| As the significant force site of reinforced concrete frame, joint region is a weak link ofstructure seismic. The study about frame joints is always carried out in two ways: one isconfined to joints focusing on the mechanism of fracture and shear behavior of joint region,and the other is according to the whole structure to study the joints and proposing reasonabledesign method to make sure the security of core region. The seismic code requires strongcolumn and weak beam, strong joint weak component.So the normal requirement is that theplastic hinge of beam-end is before the column-end and the column-end is before the joints, inthis situation this paper is mainly studying the behavior of joint region after the yield ofbeam-end.The anti-seismic behavior incluing bearing capacity, shear capacity and deformabilityof nodes and energy-dissipating capacity is studied in this paper by reversed cyclicquasi-static loading test of reinforced concrete frame beam-column end nodes of two planes.Then finite element analysis of the reinforced concrete frame exterior joints is made usingABAQUS to study the influence of different axial compression ratio and reinforcement ratioof longitudinal steel on anti-seismic behaviors of structure. At the end,the paper verifyscurrent design methods combining test result and finite element analysis. The conclusion is asfollows:(1) The reinforced concrete beam-column-end joint specimens designing according tothe current code do not occur break on joint core region, which means the design based oncurrent code is safe and reliable.(2) Along with increase of the beam-end flexural strength ratio,the break turns fromcolumn concrete crush failure to beam plastic hinge. The current code stipulates the columnflexural strength ratio to realize strong column and weak beam.(3) If the beam yield failure happens in end nodes, the changes of column axialcompression ratio has little effect on joint carrying capacity and seismic behaviors. (4) Along with the increase of reinforcement ratio of longitudinal steel, the beam endappear plastic hinge which observable improve joint ultimate carrying capacity and seismicbehaviors. On condition of strong column and weak beam, the increase of reinforcement ratioof column longitudinal steel improves joint ultimate carrying capacity and seismic behaviors(5) To the reinforced concrete beam-column exterior joints, on the condition of ignoringthe improvement of carrying capacity of plates and walls to beams, the current code canmake sure to realize the anticipative failure modes of strong column and weak beam. So therelevant requirement in current code is reasonable. |
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