Research On Flexural Capacity Of Reinforced Concrete Beam Strengthened With Bolted Bottom Steel Plate

With China's construction industry transitioning from a large-scale construction phase to a construction and retrofit maintenance phase,Building reinforcement and renovation have become a hot topic.Due to the lack of consideration in the design of reinforced concrete structures,or the fact that reinforced concrete components are corroded in special circumstances,which leading to the flexure members in the building will not meet the requirements for use because of the insufficient bearing capacity of the normal section.In this case,the structure or component must be reinforced.The technique of strengthening by bolting steel plates can effectively improve the bearing capacity,stiffness and ductility of the reinforced components.Compared with the traditional paste reinforcement method,the technique of strengthening by bolting steel plates is low in cost and simple in construction,and can effectively avoid peeling between the steel plate and the concrete,and is more resistant to high temperatures.At present,the study on strengthening by bolting steel plates is not enough,there are many factors that affect the reinforcement effect and there is no complete theory and design specification.Based on this,this paper uses a combination of numerical simulation and experimental analysis methods to further study the flexural performance of reinforced concrete beam reinforced with beam anchor bolt steel plate.Through the finite element numerical simulation of the shear of a single anchor bolt,this paper researched on the shear performance of single anchor bolts and the effect of substrate strength grade,anchor bolt diameter,and embedment depth of anchor bolts on shear performance,and obtained the characteristics of shear resistance of the root anchor bolt and the change law of shear resistance in the influence of the three factors;through experimental study on reinforced concrete beam strengthened with bolted bottom steel plate,this paper analyzed influence of anchor bolt diameter,number of anchor bolts,secondary force,anchor bolt arrangement on reinforcement effect,and obtained the influence law of the influencing factors on the reinforcement effect,and make a suggestion about engineering practice.In the study of the diameter of anchor bolts,this paper proposed the definition of opening hole rate,and the open hole rate was limited to ensure that the reinforced beam would not be reduced in stiffness due to the excessive diameter,so that the technique of strengthening by bolting steel plates can better applied in engineering practice;through experimental study on reinforced concrete beam strengthened with bolted bottom steel plate,this paper analyzed the force conditions of the various components of the reinforcement beam,obtained the force characteristics of the reinforcement beam,and deduced the calculation formula of the flexural capacity of the reinforced beam for positive reinforcement by combining the results of the experiments and numerical simulations.Finally,the formula and the comparison with the test values prove the rationality of the formula;through finite element analysis of reinforced concrete beam strengthened with bolted bottom steel plate,this paper discussed the effects of anchor diameter,number of anchor bolts,secondary force,and anchor bolt arrangement on the reinforcement effect,and compared with the experimental results to verify the conclusions of the study.