Study On Cracking Behavior Of Fiber-reinforced Concrete Bridge Deck

In recent years,steel-concrete composite beams have been widely used in highway bridge construction in China,but the early cracks of concrete bridge slabs during construction and operation period directly affect the durability and operation reliability of Bridges.In order to solve this problem,one of the measures commonly adopted at present is to enhance the crack resistance of bridge deck by adding fiber material into concrete.However,due to the influence of different types of fiber and various fibers with different volume ratios on the cracking performance and bearing capacity of concrete bridge deck is relatively limited,the rationality and scientific nature of this disposal measure is still lack of strong theoretical and experimental data support.This paper mainly adopts the finite element simulation analysis method and AQBAQUS analysis software to establish a homogenization analysis model for the fiber-reinforced concrete bridge deck,and studies the change law of initial crack and crack growth of different fiber-reinforced concrete bridge deck under static and dynamic effects.The main research work is as follows.1)The homogenized elastoplastic constitutive models of steel fiber concrete,polypropylene concrete and basalt fiber concrete are established after systematic analysis of the experimental and theoretical results of fiber concrete at home and abroad.Nonlinear spring elements are adopted to simulate the ideal elastic-plastic the bond-slip effect between reinforcement and fiber reinforced concrete,fiber concrete bridge deck is established of the three-dimensional entity unit refinement finite element model of elastic and plastic damage analysis and field test results of basalt fiber reinforced concrete bridge panel,verify the reliability of the simulation analysis.2)Based on the actual engineering bridge deck design case,the static failure state of all kinds of fiber concrete under local wheel pressure loading with different fiber volume ratio was analyzed.The analysis results show that increasing the volume ratio of fiber can increase the initial crack damage load of fiber concrete bridge deck and effectively restrain the development of cracks.2%volume ratio of steel fiber,0.2%volume ratio of polypropylene fiber and 0.2%volume ratio of basalt fiber are the optimal volume ratio of all kinds of fiber bridge panels,respectively.The basalt fiber concrete with 0.2%volume ratio can achieve better crack resistance and toughening effect,and has better ductility and bearing capacity.3)According to the analysis condition of cyclic loading under wheel pressure,the variation rule of damage range,bearing capacity difference and deflection deformation difference of various fiber concrete bridge panels are systematically studied.The results show that adding fiber reinforced material to C50 concrete can effectively reduce the damage degree,plastic damage range and crack width of slab bottom concrete under cyclic wheel pressure.Among them,the steel fiber with 2%volume content has the best anti-crack performance in reducing the damage extreme value of the bridge panel and controlling the distribution of damage area.