Abstract
Loading test of RC deep beams with solid circular cross section having a/d=1.0 under simply supported and anti-symmetric moment was carried out and shear failure behavior was investigated. As a result, it was confirmed that a compression strut forms between opposing corners of span under anti-symmetric moment and shear capacity decreases compared to that under simply supported condition. Longitudinal bars arranged around the cross section increases the shear capacity regardless of the supporting condition as well as observed in beams of rectangular cross section. The existing prediction equation for RC deep beams of rectangular cross section underestimates the shear capacity under simply supported condition, while it can properly predict the shear capacity under anti-symmetric moment by using total length of a span for shear span length. In addition, it was revealed that the effect of shear reinforcements under simply supported condition is provided by the confinement effect of concrete, while that under anti-symmetric moment is provided by a combination of confinement effect and the shear resisting force at a diagonal crack.
