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Title: Shotcrete Modification Factors for the Development Length Equation

Author(s): Pasquale Basso Trujillo, Marc Jolin, Bruno Massicotte, and Benoît Bissonnette

Publication: Structural Journal

Volume: 118

Issue: 3

Appears on pages(s): 305-314

Keywords: bond strength; development length; encapsulation; fuzzy number; modification factor; possibility theory; shotcrete; sprayed concrete; voids

DOI: 10.14359/51730539

Date: 5/1/2021

The development of design criteria intended for reinforced shotcrete structures has become a pressing matter for the industry. This is particularly true when imperfections behind reinforcing bars might be created during spraying operations. Current guidelines categorize imperfections qualitatively and only address the inspection of shotcrete for quality control purposes. Moreover, they disregard the bar-concrete bond strength as a function of the bars’ encapsulation quality limiting their usefulness for structural engineers wanting to rightfully include shotcrete in the design. In this paper, data from bond specimens with varying reinforcing bar encapsulation qualities was used to derive modification factors for the development length equation of straight bars. The modification factors were computed as bar stress ratios between perfectly encapsulated bars and those having imperfections using notions of possibility theory. As such, modification factors can be selected based on the void size and an equal bar stress probability associated to a building’s risk category.