Experimental Study And Theory Analysis Of Steel-Concrete Composite Bridge Deck With PBL Connectors

Bridge deck is an important part of bridge structure, the working state of which will directly affect the bridge performance in service stage. Steel-concrete composite bridge deck is a new kind of composite member that depends on shear connectors, such as studs and perfobond ribs (usually abbreviated as PBL), to make steel plate and reinforcement concrete slab worked together. This composite deck can effectively achieve the design and application of long span bridge deck to take advantage of the tensile properties of steel plate and compressive properties of concrete slab under load. However, the study on composite deck has just begun and the theoretical system is still not completed. Combining theoretic analysis, experimental research, and numerical simulation, the author carries out special research on steel-concrete composite bridge deck with PBL connectors. This dissertation mainly includes five parts:In the first part, on the basis of reading a large number of domestic and foreign literatures, the overviews of steel-concrete composite slabs and shear connectors are undertaken, and the research shortcomings in this field are found. Then, a project to study the behaviors of steel-concrete composite bridge deck with PBL connectors is put forward.In the second part, two types of experiments were completed. The first is the experiment on one-way composite deck. Fourteen specimens were designed and tested under positive and negative moment. The main parameters include arrangement form of PBL connectors, thickness of composite deck, and reinforcement ratio. The second is the experiment on two-way composite deck. Seventeen specimens were designed and tested under forward and reverse concentrated load. The main parameters include thickness of steel plate, spacing of PBL connectors, and constraint condition. During the experimental process, the failure mode and deformation behavior of composite deck, steel and concrete strain, relative slip between steel plate and concrete, cracking behavior and development, and ultimate bearing capacity were studied. The test results show that most one-way composite deck specimens failed in typical bending mode and individual specimens failed in vertical shearing mode or longitudinal shear mode; most two-way specimens failed in flexure-punching mode and individual specimens failed in shearing mode. Steel plate reached its yield stress in most specimens in final loading stage, but the ultimate load-carrying capacity did not decrease obviously, which exhibited good ductility.In the third part, a3D finite element model using FEM software ABAQUS was established for analyzing the behavior of steel-concrete composite bridge deck with PBL connectors on the basis of considering the material nonlinear and contact nonlinear. The experiment data accorded with the calculate result well, so the FEM could be a powerful supplement for the experiment.In the fourth part, with reference to the experiment research and the relevant provisions in the design specifications, the theoretical analysis of composite deck’s mechanics behavior was carried out. The calculation method of composite deck’s cracking moment was established by taking into account the concrete plastic deformation in tensile area under positive and negative moment, and the calculation formula of plastic influence coefficient and cracking moment was derived. Based on the simplified plastic theory, a theoretical formula was proposed for the bearing capacity of normal section of this new type composite deck. At last, the practical formulas of flexural rigidity and crack width which satisfied engineering design were proposed.In the fifth part, linear distribution model, triangle distribution model, and sector distribution model based on yield line theory were adopted to calculate the ultimate bearing capacity of two-way composite deck respectively. Based on the failure characteristics of two-way specimens, a new flexure-punching failure mode was proposed. By discounting the flexural capacity in yield line theory, simplifying the punching capacity in plastic theory, and adding them up, the calculation method for the ultimate bearing capacity of two-way composite deck was obtained.Above-mentioned research results can provide references for engineering application and further study of steel-concrete composite bridge deck with PBL connectors.