Study On Mechanical Behavior And Computational Method Of Shear Connections Of FRP Profile-concrete Composite Beams

In recent years,FRP profiles-concrete composite beams have developed rapidly as a new type of structure,which makes full use of the characteristics of light weight and high strength of FRP materials,but its normal work depends on reliable interface connection.Because of the non-weldability of FRP materials,it is particularly urgent to develop new interface connection methods.In this paper,the Bolted-Pouched FRP Shear Connector(BPFC)is proposed.Its mechanical properties are evaluated by 11 push-out specimens,and the corresponding calculation method is deduced based on finite element analysis and failure mode of the connector.In this paper,the following research work is carried out in connection with the National Key Research and Development Program of the 13 th Five-Year Plan(2017YFC0703005),"Research on Pultrusion Profile Components and New Structural Systems of Industrial Standardized Fiber Reinforced Composites" :Four high strength bolt connectors,four perforated plate connectors(PFC)and three BPFC were tested.There are three failure modes for three types of connectors: bolt shear,reinforced concrete shear and FRP plate shear failure.The influence of spacing and row number on the bearing capacity of single connector is studied.The results show that the spacing and row number have little effect on the bolted connector,but have great influence on the PFC connector.The bearing capacity of single connector increases with the increase of spacing and decreases with the increase of row number.The bearing capacity of PFC connector is mainly provided by concrete tenon and perforated steel bar,and its ductility is guaranteed by perforated steel bar.Based on the experimental phenomena and finite element results,the whole process of failure of bolted connectors and PFC under stress is analyzed.The stress state of each component of the specimens is defined,and the plastic damage area and the change rule of the concrete slab are described.According to the different failure modes and the results of finite element analysis,the corresponding bearing capacity calculation method is put forward.The calculated values are in good agreement with the experimental results,and the calculation formula has good accuracy.Based on the load-slip curve of the test,the anti-slip stiffness values and calculation methods of three types of connectors are given.The results show that the stiffness of PFC connector is the largest,BPFC is the second,and bolt connector is the smallest.The bearing capacity of single connector is calculated.BPFC is the largest,PFC is the second,and bolted connector is the smallest.The results show that BPFC and PFC have excellent bearing capacity and slip resistance,and the failure of PFC is ductile.These two types of connectors are good choices for FRP profile-concrete composite beam interface connection.