Abstract
Deep beams are commonly used in tall buildings, offshore structures, and foundations. According to many codes and standards, strut-and-tie model (STM) is recommended as a rational approach for deep beam analyses. This research focuses on the STM recommended by ACI 318-11 and AASHTO LRFD and uses experimental results to modify the strut effectiveness factor in STM for reinforced concrete (RC) deep beams. This study aims to refine STM through the strut effectiveness factor and increase result accuracy. Six RC deep beams with different shear span to effective-depth ratios (a/d) of 0.75, 1.00, 1.25, 1.50, 1.75, and 2.00 were experimentally tested under a four-point bending set-up. The ultimate shear strength of deep beams obtained from non-linear finite element modeling and STM recommended by ACI 318-11 as well as AASHTO LRFD (2012) were compared with the experimental results. An empirical equation was proposed to modify the principal tensile strain value in the bottle-shaped strut of deep beams. The equation of the strut effectiveness factor from AASHTTO LRFD was then modified through the aforementioned empirical equation. An investigation on the failure mode and crack propagation in RC deep beams subjected to load was also conducted.
Highlights
Deep beams are mainly used in tall buildings, offshore structures, and foundations [1]
The present study examines the strut-and-tie model (STM) that ACI 318–11 and AASHTO LRFD recommended and uses experimental results to modify the strut effectiveness factor for reinforced concrete (RC) deep beams
Six RC deep beams with different a/d ratios were tested until failure
Summary
Deep beams are mainly used in tall buildings, offshore structures, and foundations [1]. Based on many codes and standards, the strut-and-tie model (STM) is recommended as a rational approach for analyzing and designing reinforced concrete deep beams [2,3,4,5,6,7,8]. The concepts of the STM are originally referred to truss analogy proposed by Ritter [9] and Mörsch [10] as well as compression field theory proposed by Michael P.Collins [11] for the design of shear structural elements. The truss model was brushed up by Schlaich et al and proposed for consistent design of reinforced concrete structures [12]. Since 2002, ACI building code has PLOS ONE | DOI:10.1371/journal.pone.0130734. Since 2002, ACI building code has PLOS ONE | DOI:10.1371/journal.pone.0130734 June 25, 2015
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