Experimental Study On Seismic Performance Of Seismic Damaged Fabricated Groove Frame Beam With High Ductile Concrete

High ductility concrete(HDC)is a new building material with high strength,high ductility and multiple cracks.At present,it has been widely used in the reinforcement of reinforced concrete structure.To study the performance and effect of reinforced fabricated structure reinforce by high,ductility concrete,this paper uses high ductility concrete to repair and reinforce one seismic damaged frame beam and three seismic damaged fabricated groove frame beams,and studies its seismic performance after reinforcement through low cycle cyclic loading test,It also provides a certain reference basis for the reinforcement and repair of actual seismic damaged structures and fabricated structures.In this test,seismic damaged frame beam and seismic damaged fabricated groove frame beams are reinforced by increasing the section method,the damaged layer on the surface of the seismic damaged structure is chiseled by ultrasonic detection technology,and then the high ductility concrete is reinforced on the surface of the chiseled structure.After the maintenance is completed,the ultrasonic technology is used to detect and analyze the bonding performance of the old and new concrete.The test mainly studies and analyzes the influence of the lateral and bottom connection steel plates of the reinforced seismic damaged fabricated structure on the reinforcement performance,comparison performance of seismic damaged frame beam and seismic damaged fabricated groove frame beam reinforced by high ductility concrete,and the difference of the seismic performance of each specimen before and after reinforcement.The test results show that:(1)Through the low cycle repeated loading of the seismic damaged frame beam and the fabricated groove frame beam after the reinforcement of high ductility concrete,it can be seen from the test phenomenon that the damage of the seismic damaged fabricated groove frame beam after the reinforcement is mainly concentrated in the post cast composite layer,the connection Part of concealed corbel and the middle of lateral connection steel plate,while the seismic damaged frame beam after the reinforcement is mainly damaged in the joint surface of new and old concrete.It can be seen that the high ductility concrete surface can effectively inhibit the formation of structural surface cracks and improve the characteristics of brittle failure of the original specimen and further transform it into ductile failure.(2)The thickness of lateral connection steel plate and bottom connection steel plate of fabricated groove frame beam reinforced by high ductility concrete can improve the bearing capacity,stiffness degradation,bearing capacity degradation and characteristic value of bearing capacity at each stage.Due to the rigid constraints of lateral connection steel plate and bottom connection steel plate on the fabricated structure,in terms of ductility and energy dissipation capacity,There is no significant improvement effect on the reinforced seismic damaged fabricated groove frame beam.(3)The hysteretic curve of frame beam strengthened with high ductility concrete can completely envelope the original curve,and the related seismic performance has been improved.After reinforcing the seismic damaged fabricated groove frame beam with high ductility concrete,the seismic performance of the original structure can be basically restored,but it can’t significantly improve the seismic performance of the original fabricated groove frame beam.According to the basic principle of ultrasonic propagation,ultrasonic flaw detection is carried out for each specimen before and after reinforcement,the thickness of damage layer after the initial earthquake damage is calculated,and the bonding performance between high ductility concrete and the original specimen is analyzed.During the loading process of each reinforced specimen,the ultrasonic sound velocity under each stage of loading displacement is collected.According to the attenuation law of sound velocity and obtain the damage change law in the reinforced member of high ductility concrete.Combined with the relationship between ultrasonic and stress to propose a material damage constitutive model based on ultrasonic parameters.Finally,combined with the relevant specifications and the calculation model of tension and compression bars to establish the internal force balance relationship of the fabricated tongue and groove connection frame beam and to calculate the shear bearing capacity of the frame beam and fabricated groove frame beam before and after reinforcement.Through the comparative analysis of the test value and calculated value of the shear bearing capacity of each specimen,the tension compression bar model is suitable for the calculation of the shear bearing capacity of each specimen.