Experimental Study On Precaset Concrete Beam-To-Column Joints Connected By U-Shaped Reinforcing BARS

In 1999, the technology for framed structures comprised of precast prestressed concrete components named Scope system was introduced from France by our country. Besides the advantages of precast structures like the high construction speed, assurance of quality and environmental benefits, it also has following outstanding characters as the convenient adoption of prestressed prestensioning method, reduction of construction cost and low amount of steel usage etc.Based on the research of the former scholars and the National industry standard, three exterior beam-column joint members under low-cyclic reversed loads were studied in this paper to do further research on the beam-to-column joints. After experiments, the finite element analysis on casting members was also conducted to compare with the experiment members. Based on these results, mechanical properties of structure were investigated. The main contents are as follows:(1) Three joint members were chosen to be studied by experiments, considering the affects by different reinforcement ratio and the existence of service hole After experiments, with phenomenon analyzed and the data dealt with, the estimation was given on the seismic performance of Scope system joint on the basis of the mechanism on the beam-column connections, as well as ductility, hysteresis curves, energy dissipation etc.(2) With the help of OpenSees, the corresponding numerical model was created and analyzed. Comparing with the experimental results, the simulation provided us a relatively accurate prediction about the reloading stiffness, unloading stiffness and strength degradation, reflecting the shape and pinching effect of the hysteresis curve obtained in the actual test. Using different nonlinear macro beam-column element and shear model theory about the joint core, the rationality of the model created was discussed.(3) To explore the influence of various parameters of the joint on seismic performance, numerical simulation was made using OpenSees.(4) Finally, the paper pointed out the deficiencies and provided some suggestions for the study based on the test resultsAccording to the test and analysis, some conclusions can be reached as follows:The joints of Scope system designed according to the existing design of concrete structure code perform well under earthquake action. Week-joint and Strong-member should be avoided by the assurance of the shear capacity of the joint core. The nonlinear finite element software OpenSees simulates the beam-column joints under low reversed cyclic loading relatively accurately...