Comparative Assessment of Shear Demand for RC Beam-Column Joints under Earthquake Loading

Abstract

This paper focuses on the evaluation of bi-axial shear demand for reinforced concrete (RC) beam–column joints assuming: (i) the SPEAR frame as a benchmark; and (ii) different structural analysis methods which share the same seismic input. A numerical model was implemented using lumped plasticity. The joints were modeled as rigid offsets of beams and columns. The shear demand at a joint is evaluated as a post-process of the beam’s nodal moment. The discussion focuses on the differences between the estimated shear demand considering modal-response-spectrum analysis (MRSA), non-linear static analysis (NLSA) and non-linear time history (NLTH). Strength assessment of joints is discussed as well. Significant strength differences were recognized by using different building codes targeted to existing structures which, in general, behaved on the safe side. The elliptical shear strength domain resulted in being conservative when compared to NLTH shear demand orbits. NLSA, using modal combination, proved to estimate the larger shear demand with respect to MRSA and NLTH.