Ahmed El Refai

Durability and Fatigue of Basalt Fiber-Reinforced Polymer Bars Gripped with Steel Wedge Anchors

This paper presents the test results of a durability study on a novel basalt fiber-reinforced polymer (BFRP) bar-anchor system. The BFRP bars were exposed to saline and alkaline solutions for 10 weeks before being anchored and tested under static and fatigue loading. Unconditioned basalt, glass, and carbon specimens were also tested and served as controls. Regardless of the fiber material, all the bar-anchor systems withstood their ultimate tensile loading with no sign of slippage or premature failure in the anchor zones. Conditioning of the BFRP bars in saline and alkaline solutions resulted in 7 and 9% decreases, respectively, in the systems’ tensile capacity. A decrease of 11% in the modulus of the alkali-conditioned BFRP specimens was also observed. The fatigue test results showed that the fatigue life of the bar-anchor system was primarily affected by the applied stress range. In addition, continuous immersion of the BFRP bar in the alkaline solution increased its tendency to fracture prematurely in the anchor zone. The fatigue limit of the BFRP bar-anchor system was determined to be 4% of its ultimate capacity, compared with 3 and 10% for the glass and carbon systems, respectively.

Bond Performance of Basalt Fiber-Reinforced Polymer Bars to Concrete

This paper presents the test results of a study on the bond behavior of basalt fiber-reinforced polymer (BFRP) bars to concrete. Thirty six concrete cylinders reinforced with BFRP bars and twelve cylinders reinforced with glass fiber-reinforced polymer (GFRP) bars were tested in direct pullout conditions. Test parameters included the FRP material (basalt and glass), the bar diameter, and the bar embedment length in concrete. Bond-slip curves of BFRP and GFRP bars revealed similar trends. BFRP bars developed average bond strength 75% of that of GFRP bars. All BFRP specimens failed in a pullout mode of failure along the interfacial surface between the outer layer of the bar and the subsequent core layers. The influence of various parameters on the overall bond performance of BFRP bars is analyzed and discussed. The well-known BPE and modified-BPE analytical models were calibrated to describe the bond-slip relationships of the bars. Test results demonstrate the promise of using the BFRP bars as an alternative to the GFRP bars in reinforcing concrete elements.

Numerical Simulation and Experimental Testing of Concrete Beams Strengthened in Shear with Fabric-Reinforced Cementitious Matrix

AbstractThis paper presents results of finite element (FE) modeling and experimental testing of reinforced concrete beams strengthened in shear with fabric-reinforced cementitious matrix (FRCM). The studied parameters included the number of FRCM layers (one and two layers), matrix type (mortar and epoxy), and amount of internal stirrups (no stirrups and stirrups with spacings of 0.6d and 0.3d, where d is the depth of the tensile steel). Test results showed that the shear-strength gain after strengthening was in the range of 51–145%. The shear-strength gain decreased with an increase in the amount of internal stirrups. Doubling the number of FRCM layers resulted in a nonproportional increase in the shear strength. The use of epoxy adhesive rather than a cementitious mortar as a matrix insignificantly increased the shear-strength gain. The effect of increasing the amount of FRCM or varying the matrix type on the shear strength was less pronounced for the specimens with internal stirrups. The FE models devel...

Concrete Contribution to Shear Strength of Beams Reinforced with Basalt Fiber-Reinforced Bars

AbstractThis paper reports on the shear behavior of concrete beams reinforced with basalt fiber-reinforced polymer (BFRP) bars. In this study, 10 reinforced concrete beams with no transverse reinforcement, including 2 beams reinforced with longitudinal steel bars, were constructed and tested until failure. The test variables were the longitudinal reinforcement ratio and the span-to-depth ratio of the beams. The test results were compared with predictions of different available codes and design guidelines. Shear design equations of the CAN/CSA-806-12 code and the JSCE-97 guidelines provided accurate predictions. However, the predictions of CAN/CSA-806-12 were not conservative in some cases, whereas those of the ACI-440.1R-15 and the CAN/CSA-S6-10 were conservative. The test results were combined with the experimental results of a large database, including 75 beams and one-way slabs reinforced with carbon, glass, aramid, and BFRP bars. The behavior of beams reinforced with BFRP bars was quite similar to tha...

Performance of FRCM-Strengthened RC Beams Subject to Fatigue

Fabric reinforced cementitious matrix (FRCM) is a relatively new material system recently developed for the repair, retrofit, and rehabilitation of reinforced concrete (RC) and masonry structures. Concrete structures such as bridges experience high traffic volumes and varying vehicle axle weights causing repeated cyclic loading throughout their lifetime. Cyclic loading may cause damage to the structure, a phenomenon known as fatigue. Due to the novelty of FRCM technology, there is a lack of research regarding the long-term performance of FRCM systems for RC strengthening. This study aims to investigate experimentally the parameters that most influence the flexural fatigue performance of Polyparaphenylene benzobisoxazole (PBO) FRCM strengthened RC beams. For members subject to cyclic loading, a stress ratio vs. the number of cycles (S-N) curve is developed with the objective of defining the endurance limit of the strengthened beams. Failure mode and fatigue life of the beams during cyclic loading are investigated and discussed.

Structural Health Monitoring and Assessment: Sensors and Analysis

Department of Civil and Environmental Engineering, Incheon National University, Incheon 22012, Republic of Korea Incheon Disaster Prevention Research Center, Incheon National University, Incheon 22012, Republic of Korea Department of Public Works and Civil Engineering, Mansoura University, Mansoura 35516, Egypt Department of Structural Engineering, Mansoura University, Mansoura 35516, Egypt Department of Civil and Water Engineering, Laval University, Québec, QC, Canada G1V 0A6