Seismic behavior of reinforced concrete column-steel beam subassemblies and frame systems

In this paper, results are presented from tests of four reinforced concrete (RC) column-steel beam (RCS) subassemblies under large displacement reversals and dynamic analyses of RCS systems under various ground motions. The test specimens were designed following a strong column-weak beam philosophy and a deformation-based capacity design method for the connections. The effect of joint deformations on overall behavior of RCS frame systems was studied through a series of inelastic dynamic analyses performed on a six-story RCS frame with various joint modeling and design parameters. Results from this research show that RCS frame systems perform satisfactorily under seismic excitations. The test specimens showed a good strength and stiffness retention capacity with excellent energy dissipation up to displacement levels of approximately 5.0% drift. The joint deformation-based capacity design procedure was effective in controlling damage in the connection region, and thus forcing most of the inelastic activity to concentrate in the beam ends. From the analytical studies, it was found that joint deformations have a significant influence on maximum interstory drift of RCS frames. For the ground motions considered, an increase of up to 35% in maximum story drift was obtained when connection flexibility was considered in the analyses.