To calculate the shear capacity of structural members reinforced with fiber-reinforced polymer (FRP), current shear design provisions generally use slightly modified versions of existing semiempirical shear design equations initially developed for steel reinforced concrete beams. Such methods generally assume that the traditional approach of superimposing concrete contribution to shear, Vc to that of stirrups, Vs can also be used to calculate the nominal shear capacity, Vn of FRP-reinforced concrete beams provided that the axial rigidity of FRP longitudinal bars and the capacity of FRP stirrups at the bent portions are accounted for. These methods also noticeably vary in the manner they account for the effect of basic shear design parameters on shear strength. This paper presents simple yet improved equations to calculate the shear capacity of FRP-reinforced concrete beams based on the genetic algorithms approach. The performance of the proposed equations is compared to that of four commonly used shear de...

Corrosion of concrete sewer pipes by sulfuric acid attack is a problem of global scope, leading to multibillion dollar losses each year. However, research is still needed to better understand the mechanisms of sulfuric acid attack on concrete and the related effects of concrete mixture design parameters. In this paper, the combined effect of wetting-drying cycles and concrete mixture design parameters including cement content, water/cement (w/c) ratio, and coarse aggregate content on the resistance of concrete to sulfuric acid was investigated. Specimens from various concrete mixtures were soaked in sulfuric acid solutions with pH of 0.3, 0.6, 1.0, 1.5, 2.0, 2.5, and 3.0. The mass loss of concrete specimens due to immersion in sulfuric acid and wetting-drying cycles was used as a measure of concrete degradation. For specimens that experienced no mass loss due to low concentration of sulfuric acid, the thickness of the gypsum layer that formed on specimens’ surface was measured on thin sections using trans...