A stochastic model for the capacity estimation of non-seismically designed beam-column joints

Abstract

An analytical model based on nonlinear fracture mechanics was employed to evaluate the shear capacity of a substandard beam-column joint retrofitted by externally applied post-tensioned bars. The strength of the reference specimen was predicted as the capacity of plain concrete under tension with microcracks in the fracture process zone smeared over a band - i.e. crack band theory. Crack minimization effects in the specimens retrofitted by post-tensioned bars were considered by strain energy stored in the bars per unit fracture surface area. Due to the inherent uncertainty in material constitutive laws, the analytical model was evolved to a stochastic level to propose a more advanced model for estimating the capacity. It is found that the experimental results were within the prominent range of Probability Density Functions (i.e. mean ± one standard deviation) of the estimated joint tensile stress