Influence of diagonal reinforcement with spiral stirrps on shear capacity of coupling beam in shear wall

Abstract

Concrete core-walls are penetrated by vertical families of openings for doors to stairs, lifts and other spaces. These openings separate the core as a whole into a number of sub-cores linked by coupling-beams being the residual strips of concrete core-wall above and below openings. The (span/depth) ratio of these beams is determined by non-structural considerations and usually well into the ‘deep beam’ range prone to brittle behavior. This paper presents the results of tests of three coupling beam specimens in which the influence of three types of shear reinforcement were studied. All specimens were of the same dimensions and provided with different types of shear reinforcement. In order to investigate the contribution of various types of shear reinforcement, one specimen was provided with diagonal bars confined by spiral stirrups, and the second one provided with diagonal bars without stirrups, and the third one provided with the steel plate. All fixed vertically from one side and let the second side free to the top and the load was applied to the top portion of coupling beam. The performances of coupling beam were measured in terms of crack development and drifts, failure mode and ultimate load. The results of the coupling beam reinforced with diagonal bars and spiral stirrups showed high resisting of shear capacity comparing with other specimens, and coupling beam with diagonal reinforcement only showed high performance same as to that with spiral stirrups, and the third specimen of coupling beam with steel plate showed weak performance to dissipate the shear stresses.