Research On Flexural Performance Of Hybrid Reinforced Concrete Beams With Quenching And Self-tempering Ribbed Bars And FRP Bars

Quenching and self-tempering ribbed bars is a kind of low cost and high performance steel bar which is obtained by the heat treatment process after rolling.It has the advantages of high strength,low production cost and simple production process.Due to the influence of the production technology,the material properties is instable,and the application of the quenching and self-tempering ribbed bars in the field of civil engineering is limited.With the innovation of production technology,quenching and self-tempering ribbed bars mechanics performance is stable,and it is widely used in Europe and the United States and other countries.FRP bar has the advantages of high strength,good durability,and light weight.In hybrid reinforced beam,FRP bars can make up for the shortage of quenching and self-tempering ribbed bar.The paper will study the problemIn order to research the flexural properties of RC beams strengthened with the quenching and self-tempering ribbed bars,3 beams are designed in this paper.The results show that the failure characteristics of concrete beams which use of the quenching and self-tempering ribbed bars are the same as those of ordinary reinforced concrete beams.By comparing the experimental value and theoretical calculation of bearing capacity,deflection and crack width,this paper draws the following conclusions: The bearing capacity and the maximum crack width of RC beams strengthened with the quenching and self-tempering ribbed bars can be calculated by the formula in the code and has a high safety reserve;The deflection formula of RC beams strengthened with the quenching and self-tempering ribbed bars should be multiplied by the magnification factor of 1.25 on the formula in the code.In this paper,7 hybrid reinforced beams are designed,and the flexural behavior of the normal section is studied.According to the test results,it can be concluded that the failure modes of the composite beams have three types: failure of less-reinforced member;balanced failure;failure of over-reinforced member.The failure process of the hybrid reinforced beam is that,with the increase of the load,the rebar yield,and the tensile stress of the FRP bar is smaller due to the smaller elastic modulus.After rebar yield,the stress of FRP bars is beginning to grow rapidly.In the process of increasing the stress of FRP bars,the upper concrete is crushed.In order to ensure the failure mode of the beam is balanced failure,according to the critical state of the strain,the reinforcement ratio of the reinforced beam is limited.On this basis,this paper analyzes the effect of the ratio of FRP area and quenching and self-tempering ribbed bars area of hybrid reinforced beams,and that limit its scope.In addition,this paper also calculates the economic reinforcement ratio of the hybrid reinforced concrete beam and puts forward some suggestions.Finally,the ANSYS software is used to model the hybrid beam,and the finite element analysis results are in good agreement with the actual values.