Available online at www.CivileJournal.org Civil Engineering Journal (E-ISSN: 2476-3055; ISSN: 2676-6957) Vol. 9, No. 04, April, 2023 835 Shear Performance of GFRP Reinforced Concrete Beams with Seawater and Chopped Fiber Waleed Abdallah 1 , Abdelrahman M. Farrag 1* , Ahmed F. Deifalla 2 , Amal. H. Ibrahim 1 , Hamdy M. Mohamed 1 , Ahmed H. Ali 1 1 Department of Civil Engineering, Faculty of Engineering, Helwan University, Cairo 11382, Egypt. 2 Structural Engineering and Construction Management Department, Future University in Egypt, Cairo 11835, Egypt. Received 11 January 2023; Revised 06 March 2023; Accepted 19 March 2023; Published 01 April 2023 Abstract This paper reports an experimental study on the behavior and shear strength of concrete beams reinforced with longitudinal GFRP bars mixed with sea water. In order to evaluate how much concrete contributes to shear resistance, seven beams were tested in bending. Similar in size and concrete strength, the beams were longitudinally reinforced with glass fiber- reinforced polymer bars; however, they did not even have shear reinforcement. The beams, which measured 3,100 mm in length, 400 mm in depth, and 200 mm in width, were conducted and tested up to failure. The test variables were longitudinal reinforcement ratios (1.0, 1.4, and 2.0%), chopped fiber content (0, 0.5, 2, and 3 kg/m 3 ), and mixing water type (freshwater and seawater). The test findings showed that increasing the reinforcement ratio increased the neutral-axis depth and allowed the formation of more closely spaced fractures while decreasing the loss of flexural stiffness after cracking. By increasing the area of concrete in compression, this in turn enhances the contribution of aggregate interlock as well as the contribution of uncracked concrete. Furthermore, increasing the reinforcement ratio improves the dowel action, which reduces the tensile stresses that are created in the concrete around it. Keywords: Seawater; Chopped Fiber; Fiber-Reinforced Polymer (FRP); Shear Strength. 1. Introduction Increasingly global concerns about the accumulation of construction and demolition waste and the deterioration of reinforced concrete (RC) structures due to steel corrosion impose the need to use alternative "greener" materials to achieve more efficient and sustainable RC structures. Beams are usually reinforced with shear reinforcement to prevent shear failures. Due to the labor cost associated with reinforcement installation, shear reinforcement is usually expensive. Noncorrosive fiber-reinforced polymer (FRP) reinforcing bars are becoming more frequently used in place of steel reinforcing bars in a variety of applications, including marine construction, parking buildings, and bridges [1]. Additionally, in the field of tunnel excavation, the usage of glass-FRP (GFRP) bars and spirals in soft-eyes is growing in popularity in North America. Numerous studies looking into the contribution of concrete to the overall shear capacity of FRP concrete structures have been conducted recently. The experimental work has focused mainly on beams with rectangular cross sections mixed with fresh water [1 –4]. Accordingly, many models have been put forward to calculate shear capacity, most often based on a statistical curve fit to experimental beam test results [5]. In addition, several guidelines and standards have been published, including empirical formulae for assessing the concrete shear contribution [6–9]. * Corresponding author: abdelrahman.magdy@buc.edu.eg http://dx.doi.org/10.28991/CEJ-2023-09-04-05 © 2023 by the authors. Licensee C.E.J, Tehran, Iran. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC-BY) license (http://creativecommons.org/licenses/by/4.0/).