Improved Shear Strength Equation for Concrete Wide Beams

Abstract

Featured Application: This study provides a reasonable method to predict shear strength for concrete wide beams.Abstract: An improved shear strength equation is proposed that considers transverse reinforcement spacing and support conditions for concrete wide beams. Eighteen specimens were fabricated to examine the influence of transverse reinforcement spacing, the number of transverse shear reinforcement, and support width on shear capacity. From the test results, a shear strength equation is proposed and used to evaluate the shear strength of 23 specimens from previous studies and 18 from this study. For the 41 specimens, the proposed shear strength equation results had a mean of 1.16 and a standard deviation of 0.16. It showed that the proposed shear strength equation can predict shear strength reasonably well for concrete wide beams. Appl. Sci. 2019, 9, 4513 2 of 15 reinforcement to investigate the effectiveness of various types of shear reinforcement in improving the shear capacity of wide beams. The results showed that independent bent-up bars increased the shear capacity and ductility of wide beams. The combination of bent-up bars with stirrups can achieved higher shear capacity and gradual failure of wide beams. Conforti et al. [7] conducted shear tests on 14 wide shallow beams with different widths and depths to evaluate shear performance. The experimental results indicated that wide shallow beams with width-to-effective depth ratio from 2 to 3 enhanced shear behavior, and shear equations of current codes do not consider the extra resistance in shear of wide shallow beams. Also, Conforti et al. [8] evaluated the influence of width-to-effective-depth ratio (b/d) and reinforcement spacing-to-effective depth ratio on the shear behavior of reinforced concrete beams without the web reinforcement. The experimental results showed that for b/d > 1, an increase in the b/d determines a non-negligible increment in the shear strength whereas the s/d does not affect the capacity. Khalil et al. [9] analyzed effect of the beam width-to-depth ratio and the column width-to-beam-width ratio. The test results presented that although the beam-width-to-depth ratio and support width has significant influence on shear performance, the predictive equations for shear strength did not take those effect into consideration which leads to a major error in estimating the shear strength of wide shallow beams. A modified formula was proposed to predict the effective width accurately based on statistical procedure.In addition to evaluating the effect of design parameters on the shear capacity for concrete wide beams, recent studies have been conducted to add fiber to concrete. Several authors have performed experiment to determine the shear contribution provided by polypropylene fibers in slender beams. Conforti et al. [10] showed that macro-synthetic fibers can be used as a shear reinforcement in wide shallow beams based on experimental programs. Navas et al. [11] performed the test on 16 full-scale specimens. The results indicated ...

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