The Punching Shear Behavior of Self-Compacted Reinforced Concrete Two-Way Slabs with Openings and Strengthened by CFRP Sheets
Received: 22 July 2025 | Revised: 5 September 2025 | Accepted: 15 September 2025 | Online: 18 October 2025
Corresponding author: Ali Al-Balhawi
Abstract
The use of Fiber Reinforced Polymers (FRP) is a common technique for strengthening and rehabilitating a wide range of Reinforced Concrete (RC) structures. The structural members often include openings to accommodate passages for services, such as pipes and electrical wiring. The openings in structural members, such as two-way slabs, reduce their structural performance. This reduction can be overcome through the use of Carbon Fiber Reinforced Polymer (CFRP) sheets. This experimental study investigates the punching shear behavior of Self-Compacted Reinforced Concrete (SCRC) two-way slabs with square openings and strengthened with CFRP sheets in a square configuration. The experimental program consisted of five RC slabs, each measuring 1000 mm × 1000 mm × 75 mm, reinforced with the same steel ratio. Three numbers of CFRP layers were considered in this study (one, two, and three). Two reference specimens were used: one with a square opening, while the other was a solid slab. The results indicate that the proposed technique is unable to recover the full load capacity compared to the solid slab, but it improves the performance of the unstrengthened slab with a square opening. This improvement was evident in terms of the first crack load, ultimate load, and stiffness. The use of one, two, and three layers of CFRP sheets increased the first cracking load of slabs with openings by 25.304%, 41.783%, and 40.498%, respectively, compared to the unstrengthened slabs. The enhancement ratios for the ultimate loading were 19.164%, 21.033%, and 22.930%, respectively, for the same slabs.
Keywords:
two-way slabs, CFRP sheets, deflection, strengthening, CFRP layers, FRP, concreteDownloads
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