Скачать или смотреть Concrete Break-Out Failure of Hooked and Headed Bars in RC Column Joints

Presented By: Giovanni Muciaccia, Politecnico di Milano

Description: The issue of development length (ldh) of steel bars (hook and headed) in Reinforced Concrete 20 (RC) beam-column joint is addressed. In the context of ACI-318, ldh is empirically expressed as a function of the yield strength of the reinforcement, the compressive strength of the concrete and the bar diameter. Additional modifications factors consider the occurrence of different boundary conditions such as light-weighted concrete, epoxy coating, confining reinforcement. Such formulation is based on an experimental characterization which identified three potential mechanisms: (i) concrete-break out failure (CB); (ii) joint-shear failure (JS); (iii) pullout/splitting failure (PO). However, there is poor agreement on what CB is, even as far as 2 the meaning of that term itself is concerned. In this paper, results of non-linear finite element analyses are used to assess the mechanical behavior of selected experimental tests. In some cases what was originally defined as CB failure reveal to be JS failure. For the sake of completeness, numerical results are compared to simple analytical expressions.