Research Of Flexural Performancer Of Reinforced Concrete Beam Strengthened With Angle Steel By Dry Connection

At present,there are a large number of old buildings in many cities in China,which are mainly reinforced concrete structures.As people pay more and more attention to the safety and durability,seismic performance and scientific and technological progress of buildings,the structure of these buildings may not meet the bearing capacity requirements of the current design codes in China.If they are demolished and rebuilt,they will not only waste a lot of resources,but also do not meet the requirements of modern green environmental protection.Therefore,the reinforcement and transformation of the structure of old buildings is a research hotspot at present.The dry connection of angle steel to strengthen concrete beam belongs to the method of outsourcing section steel reinforcement,which has the advantages of convenient construction,short construction period and no on-site wet operation,and can effectively improve the bearing capacity of the original reinforced concrete beam.However,at present,there are many studies on strengthening reinforced concrete structure with I-beam and steel plate at home and abroad,and most of them need to use structural adhesive for wet operation,which requires corresponding maintenance age,The research on strengthening reinforced concrete beams with angle steel dry connection is relatively few,and more research is still needed.In this paper,the bending behavior of reinforced concrete beams strengthened with angle steel is studied by the combination of test and finite element simulation.The following research results are obtained:(1)Through the three-point static load test of one reinforced concrete beam and five reinforced concrete beams strengthened with angle steel,the different reinforcement effects of two angle steel and four angle steel on reinforced concrete beams are studied,as well as the influence law of simply using bolts to anchor angle steel on the beam side and U-shaped hoop plate and bolts to anchor angle steel on the reinforcement effect of reinforced concrete beams,and its failure mode is analyzed.The test results show that the specimens with bolt anchored angle steel show flexural failure during loading,there are certain signs before failure,and can greatly improve the flexural capacity of the original reinforced concrete beam,which has a good reinforcement effect;The flexural bearing capacity of reinforced concrete beams strengthened with four angle steel is greater than that of reinforced concrete beams strengthened with two angle steel;When the bolt spacing is equal,the u-hoop plate can further improve the flexural capacity of the strengthened beam.(2)The effect of bolt spacing on the bending resistance of aqus is studied by finite element simulation.The results show that different bolt spacing parameters have effects on yield load,ultimate load,ductility and failure mode.With the increase of bolt spacing,the flexural capacity of strengthened beams decreases;When it exceeds a certain range,the angle steel of the reinforced beam will slip and the beam will be damaged in advance.(3)Based on the test and finite element simulation results,this paper discusses the calculation method of normal section flexural capacity of reinforced concrete beams strengthened with angle steel dry connection;Reasonable structural arrangement of angle steel bolt spacing.