Study On The Performance Of Simple Bar Connectors Using Gouted Sleeves

Compared to the traditional cast-in-place bridge,the prefabricated bridge has the advantages of high degree of industrialization,saving material,small pollution,convenient construction,small amount of worksite wet work and workers,easy to control t he quality of prefabricated components,short construction period,fast recovery of investment and so on.It is the direction of the industrial development of new types of bridges.The reliable connection of bars in the prefabricated piers is the key to ensur e the good seismic performance of the assembled pier,and it is also the key to the application of the prefabricated bridge.In this thesis,two kinds of rebar joints are de signed: one is metal corrugated pipe grouting rebar lap joint,the other is seamless st eel pipe grouting rebar butt joint.The mechanical behavior of reinforcement joints is studied through experiments,theoretical analysis and finite element simulation.The re search in this thesis is as follows:(1)A uniaxial tensile test was performed on 10 specimens of 2 kinds of joints.The failure mode,ultimate bearing capacity,residual deformation,maximum total forc e elongation,load-displacement curve and strain distribution of the rebar were studied.And the effect of the lap length of the rebar,the length of the seamless steel pipe,t the length of the welded short rebar on the ultimate bearing capacity of the joint we re analyzed.There were three failure modes in the test speciman: metal bellows brea king,rebar breaking and rebar bonding slip.(2)Through the analysis of the test results,the ultimate bearing capacity of the metal bellows joint increases with the increase of the lap length of the rebar;the ulti mate bearing capacity of the seamless steel pipe joint increases with the length ofthe steel pipe,and the average bond strength decreases with the increase of the length of the steel pipe.Welding short rebars can increase the bearing capacity and bond stre ngth of the joints,but the increase sffect is limited.(3)Based on the thick-walled cylinder model in elastic mechanics,reference is made to the theoretical research on the stress mechanism of the cylindrical grouting s leeve,the calculation formula of the initial restraint stress between the steel bar and the grouting material,and between the steel pipe and the grouting material,the form ula for calculating ultimate bearing capacity of joints with bond slip failure.The ultimate bearing capacity of 4 specimens with bond slip failure is calculated,which is i n good agreement with the test data.(4)The finite element software ANSYS was used to numerically simulate the joi nts of seamless steel tubes.The load-displacement curves of the joints obtained by fi nite element simulation were basically consistent with the curves obtained from the te sts,and the strain distributions of the steel bars were basically the same.The axial s tress in the middle of the steel tube is the tensile stress and the value is the largest.The tensile stress from the middle to the end of the steel tube gradually decreases,a nd the stress at the end of the tube changes from tensile stress to compressive stress.