Experimental Study On The Shear Capacity Of Concrete Beams With GFRP Stirrups

Nowadays,the durability problems caused by the corrosion of steel bars in reinforced concrete structures have attracted people’s special attention.Scholars have proposed to use high-durability reinforced FRP material(with high tensile strength,good corrosion resistance,light weight and other advantages)instead of ordinary steel for practical engineering to improve the corrosion resistance of beam components.However,at present,there are many studies on the flexural behavior of FRP bar-beams(FRP is used as longitudinal reinforcement bars)and has little research on FRP tendons used as stirrups to resist shear.On the basis of this,the experimental research of the behavior of the reinforced concrete beams with the GFRP stirrups is carried out.The main contents are as follows:1.The production process,physical and mechanical properties of FRP material and the research and application status of FRP reinforced concrete structures are introduced,analyze and study the shear calculation model of the typical reinforced concrete beams and the calculation formula of the shear capacity of beams in each country.2.According to the experimental study of 5 GFRP stirrup concrete beams and 1control beams under shear,the deformation behavior of the beam under the concentrated load,the characteristics of diagonal cracks,failure mechanism,the strain of the GFRP stirrups,concrete strain of shear-compression zone of beams and longitudinal reinforcement strain are analyzed.This paper focus on the analysis of shear-span ratio and the stirrup ratio which can affect the shear-cracking load,shear capacity and m-aximum diagonal crack widths of beams.3.Based on the considering concrete softened truss theory,combined with the balance condition,constitutive relation and deformation coordination conditions,the formula of shear capacity of concrete with reinforced concrete beams is proposed.Secondly,the shear formula of FRP stirrups considering the stress unevenness of stirrups is deduced,Finally,the shear force calculation formula of FRP beams is obtained by adding the two parts of shear force.Through comparative analysis,the theoretical value of the formula is in good agreement with the measured value.4.According to the analysis of the coincidence degree between the calculatedvalue of the crack load formula and the measured cracking load value of the beam member,the formula for calculating the shear crack of the GFRP stirrup test beam is put forward.5.The finite element software of the ABAQUS is used to establish the nonlinear models of the GFRP stirrup concrete beams by choosing proper material constitutive model,element type,etc.After verification,the effects of concrete strength and reinforcement ratio on shear-deflection curve of beam are studied.