Analysis Of Flexural Performance Of Existing RC Beams Strengthened By High-strength Grouting Material

With the rapid development of transportation industry in our country,in addition to building Bridges,some Bridges with longer service life need to be strengthened.As a common bridge reinforcement method,increasing section reinforcement method has been well applied in the field of bridge reinforcement because of its characteristics of simple construction,wide application range and mature technology.However,if ordinary concrete is used as the new material to strengthen the member,it is not only easy to crack,but also will lead to the reduction of the bonding strength between the old and new concrete.With the continuous in-depth research on high-strength grouting materials in recent years,the excellent performance of highstrength grouting materials has been widely recognized by the engineering field,and it is gradually applied in the reinforcement industry.According to the existing research data,it is an economical,durable and efficient method to strengthen RC beams with high strength grouting material as new material.In this paper,nine beams reinforced with high strength grouting material and two beams for comparison pouring are designed on the basis of engineering practice,and the bending performance of each beam under different conditions is experimentally studied and theoretically analyzed by using the single-side reinforcement method of increasing section.In this paper,the influences of different design parameters on the crack development,stress distribution,bending resistance and failure mode of the reinforced beams are studied by considering the initial stress level,the thickness of the reinforced layer,the spacing of the reinforcement bars and the ratio of the reinforcement longitudinal bars.The test results show that the mechanical properties and safety properties of the reinforced beams can be effectively improved by using high-strength grouting material as the new reinforcement material.The increase of the reinforcement thickness at the bottom of the beam can only improve the stress difference between the old and new longitudinal bars in a limited range,and the increase of the bending capacity of the beam is not obvious.Appropriate spacing between the planting bars has a good effect on the bonding performance of the new and old concrete,but different spacing between the planting bars has little effect on the flexural performance of the reinforced beams.With the increase of reinforcement ratio of longitudinal reinforcement at the bottom of the beam,the flexural capacity of the reinforced beam will increase to a certain extent.With the increase of the initial stress level,the flexural bearing capacity of the reinforced beams decreases,and the stiffness of the beams degenerates to a certain extent.Based on the test results,a method for calculating the flexural capacity of RC beams strengthened with high strength grouting material is proposed,and the calculated results are in good agreement with the test results.At the same time,the finite element simulation software ABAQUS was used to simulate the loading process of the test,and a numerical model which could correctly simulate the beam strengthened with high strength grouting material was proposed.The comparison with the test results showed that the accuracy was good.The above research results have clarified the influence of different design parameters on the flexural performance of RC beams strengthened with high-strength grouting materials,which can provide a basis for the reinforcement and reconstruction of real Bridges.