External strengthening of reinforced concrete beam with opening by bamboo fiber reinforced composites

Abstract

This paper presents the structural behaviour of reinforced concrete (RC) beams with and without openings strengthened externally with bamboo fiber reinforced composite (BFRC) plates in shear and flexure, respectively. Mechanical properties include tensile and flexural strength of epoxy, polyester and vinyl-ester based BFRC plates with 0%, 10%, 20%, 30% and 40% fiber volume fractions were evaluated. A total of fourteen beams were cast to evaluate the structural behaviour of RC beams strengthened with BFRC plates. All the beams were tested to failure under four-point bending. The results presented were in terms of load–deflection behaviour, failure mode and crack pattern. A comparison was also made between the performance of epoxy, polyester and vinyl-ester based BFRC plates in shear strengthening of RC beams with openings. Results revealed that the presence of openings in the shear zone reduced the original beam capacity of the control beam to about 52–55%. Shear strengthening of RC beams with openings using epoxy based BFRC plates showed significant improvement in regaining the beam structural capacity to approximately 32–36% higher than the un-strengthened beams. Meanwhile, strengthening of RC beams in flexure with epoxy based BFRC plates managed to regain the beam original capacity up to 98% of the control beam. Bamboo fiber composite reinforced with epoxy, polyester and vinyl-ester resins of 40% fiber volume fraction managed to regain the beam original capacity up to 82%. It was found that BFRC plates could divert and mitigate the formation of cracks away from the strengthened region as well as improved the beam ductility.

Structural Retrofitting of Corroded Reinforced Concrete Beams Using Bamboo Fiber Laminate

“…Hafizah et al [25] research also showed that retrofitting beams with natural fibers increases beam deflection and stiffness, which is similar to the findings by Chin et al [22]. This was confirmed by this research also, as deflections for the corroded retrofitted beams increased by 22% compared to the un-strengthened corroded beam.…”

“…Bamboo as a reinforcing material is utilized in various forms such as mats, fibers, powder, and strips, with strips shown to have the better cohesive ability on structural members. Yet, most studies explore bamboo as a reinforcing material in retrofitting structural members, primarily as fibers [21,22] and few to none on strips. However, numerous studies covered bamboo fibers [31][32][33].…”

“…Most research on retrofitted beams dealt with various failure modes from flexural failure, concrete cover separation, and interfacial debonding [25,36]. Chin et al [22] research on the strengthening of RC beams in flexure with bamboo plates showed that retrofitting increased the beam's original capacity up to 98% of the control beam. Additionally, the research showed that the bamboo plates managed to alleviate and change the failure mode from brittle to more ductile behavior.…”

“…Bamboo is an adequate option amongst natural fiber as a composite in strengthening and retrofitting concrete elements. Its high tensile strength; cheaper cost compared to CFRP, wood, and steel; rapid growth; and mechanical and durability properties are some of the characteristics that are making this plant fiber gain increasing interest with researchers and engineers [19][20][21][22][23].…”

“…Using the four-point bending test, all the beams were tested to failure, and beams strengthened with BFCP were found to exhibit greater structural capacity strength compared to the un-strengthened beams. Chin et al [22] investigated the structural behavior of RC beams that were with and without openings strengthened externally with bamboo fiber-reinforced composite (BFRC) plates, both in shear and flexure. The investigations showed that the openings affected the original beam capacity negatively, and strengthening of RC beams with epoxy-based BFRC plates increased its capacity back to 98% of the control beam.…”