Effect of prestress levels on flexural and debonding behavior of reinforced concrete beams strengthened with prestressed carbon fiber reinforced polymer plates

Abstract

This study is focused on the effect of the prestress level of fiber-reinforced polymer reinforcement on the flexural and debonding behavior of strengthened beams. A total of seven reinforced concrete beams were used in the bending test. A carbon fiber reinforced polymer plate was used as the fiber-reinforced polymer reinforcement. Test variables included various prestress levels and the use of anchorage systems. The specimens were comprised of one control beam, one bonded non-prestressed carbon fiber reinforced polymer-strengthened beam, and five bonded prestressed carbon fiber reinforced polymer-strengthened beams. The deflection-controlled three-point bending test was conducted on all beams until failure. The failure of the beam with an externally bonded carbon fiber reinforced polymer plate was attributed to the debonding of the carbon fiber reinforced polymer plate. The failure mode of beams with bonded prestressed carbon fiber reinforced polymer plates was a two-stage debonding, which was followed by the rupture of the carbon fiber reinforced polymer plates; thus, the behavior of the prestressed beams changed to the unbonded state because of the anchorage system. The cracking, yield, and debonding loads of prestressed beams increased as the prestress level of the carbon fiber reinforced polymer plate increased. However, the effect on the deflection corresponding to these loads was not significant. Also, the ultimate load was constant regardless of the prestress level, except for the case of the 70% prestressed beam, but the effect on ultimate deflection was significant. The recommended appropriate prestress level in securing the ductility of a strengthened beam was 40% or less of the tensile strength of the carbon fiber reinforced polymer plate.

Experimental Study of Flexural Behavior of Reinforced Concrete Beam Strengthened with Prestressed Textile-Reinforced Mortar

“…These factors occur as a result of various changes in the external environment, such as the increased service life and climate change. Substantial financial resources are required in repairing and strengthening the performance and durability of structures [1], and several researchers have investigated various repair/strengthening methods [2][3][4][5][6]. The textile-reinforced mortar (TRM) method is a structural strengthening method that involves producing textiles with an excellent tensile strength and chemical resistance, such as carbon, alkali-resistant-(AR-) glass, aramid, and basalt fiber, and attaching these materials onto the surface of the concrete structure using mortar, an inorganic material [7].…”

Experimental Study on Flexural Behavior of TRM-Strengthened RC Beam: Various Types of Textile-Reinforced Mortar with Non-Impregnated Textile

“…Moreover, with the development of design code, structures are required to be strengthened to meet structural safety [2]. To keep up with these requirements, fiber-reinforced polymer (FRP) strengthening method has been studied and applied for many years [3][4][5]. Strengthening with FRP uses organic materials such as epoxy resin for bonding with concrete substrate.…”

Investigation of Strain of Steel Reinforcement of Modular Flexural Member at Discontinuity Interface

“…This affects the safety of structures; thus, the performance of infrastructures needs to be improved. Accordingly, various maintenance methods for structures have been proposed [1][2][3], and repair and strengthening methods, such as fiber-reinforced polymer (FRP) and textiles, have been proposed and applied [4][5][6][7].…”