# Improved Shear Strength Equation for Concrete Wide Beams
## 1 Introduction  
Concrete wide beams are used in commercial facilities, parking lots, and warehouses mainly to reduce story height. The stirrup legs are normally placed around the outermost longitudinal reinforcement for shear reinforcement. A lack of shear reinforcement across the web of the beam can lead to a concentration of diagonal compressive stresses. In addition, for beams with greater width than the support, they can cause different cracking patterns due to the stress concentration in the beams. [PERSON] and [PERSON] [1] suggested that transverse reinforcement spacing should be limited to 200 mm to 400 mm depending on the shear stress. [PERSON] and [PERSON] [2] and [PERSON] and [PERSON] [3] conducted several experimental studies to investigate the stress changes in concrete beams with the same width and effective depth. [PERSON] and [PERSON] [2] reported that the interior shear legs carry a higher shear force in the transverse direction than the exterior legs in beams with multiple stirrups, and the shear stress distribution is affected by different transverse stirrup arrangements. [PERSON] and [PERSON] [3] noted that the shear stress distribution is dependent on different stirrup detailing, and the contribution of the main reinforcement can be determined by different stirrup details. They suggested that the stirrup legs should be distributed transversely across the web of beams. [PERSON] et al. [4] and [PERSON] [5] tested several wide beams with different transverse reinforcement spacing, number of legs, and support widths. Their results showed that the design codes overestimate the shear capacities of wide beams because they do not consider transverse reinforcement spacing, number of legs, or support width. [PERSON] et al. [6] tested 6 reinforced wide shallow concrete beams with diverse types ofreinforcement 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. [PERSON] 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, [PERSON] 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. [PERSON] 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. [PERSON] et al. [10] showed that macro-synthetic fibers can be used as a shear reinforcement in wide shallow beams based on experimental programs. [PERSON] et al. [11] performed the test on 16 full-scale specimens.