SEISMIC BEHAVIOUR OF BEAM-COLUMN SUB-ASSEMBLAGES DESIGNED FOR TWO LEVELS OF GRAVITY LOADS

Abstract

An exterior jointof a typical three storied three bay reinforced concrete (RC) Framed building isconsidered forthe study. The frameisdesigned for the combination of dead load and live loads. Depending on the load level, there is a possibility of providing either singly reinforced (SP1) or doubly reinforced (SP1-D) section for beams at the joint. For gravity load designed specimens which require singly reinforced section for beams, bottom reinforcement bars are curtailed as required. For higher gravity designed specimens which require doubly reinforced section for beam, bottom reinforcement bars are to be provided with required anchorage beyond the face of the column.The beam-column sub-assemblages designed for two levels (normal and higher) are subjected to seismic type of loading and load-displacement hysteresis, energy dissipation, strength and stiffness degradation of the specimens are compared. The cumulative energy dissipation of specimen SP1-D is 37% higher than that of SP1.The specimens SP1-D and SP1 have shown almost same level of stiffness degradation in negative cycles. In positive cycle, SP1 have undergone more stiffness degradation than SP1-D.The maximum strength degradation of SP1-D and SP1 in positive cycles is found to be 37% and 34% respectively. In negative cycles, maximum strength degradation is 29%, and 23% respectivelyfor SP1-D and SP1. Keyword: Beam-column sub-assemblage, Gravity load designed, Energy dissipation, Strength degradation, Stiffness degradation, Hysteresis