| With the rapid development of economy and the diversification of the building form, the regular reinforcements cannot meet the requirements by civil engineering due to the limitation of energy, resources and environment. Hence, it is inevitable to adopt high-strength reinforced bars in engineering. Since China is one of the countries that have experienced strong earthquake activity and serious earthquake, earthquake resistant design has become the most important part in structural design. For a large number of reinforced concrete frame structure buildings, the beam-column joints serve as the key part which can seriously affect the seismic behavior of the structure. However, experimental and numerical analysis of RC beam-column joints reinforced with HRB500 E, a new kind of high strength reinforcement developed for aseismic structures, is rather limited. In this paper, experimental investigation and numerical analysis are carried out to study the mechanical behaviors of RC beam-column joints reinforced with HRB500 E under cyclic and monotonic loading. And the data presented in this paper provide testing and academic basis for applying HRB500 E into practical engineering.Firstly, four full-scale specimens of RC beam-column joints designed according to the relevant norms and standards in our country were tested under cyclic low-frequent loading. Among them, two specimens were reinforced with HRB500 E, while the others were reinforced with HRB335. The crack development, collapse mode, hysteretic characteristics, energy dissipation, ductility and stiffness degradation obtained from the quasi-static tests were analyzed. The results indicated that RC beam-column joints reinforced with HRB500 E have a similar collapse mode with those reinforced with HRB335. In addition, all of the specimens, regardless of their different kinds of reinforcements, had a good ductile behavior. Furthermore, specimens reinforced with HRB500 E have a higher bearing capacity, deformation capacity and energy dissipation, which indicated that they had a better seismic performance.Then, six extra full-scale specimens of RC beam-column joints were designed according to related specifications. Among them, two specimens were reinforced with HRB500 E, two with HRB600, while the others were reinforced with HRB335. And one of the two specimens reinforced with the identical kind steel bars was tested under cyclic loading and another one was tested under monotonic loading. The main objective of this experimental campaign was to study and compare the different behaviors of RC beam-column joints under different load patterns and to make a further study on the superiority of applying HRB500 E.Finally, the numerical study was performed using the software ABAQUS and three-dimensional(3D) finite element models of RC beam-column joints under monotonic loading were established. A comparison of the numerical and experimental results was presented to validate the simulation and the results indicated a good agreement. A parametric study was subsequently performed to elucidate the role of the stirrups in the joint core region and how the stirrup ratio and column axial load influenced the joint behavior. |
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