Study on influencing factors of hysteretic performance of cantilever fully-bolted prefabricated beam-column joint

Abstract

In order to improve the construction efficiency and integrity of prefabricated RC frames, a cantilever fully-bolted prefabricated beam-column joint is proposed. Through the reciprocating loading test, the change rules of rotation characteristics, mechanical properties and stiffness degradation of this type of joint were obtained. The failure mode of the joint is found: the steel plate in the connection area undergoes a slight flexural deformation, the concrete on the outside of the connection area forms a plastic region of about 1/3 beam length, the concrete crack develops obliquely from horizontal cracking with the increase of stiffness, and the damage characteristic develops from bending damage to shear damage. The initial stiffness of the precast joint is about 1.5 times that of the cast-in-place joint, the yield load is increased by 31 %, the peak load by 52 % and the ductility coefficient by a maximum of 96 %, with significantly better mechanical properties than the cast-in-place joint. Parametric analysis was carried out based on the tests. When the flexural stiffness ratio of the cantilevered section to the reinforced concrete beam section is less than 0.5, it is a weak connection. Damage to the section cantilever section occurs, and the stiffness degrades significantly. It is recommended that the joint be designed for a strong connection, with a stiffness ratio of around 0.6. The cantilever section's length greatly influences the joint's stress transfer. It is recommended that the length be taken to be about 0.6 and no greater than 0.75 for the width of the precast reinforced concrete beam. The design process of a prefabricated RC frame is given on this basis. A research basis has been laid for the engineering application of this new type of connection.