Shear Behavior of Beams without Transverse Reinforcement

摘要

To deepen the understanding of shear behaviour in beams without transverse reinforcement, the relative importance of two major contributing elements to concrete shear resistance(V_c), such as the friction at crack faces and the residual tensile stresses between cracks, was explained by comparing two analytical methods based on the truss model concept. One is called "the Modified Compression Field Theory(MCFT)" considering the two elements explicitly, and the other "the Crack Friction Truss Model(CFTM)" more dominantly the former element in determining the concrete shear resistance. To evaluate their validity in considering such complex behaviour, the predictions were also made for twenty KAIST beam tests, designed more likely to the development of the size ffect law based on the fracture mechanics concept. Experimental findings with varying of shear span-to-depth(a/d) and longitudinal reinforcement (rho_t) ratios, and beam depths were well captured by the two methods, and the complete analysis results obtained from the MCFT enabled additional explanations that were difficult to measure in tests. In addition, the simplified V_c+V_s approach, but including the empirical factor to reflect the size effect, predicted test results with reasonable accuracy.