Behavior of Damaged Lightweight reinforced Concrete Wide Beams with Near Surface Mounted GFRP Bars under Monotonic and Repeated Loadings
Received: 5 April 2025 | Revised: 21 April 2025 and 28 April 2025 | Accepted: 4 May 2025 | Online: 4 June 2025
Corresponding author: Tamara Alaa Khalaf
Abstract
This study investigates the use of Near Surface Mounted (NSM) Glass Fiber Reinforced Polymer (GFRP) bar strengthening and their contribution to flexural strength for damaged lightweight Reinforced Concrete (RC) wide beams under monotonic and repeated loads. The experimental program consists of casting and testing twenty RC wide beams, including two reference wide beams without any GFRP strengthening and eighteen strengthened wide beams. The twenty beams were divided into two main groups, monotonic and repeated loading. The primary variables which have been chosen include the percentage of damage (0%, 50%, and 65%) from the ultimate load of reference beam, the number of GFRP bars, and the reinforcement ratio of GFRP bars. The results indicate that, all strengthened beams have greater ultimate strength than the reference un-strengthened beam in repeated loads, where the increase ranged from 23.8% to 68% for the beam with a damage percent of 65% and 2 Ø12 mm GFRP bars and the beam with a damage percent of 0% and 3 Ø16 mm GFRP bars, respectively, concerning the reference un-strengthened beam. The ratio of repeated ultimate load to monotonic ultimate load ranged from 0.91 to 0.95. The findings indicate that the ultimate load capacity of lightweight wide beam specimens under repeated loading was lower than that observed under monotonic loading. This discrepancy may be attributed to concrete deterioration, which occurs because of the development of internal cracks in the concrete throughout the loading and unloading process. Furthermore, the bond between concrete and steel deteriorates more significantly under repeated stress due to increased dissociation.
Keywords:
GFRP bars, near surface mounting, damaged beam, lightweight concrete, damaged wide beamDownloads
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