Study on size effect of RC and rehabilitated exterior beam-column connections under cyclic loading

Abstract

Beam-column connection is one of the vital structural parts, whose behaviour during earthquake is very critical. An experimental programme was undertaken by considering three types of exterior RC beam-column connections with three different sizes of geometrically similar specimens in each type. The specimens were tested under displacement-controlled cyclic loading. Depending on the level of damages, rehabilitation strategies were applied appropriately. The studies were repeated for all the rehabilitated specimens and observed that the rehabilitated specimens could successfully restore their load-carrying capacity. Further, the experimental results from specimens of different sizes revealed the existence of a significant size effect, which could approximately be described by the size effect law previously proposed by Bažant. The size effect was further observed to be more prominent with the increase in brittleness of specimens. Energy dissipation per unit volume (eN) of the D-region was also correlated with drift angle for different specimen sizes. The variation of ultimate stress with relative deflection was also studied. The nominal principal tensile stresses were evaluated at the beam-column connections for all the specimens. It was observed that eN as well as variation of stress with relative deflection and magnitudes of nominal principal tensile stresses also exhibited the existence of size effect.