Available online at www.CivileJournal.org Civil Engineering Journal (E-ISSN: 2476-3055; ISSN: 2676-6957) Vol. 9, No. 06, June, 2023 1389 Behavior of Centrifuged GFRP Poles Under Lateral Deflection Youssef A. Awad 1, 2 , Ahmed M. EL-Fiky 2 , Hosam M. Elhegazy 1, 3* , Mahmoud G. Hasan 2 , Ibrahim A. Yousef 2 , Ahmed M. Ebid 1 , Mohamed A. Khalaf 2 1 Department of Structural Engineering and Construction Management, Future University in Egypt, Egypt. 2 Structural Engineering Department, Faculty of Engineering, Ain Shams University, Cairo 11517, Egypt. 3 Postdoctoral Researcher, School of Construction Management Technology, Purdue University, West Lafayette, IN, United States. Received 12 March 2023; Revised 15 May 2023; Accepted 19 May 2023; Published 01 June 2023 Abstract Centrifugal-manufactured GFRP pipes are widely used today as lighting and low-power transmission poles due to their lightweight, high electrical insulation, low cost, and corrosion resistance. Despite these advantages, GFRP poles suffer high deflection problems due to their low elastic and shear moduli values. In order to overcome this disadvantage, three techniques were suggested to control the lateral deflection of the GFRP poles: an extended internal steel stub, external steel angles, and internal steel bracing bars. The main objective of this study is to determine the optimum strengthening technique to improve the serviceability of GFRP poles in terms of lateral deflection according to ASTM D4923. An experimental research program containing five full-scale GFRP poles was carried out to determine the optimum strengthening technique and the effect of connectors opening near the base and compare it to previous research. The results indicated that flexural stiffness was increased by 44%, 66%, and 38% for the extended stub, steel angles, and bracing bars, respectively. Besides that, the reduction in flexural stiffness due to connector opening was about 8%. The measured deflections showed good matching with simplified mathematical calculations, and the division was about ±10%. The external steel angle technique showed the best efficiency in Stiffness behavior. Keywords: GFRP Poles; Deflection Control; Stiffness; Improving Serviceability. 1. Introduction Fiber-reinforced polymer (FRP) is a great substitute because it has fewer disadvantages, such as the quick deterioration of wood, the heavy weight of reinforced concrete poles, the short lifetime of aluminum, and steel corrosion, which makes treating these materials uneconomical. Electric poles and transmission networks are one type of essential infrastructure. Compared to other materials like steel and aluminum, FRP offers various benefits that make it a suitable material for transmission and distribution poles, towers, H-frames, and light poles [1]. The primary benefits of GFRP over traditional steel for meteorological towers are their high strength-to-weight ratio and ability to resist corrosion. Although FRP composites have been used in various applications for more than 50 years, other materials, including steel, wood, and aluminum, have been used for far longer [2]. Transmission poles and towers made of Glass Fiber Reinforced Polymer (GFRP) have been investigated for their durability in severe temperature and UV conditions. UV rays and adverse temperature circumstances have an impact on the performance of GFRP material; as a result, the elastic modulus increases, its strength decreases, and a little shift in Poisson's ratio takes place [3]. In addition to serving as force-bearing components of towers, glass fiber-reinforced plastic (GFRP) poles may be utilized to construct transmission towers and bridge structures and to support transmission lines in place of conventional steel arms [4]. In European nations, glass fiber-reinforced polymer (GFRP) utility poles are becoming more prevalent. Therefore, in order * Corresponding author: hossam.mostaffa@fue.edu.eg http://dx.doi.org/10.28991/CEJ-2023-09-06-07 © 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/).