Experimental Study on Flexural Behavior of Prestressed Concrete Beams Reinforced by CFRP under Chloride Environment

Abstract

In order to study the effects of initial damages, CFRP reinforcement, and chloride corrosion on the flexural behavior of prestressed concrete beams, ten prestressed concrete beams were designed and manufactured, which were preloaded with 0%, 40%, and 60% of the ultimate load to crack. Then, part of the beams were reinforced by CFRP and immersed in chloride condition for 120 days. After that, the four-point bending tests were performed. Then, the sectional strain, deformation, flexural stiffness, flexural capacity, ductility, and the cracking characteristics were researched. The test results demonstrate that the sectional strain of PC beams still follows the plane cross section assumption after a pure bending deformation considering of the initial cracks, chloride corrosion, and CFRP reinforcement. The initial damage accelerates the chloride corrosion, resulting in the loss of initial stiffness, ductility, and cracking load, and the reduction in flexural capacity is less than 10%, and the failure modes of these beams are prone to change from concrete crushing to shear failure. In the cracking stage, the reinforcement of CFRP inhibits the bending deformation, leading to the reduction in stiffness degradation rates and the increase of cracking load, and the ultimate load increases by 12.8%∼18.7%. The reinforcement of CFRP constrains the development of cracks, increases the cracks numbers by 50%∼130%, decreases the cracking rates of beam bottoms by 52.5%, and reduces the average crack widths by 65.8% at 195 kN. It can be seen that the reinforcing effect of CFRP is more significant compared with the weakening effect of short-term chloride corrosion and initial damage on the flexural behavior.

Residual Flexural Capacity of Corroded Prestressed Reinforced Concrete Beams

“…The studies are grouped in order to clearly distinguish the members subjected to different corrosion processes (natural or accelerated). Among them, four articles [29][30][31][32] dealt with the behavior of beams extracted by a decommissioned bridge (DB_N); three works [33][34][35] investigated the performance of beams with reduced dimensions with respect to the previous ones and subjected to a naturally corrosive environment (B_N); eleven papers [36][37][38][39][40][41][42][43][44][45][46][47] experimentally tested the flexural performance of PRC beams damaged by artificial corrosion (B_A). • ∆R max *** ∼ = 50% for the beam with some wire cross-section loss up to 75%.…”

“…Liu et al [45] conducted experimental testing on five PRC beams using four-point bending. A very low initial prestressing action of 558 MPa, only 0.30 times the nominal strand yield strength, was applied.…”

“…More recently, the Polcevera Viaduct in Genoa, which was in service for over 50 years, collapsed, likely due to the combined effects of corrosion and fatigue [23][24][25]. Although scientific efforts are being devoted to the assessment of the residual structural performance of prestressed RC members damaged by corrosion [26][27][28], few experimental studies have been conducted to explore the flexural behavior of corroded pretensioned reinforced concrete (PRC) beams [29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47]. The beams realized with the pretensioning technique, where the strands are adherent to the concrete, respond differently to the corrosion phenomenon with respect to the case of beams realized with the post-tensioning technique [38,48].…”

“…µ was progressively reduced by increasing the corrosion degradation. Concerning the artificially corroded PRC beams, nine papers [36][37][38][39][40][41][42][43][44][45] experimentally investigated the flexural performance decay under monotonic loads (B_A_M); with the aim of investigating the beneficial effects of retrofitting intervention by means of composite materials, two works [39,41] also address the issue of the structural response of corroded PRC beams (RB_A); only one article [39] deals with both monotonic and cyclic flexure behavior (B_A_C); two papers [46,47] investigate the fatigue performance of corroded PRC beams (B_A_F). In the following, the prominent key findings of this research are summarized with specific reference to the results obtained for the flexural performance of corroded beams.…”

Experimental Study on Flexural Capacity of Corroded RC Slabs Reinforced with Basalt Fiber Textile

“…In recent years, the research and application of retrofitting and rehabilitating concrete structures with carbon fiber-reinforced polymer (CFRP) has developed incrementally and rapidly [2,3]. A number of studies have shown that the application of CFRP as an external strengthening system would effectively increase the ultimate loading carrying capacity and flexural stiffness of corroded RC beams [4][5][6][7][8][9], but the shortcoming lies in the significant reduction in the deflection capacity of beams and their ductility [10]. Meanwhile, some problems have emerged with the usage of externally bonded CFRP composites, including high cost, poor high-temperature resistance, no waterproofing of surfaces, incompatibility of epoxy resins and cement-substrate materials, and environmental hazards [11][12][13][14][15][16].…”