| Since the orthotropic steel deck was invented in the fifty's of last century, due to its light weight, convenient erection and saving material, it is widely used. Numerous large span bridges which adopted orthotropic steel deck had been built. Nevertheless, the orthotropic steel deck with asphalt concrete pavement got diseases easily such as fatigue crack, rutting, longitudinal and horizontal crack of pavement. In order to solve the two main problems of orthotropic steel deck, the ultra-high-performance concrete was introduced by the author's team. It is used to constitute the light weight composite bridge deck system. At present, some researches already show that this kind of composite structure can effectively reduce the fatigue stress amplitude of fatigue details, and virtually eliminate the possibility of pavement crack.In this paper, the research object is composite bridge deck composed of orthotropic steel deck and 35 mm thin ultra-thin UHPC layer. Aiming at probing into the interfacial shear performance of light weight composite bridge deck system, the author has finished following researches:(1) In order to settle the problems of composite bridge deck system composed of orthotropic steel deck and 35 mm Ultra-high-performance concrete(UHPC) layer +20 mm pavement, which was that the UHPC layer is too thin to adopt conventional styles of shear connectors, an innovative shear connectors was proposed, which is named after Welded Rebar Mesh Shear Connectors(WRMSC).Through design and carry out the push-out tests, the ultimate shear bearing capacity and shear stiffness of 50 mm long welded rebar mesh shear connectors were measured. Besides, the load-slip curve of welded rebar mesh shear connectors was also got from the test results. At the same time, the whole process of push-out test was simulated by finite element analysis software. After the comparison of FEA results and test results, parameters analysis of welded rebar mesh shear connector was carried out. The test results show that the failure process of welded rebar mesh shear connectors is brittle failure. Deformation of the specimen is very tiny. The ultimate shear bearing capacity of 50 mm long welded rebar mesh shear connector is 119 k N; the elastic shear stiffness is 1838 k N/mm from the test results. The calculation results that the difference between transverse and longitudinal shear stiffness of welded rebar mesh shear connector is negligible, transversal shear bearing capacity is higher than that of longitudinal. With the decreasing of welding length, the gap between transverse and longitudinal shear bearing capacity diminished. Shear bearing capacity and stiffness is related to the length of itself and the diameter of longitudinal rebar, shear bearing capacity and stiffness decreased with the decrease of them.(2) Taking Runyang Yangtze bridge as the engineering background, the segmental finite element model of it has been established through sub-model technology, the effect of the different welding shear layout to the UHPC layer and the orthotropic steel was discoveried. The calculation results show that the shear connector arrangement has great effect on the ultra-thin UHPC layer, but little influence on every pat of steel structure. When the welding area in the unit area is constant, the smaller welding length that increase the shear connector layout density can reduce the bottom transverse and longitudinal stresses, the decreasing amplitude is up to 36%, thereby enhancing its durability, which should be considered during design. At the same time, increasing the layout density can also reduce the peak stress of steel beam, enhance the interface connection degree can improve the mechanical properties of the composite deck system. |
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