A Super Element Beam-Column Joint Model Under Dynamic Loading

Abstract

Several analytical beam-column joint models with varying complexities have been proposed to give reliable estimate of joint response under seismic excitation. The inelastic seismic response of a super element consisting of 13 one-dimensional components which represents three types of inelastic mechanisms is evaluated. Its seismic performance is assessed at reverse quasi static loading of tested reinforced concrete joint assemblage, monotonic nonlinear pushover analysis (NPA) and nonlinear time history analysis (NTHA) with results compared to the conventional approach of modeling the beam-column connection as rigid. Results from reverse quasi static loading of sub-assemblages emphasized the importance of including joint flexibility, with the super element joint model closely matching the experimental response in terms of peak shear strength, pinching behaviour and amount of hysteretic energy dissipation. NPA results of a case study hypothetical frame also revealed that including joint flexibility may lead to a reduced initial stiffness and maximum base shear when compared with the conventional approach. NTHA revealed that explicit representation of the joint region using the super element approach may not change the dominant mode of failure but however may significantly impact the estimated average drift responses. One notably observation, is the rather increased drift responses for the rigid joint modeling approach when subjected to extreme ground motion intensities, which is being attributed to the fact that framing members may be subjected to large strain hardening at such levels of ground shaking.