Shear Behavior Of RC Beams Strengthened Using UHPC Panels

Reinforced Concrete(RC)structures are widely used in construction.As one of the main load-bearing components,RC beams may experience shear performance degradation due to environmental corrosion,seismic activity,and other factors,which can compromise structural safety.Therefore,it is necessary to strengthen and maintain them to extend their service life.Currently,common methods for strengthening RC beams include enlarging the section,external steel jacketing,and bonding fiber-reinforced polymer composites(FRPs).However,these methods have drawbacks such as poor durability,long construction periods,or susceptibility to environmental effects,making them unsuitable for complex corrosive environments such as those near the sea.Therefore,an economical,efficient,and durable shear strengthening method needs to be explored.Ultra-high-performance concrete(UHPC)and fiber-reinforced composites(FRP)are two materials commonly used for reinforcing RC beams.UHPC has high strength,high toughness and high durability.FRP is lightweight,high strength,and has excellent tensile performance.In view of the advantages of the two materials,this paper proposes a method to strengthen RC beams with UHPC prefabricated panels reinforced with CFRP strips.In this paper,the shear behavior of UHPC prefabricated panels reinforced RC beams was studied by combining experimental verification and numerical simulation,and on this basis,the influence of the main parameters on the shear behavior under different shear-span ratios was systematically analyzed.The main research content and results of this paper are as follows:(1)An experimental research was carried out on the shear performance of RC beams reinforced with UHPC prefabricated panels.Six large-scale test beams were designed and fabricated,and four-point loading tests were conducted to study the effects of UHPC panel thickness,CFRP strip reinforcement ratio,and UHPC panel configuration on the shear performance of RC beams.The test results show that the ultimate load and stiffness of the RC beams strengthened are greatly improved.The thicker the the UHPC panels,the higher the shear capacity of RC beams;The CFRP strips can further improve the stiffness and shear capacity of RC beams.The use of UHPC panels was found to be more effective than using UHPC panel strips.(2)Using the finite element analysis software DIANA,a finite element model(FEM)of RC beams reinforced with UHPC prefabricated panels was established.Comparison with the experimental data showed that the finite element simulation results matched well with the experimental values,which verified the accuracy of the established FEM.Based on this,parameter supplement simulation analysis of the shear performance of RC beams was carried out using the verified FEM.(3)The influence of the mains parameters on the shear performance of RC beams under different shear-span ratios were studied by finite element simulation.The results showed that the laws of influence were different on the shear behavior of RC beams under different shear span ratios in terms of UHPC panel thickness,the reinforcement ratio of CFRP strips,matrix concrete strength,and the configuration of UHPC panels.Therefore,appropriate parameters need to be selected according to a certain shear span ratio.