusses on the peak deflection of the bridge is generally 2%-3%.