Download or read book FRCM Composites for Strengthening Corrosion-damaged Structures written by Mohammed Elghazy and published by . This book was released on 2018 with total page 213 pages. Available in PDF, EPUB and Kindle. Book excerpt: Corrosion of steel reinforcement is one of the most destructive mechanisms for reinforced concrete (RC) structures. Corrosion not only impairs the structural integrity and the serviceability of the damaged structure, but it may also lead to unexpected and brittle failures. Despite the rigorous provisions of most codes of practice to avoid corrosion, evidences of corrosion damage are still being reported. Recently, fabric-reinforced cementitious matrix (FRCM) systems were proposed as an innovative strengthening/repair technique for RC structures to overcome the drawbacks associated with the use of the well-documented fiber-reinforced polymer (FRP) systems. While the use of FRCM composites to strengthen un-damaged RC members has proven its efficiency, very little is known about the viability of their use to retrofit RC members with various levels of corrosion damage. In addition, the post-repair performance and the long-term durability of the FRCM-strengthened corroded members, which most likely will be exposed to the same environmental conditions that have prevailed prior their repair, have not received attention in the literature. Moreover, most of our infrastructures such as bridges and parking garages are susceptible to corrosion damage while continuously being subjected to oscillatory loads that cause fatigue. To date, no information is available about the effect of combining fatigue loading with corrosion in FRCM-strengthened structures. In this work, the monotonic and fatigue flexural behaviors of corrosion-damaged RC beams strengthened with FRCM systems were investigated in addition to their long-term performance, i.e. after further exposure to corrosive environment following their strengthening. The work includes experimental and numerical investigations. The analytical predictions and theoretical formulations that are currently available in the design codes have been verified against the experimental results. The experimental program consisted of testing thirty (30) large-scale RC beams of 150×250×2800 mm. The beams were constructed and tested under four-point load configuration. An accelerated corrosion process was utilized to corrode the bottom steel reinforcement in the middle third of the test specimens. The test parameters included the level of corrosion damage (represented by 10, 20, and 30% mass loss in the tensile steel), the type of the strengthening system used (Polyparaphenylene benzobisoxazole (PBO-FRCM), C-FRCM, and FRP), the amount of FRCM composites (1, 2, 3, and 4 layers), the FRCM strengthening Scheme (end-anchored versus continuously wrapped layers), and the loading regime (monotonic and fatigue). The test results showed that the use of FRCM composites significantly enhanced the flexural behavior of the corroded beams. FRCM governed the failure mode of the strengthened beams rather than the level of corrosion damage of the steel bars. FRCM-strengthened beams showed an increase in their ultimate strengths that ranged between 7 and 65% of that of the virgin (neither corroded nor strengthened) beam based on the type, amount, and Scheme of the FRCM used. Exposing the repaired beams to post-repair corrosion resulted in 23% reduction in the steel mass loss. The U-wrapped scheme was more efficient than the end-anchoring scheme in delaying the delamination of the FRCM plies in the short-term repaired beams. It also mitigated the effect of the longitudinal corrosion cracks and consequently increased the post-repair strengthening effectiveness of FRCM systems. Fatigue tests showed that corrosion of steel bars dramatically decreased the fatigue life of the unstrengthened-beams. Strengthening with FRCM composites increased the fatigue life of the corrosion-damaged beams by 38 to 377% of that of the corroded-unstrengthened beams. However, FRCM strengthening did not restore the fatigue life of the virgin beams. In the numerical study carried out in this work, three-dimensional finite element (FE) models were developed to simulate the nonlinear behavior of the corroded beams strengthened with FRCM and FRP composites using the software package ATENA-3D. The results of the numerical analysis were in good agreement with those obtained experimentally in terms of failure modes, strains, load-carrying capacities, and deflections. The developed FE models were able to capture the non-linear behavior of the tested beams with good accuracy. A parametric study was then conducted to investigate the effect of concrete compressive strength and thickness of concrete cover on the strengthening effectiveness of the composite systems. It was observed that failure of RCM-strengthened beams was independent of the compressive strength of concrete or the thickness of the concrete cover and was governed only by fabric slippage within the matrix. Analytically, the design equations of ACI-549.4R-13 (ACI 2013) were assessed using the experimental data obtained from the tests. It was concluded that the theoretical formulations of CI-549.4R-13 can reasonably predict the ultimate strengths of the end-anchored strengthened beams but underestimated those of continuously-anchored beams. A scheme factor of 1.1 was then proposed to calculate the nominal strength of beams strengthened with continuously-wrapped shape of FRCM. The outcome of this work has been published (or submitted for publication) in five journal articles and five conferences, as detailed throughout the thesis.