Size effect in shear for fiber reinforced concrete members

点击翻译按钮获取中文摘要

Considerable research has established a size effect in shear for reinforced concrete members without web reinforcement, where the shear stress at failure decreases with an increase in the member depth and/or a drop in the aggregate size. Research has also shown a decrease in the shear capacity for members constructed with lightweight aggregates and, for high strength concrete. The addition of steel or polymeric fibers into the matrix will help reduce crack widths, control crack spacing and provide an alternate shear force transfer mechanism. These benefits are expected to mitigate size effects in shear for fiber reinforced concrete (FRC) in comparison with similar members without fibers. The proposed project will develop several normal and high strength concrete mixes with and without fibers, using locally available cements and aggregates. Size effects will be examined for the constitutive response of FRC in compression, indirect tension, and direct shear. Using selected mixes, shear-critical beam specimens without conventional web reinforcement will be studied to characterize member response in shear, building upon the material models developed earlier. In each phase of this study, geometrical scale factor of 1:4 (or higher) will be used to assess the size effect. The results will be analyzed to develop analytical models and design guidelines for FRC members subjected to flexure and shear. This study will be conducted at the University of Alberta, in collaboration with the Cement Association of Canada and NSERC Canada.