Seismic Behavior Of Rc Beam To Partially Steel Tubed Concrete(PSTY)column Joints Under High Axial Load And Cyclic Loading

Steel tubed concrete(STC) column is one of the methods for seismic retrofit. Steel tube acts as the transverse reinforcement, providing the confinement to the concrete as well as prevent the longitudinal reinforcement from buckling. This idea was first came out for bridge column retrofit which achieved a great success. Recently, some scholars begin to promote it to the new reinforced concrete(RC) buildings. Therefore, a new type of partially steel tubed concrete(PSTC) column is proposed in that is suitable to be used in new high rise RC buildings and its seismic behaviors of the beam-to-column joint are discussed. Compared with the conducted research, there are four innovations in this thesis: 1) The object of study is the medium length-frame column in new buildings. 2)Steel tube is arrange along plastic hinge region, mainly for providing the lateral confinement other than shear resisting. 3) The column is high axial loading. 4)Slab and intersecting stub beam are also considered.The main task and result of the research are concluded as follow:①Three exterior joint specimens consisting of RC beams and PSTC columns and two exterior RC joint specimens were designed and tested under high axial load and cyclic loading to investigate the joint behavior in terms of failure pattern, hysteresis response, deformation, energy dissipation capacity and degradation of strength and stiffness. Test results indicate that the PSTC column can benefit the performance of the joint in terms of strength, ductility and energy dissipation capacity and can partly compensate for the unfavorable effect induced by slab. The strong column-weak beam mechanism can also be ensured in RC beam to PSTC column joint.② Five specimens were modeled and analyzed numerically. The results from simulations were proved that the hysteretic behaviors of PSTCC and RC joints subjected to cyclic loading can be well predicted.③ Based on the confirmed numerical modal, three factors, say ratio of section dimension to the thickness(B/t) of steel tube, length of steel tube and axial load ratio, were investigated for slender column and short column, respectively. The results showed that a better performance can be achieve when B/t was in the range of 30-83.3. The length can be well designed by following the rules for transverse reinforcement in plastic hinge region. With the increment of axial load, a better ductile behavior of the joint can be pursued.