Studies On The Failure Mechanism Of The Composite Structure Of Concrete Box Girder Widened By Steel Cantilevers

In recent years, bridge widening projects are springing up. The structure of box girder widened by steel cantilevers is a new kind of steel-concrete composite structure. Its failure mechanism is not yet clear. Combining with experiment and numerical simulation, the failure mechanism of the composite structure of concrete box girder widened by steel cantilevers is investigated. The main contents of this paper are as follows:(1) This article details the bridge widening methods, at home and abroad and has a comparison with their applicability. The feasibility、research status and key problems of Steel Cantilever Widening Concrete Box Girder Method are mainly stated.(2) Study the basic principle of smeared cracking model and damaged plasticity model and their mechanical behavior under different stress states in ABAQUS have been researched. Then compare the simulation results with Kupfer Test’s and verify the precision of simulation. At last, make a comparison between the two models and make a summing up of their applicable cases. The constitutive model of concrete post-cast diaphragm was determined.(3) Research the bond mechanism between bolt and concrete、the influential factors concerned on the sticking strength、the characteristics of the bonding effect and the bond-slip relationship. Build pull-out test model to simulate using XuYoulin constitution in ABAQUS software. Then make a comparison between the simulation results and GaoXiangling Test’s to confirm the feasibility and validity of simulation.(4)Making widening model test specimen to experiment with model static monotonic loading destruction test. Build finite element model to simulate in ABAQUS software. Then make a comparison between the simulation results and model test’s to confirm the validity of simulation. Carry out multiple factors numerical simulation. In various parameters, observes the failure mode、destabilizing processes and the trends of stress、strain of model key parts. Sum up the influence rules of the parameters on the failure mode. Summarize the influence factors concerning the ultimate bearing capacity of widened structure to reveal its failure mechanism.