Analytical investigation on shear failure mechanism of RC T-beams with stirrups

Reinforced concrete T-beam is widely used in civil engineering structures and buildings. However, the evaluation method based on the shear resistance mechanism considering the effects of the top fange area has not been established in current structural design codes. The purpose of this study is to clarify the shear failure mechanism of RC T-beams with stirrups. The shear failure behaviours of the RC T-beams were investigated numerically with a three-dimensional nonlinear finite element method in which the width of the top flange, shear reinforcement ratio were varied. As a result, increasing in flange width of T-beam gives higher shear capacity with nonlinear relationship. The principal strain distribution and stirrups strain development of T-beams were different from the rectangular beam. In T-beams, the average shear stresses of web area in top flange were almost the same at the ultimate state, regardless of the flange width. In addition, the effect of shear reinforcement with respect to the increase of the average shear stress in fange area was not observed. The RC T-beam has a unique shear failure mechanism which is caused by T-shape cross-section and the horizontal crack.