Title: Ledge behavior and strength of short-span L-shaped beams
Date Published: March-April 2018 
Volume: 63 
Issue: 2
Page Numbers: 67-86
Authors: Mohamed K. Nafadi, Omar M. Khalafalla, Gregory W. Lucier, Sami Rizkalla, Paul Zia, and Gary J. Klein
https://doi.org/10.15554/pcij63.2-04

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Abstract

The design procedure for ledges of L-shaped beams presented in the seventh edition of the PCI Design Handbook: Precast and Prestressed Concrete has been called into question by many engineers and researchers. Research findings from previous experimental studies have indicated that the ledge design equations provided in the seventh edition of the PCI Design Handbook overestimate the ledge punching-shear capacity. This paper presents the findings of the first phase of a comprehensive experimental program conducted with the objective of developing design guidelines for the ledges of L-shaped beams. In this first phase of study, short-span beams were used to minimize the effect of global stresses and the cost of testing, thus allowing for a larger number of parameters to be examined. The main objectives of this study were to investigate the ledge behavior and the configuration of the failure surface. In addition, the study also investigated the effect of various parameters believed to affect ledge behavior. The study also investigated the performance of special reinforcement details toward the development of detailing recommendations for ledge reinforcement. Research findings indicate that even with low levels of global stress, the ledge design procedure provided in the seventh edition of the PCI Design Handbook could overestimate the ledge capacity. Furthermore, the observed failure surface was generally larger than the assumed surface specified by the PCI procedure. The study also found that several parameters affected the ledge capacity but are not considered by the PCI procedure. Finally, the study also demonstrated that certain reinforcement details can be used to improve the ledge behavior and to enhance the ledge capacity.

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