Experimental Study On Anchorage Properties Of Coated Ribbed Steel Bar And Concrete As Well As Finite Element Modeling

Steel bar in concrete structures is prone to corrosion in marine environment.Reinforcement corrosion not only affects the structural safety,but also reduces durability and shortens service life of structures.The epoxy coated steel bar is one of the effective way to protect the steel bar from corrosion,but coating will change the surface conditions of steel bar such as rib height,rib spacing and inclination angle of rib,these will affect the bond behavior between steel bar and concrete.Therefore,in this paper,the anchorage properties between coated steel bar and concrete were studied for the newly developed toughened epoxy cement-based coating.The main research contents are as follows:(1)Experimental study on anchorage properties of toughened epoxy cement-based coated steel bar with concrete: The main factors affecting anchorage properties,such as diameter of steel bar,strength of concrete,thickness of protective layer,stirrup ratio and anchorage length,were systematically analyzed by pull-out specimens.(2)Analysis of anchorage length of coated steel bars in concrete: Based on the calculation formula of ultimate bond stress between coated steel bar and concrete,the anchorage reliability of coated steel bars is analyzed by statistical mathematics method,and the calculating formula of anchorage length of coated steel bars suitable for different concrete strength grades is put forward.(3)Experimental study on bond strength mechanism between coated steel bar and concrete.Adsorption and friction coefficients of interface between different kinds of coated steel bars and corroded or not steel plate and concrete were measured by adsorption force test and friction test respectively.The influence of rib height,rib spacing and inclination angle of ribbed steel bars on the biting action between steel bars and concrete by bite force test.(4)The numerical simulation study on the influence of steel bar shape parameters on anchorage properties: Based on the load-slip constitutive curve of different coated steel bar and concrete,the interface parameters suitable for coated steel bar and concrete are determined.The anchorage properties between steel bar and concrete was analyzed by changing the rib height and rib spacing of steel bar,Finally,the objective of optimizing anchorage properties is achieved by adjusting the parameters of steel bar and coating material.