Study On Shear Capacity Of FRP Bar Reinforced Concrete Members Considering Effective Height

Reinforced concrete structure is the structure style that most widely used in the field of water conservancy engineering,civil engineering,transportation engineering,ocean engineering.However,the corrosion of steel bars will lead to the deterioration of the performance of concrete structure,and then affects normal use and even causes safety accidents.Fiber reinforced polymer(FRP)bars are formed through pultrusion of one,or more types of fibers and polymers.FRP bars have the advantages of high corrosion resistance,high strength-to-weight ratio,good fatigue characteristics and magnetic neutrality.In this paper,the shear capacity of FRP bar reinforced concrete members without web reinforcement,in which all the steel bars are replaced by FRP bars,is studied by experiments and intelligent algorithms.The main contents of this study are as follows:(1)The crack development and failure modes,deformation performance,strain of FRP bars,shear capacity and maximum crack width of five HFRP bar reinforced concrete members without web reinforcement in the shear tests under concentrated load,are analyzed.The results show that the load-deflection curve of all specimens is the double broken line.The cracking point of the specimen is the dividing point of the slope change of the load-deflection curve,and there are no obvious yield stage and descending stage after cracking;In the same case,the mid-span deflection decreases with the increasing of the effective height of the specimen.(2)The shear mechanism and influencing factors of shear capacity of FRP reinforced concrete members without web reinforcement are analyzed.The calculation formulas of shear capacity of FRP reinforced concrete members without web reinforcement in various codes are introduced,and the reliability of various codes on predicting the shear capacity of HFRP bar reinforced concrete members without web reinforcement is compared,including GB50608-2020,ACI 440.1R-15,CAN/CSA S6-14,CAN/CSA S806-12,CNR DT203-2006,JSCE-97 and BISE-99.Based on the data in this paper and published literature,the calculation formula of the Chinese code(GB 50608-2020)is modified,and the calculation formula of shear capacity of FRP reinforced concrete members without web reinforcement considering size effect is proposed.(3)A modified BP model named particle swarm optimization(PSO)BP model is used to predict the shear capacity of FRP bar reinforced concrete members without web reinforcement in this study.The PSO-BP model is trained and tested based on 398 sets of experimental data in this paper and published literature.By comparing the prediction results of this model with those of the BP model and existing models,it shows that PSO-BP model can accurately predict the shear capacity of FRP reinforced concrete members without web reinforcement.