Code Provisions for Shear Strength in Prestressed FRC Members: A Critical Review

Since its introduction, FRC has gained quite high attention from precast industry for the potential advantages resulting from partial or total removal of conventional reinforcement, especially related to shear. As compared to non-prestressed elements, the use of precompression may allow to significantly reduce the required amount of transversal reinforcement, taking advantage of the shear force carried by prestressing tendons/cable. As proved by several research studies, the adoption of fibers may further reduce shear reinforcement, which could be only limited to support areas or to those regions where the prestressing action is not fully developed. The current structural codes are generally very conservative in predicting the shear strength of these elements. Therefore, new research studies are needed to improve the accuracy of models for calculating the shear strength. Special focus could be also done to existing prestressed structures, which might benefit from more refined models in terms of reduction of structural repairing costs. This paper presents a database of shear tests of prestressed FRC members, emphasizing the rather conservative predictions of the prEN 1992-1-1 (2020) and fib Model Code 2020 drafts. A critical discussion will follow