Strengthening of wooden members using glass and abaca fiber reinforced composites | |
| Author | Opiniano, Napoleon M., Jr. |
| Call Number | AIT Thesis no.ST-02-7 |
| Subject(s) | Fibrous composites Wooden beams |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering. |
| Publisher | Asian Institute of Technology |
| Abstract | There is a need to develop cost-effective methods for strengthening and rehabilitation of existing wooden structures, considering the depleting forest reserves observed in most developing countries. This study presents an experimental investigation involving external bonding of thin synthetic and natural fiber reinforced polymer (FRP) composite sheets on the tension zones of full-scale and small-scale wooden beams using epoxy resins. The wood species selected for this study is Teng, a hardwood commonly used in Thailand. Full-scale beams are reinforced with a thin layer (1 mm) of unidirectional glass FRP (GFRP), and their performance is compared to plain wood controls. For small-scale beams, abaca FRP (AFRP) as reinforcement is investigated, using a 4. 7% fiber volume fraction, by varying number of abaca mesh layers bonded. The performance of AFRP-reinforced beams is compared with plain wood controls and GFRP-reinforced specimens having a 45% fiber volume fraction. Abaca fiber mesh reinforcement is obtained from the Philippines. Flexural tests under third-point loading are conducted, and mechanical properties relating to strength, stiffness and toughness are evaluated, serving as indices of performance. Physical properties of abaca fibers and tensile strength of AFRP composite coupons are also determined. Test results showed that GFRP reinforcement provided significant improvements in the mechanical behavior of full-scale beams, with average increases of 95% in modulus of rupture, 47% in modulus of elasticity and 246% in toughness. Assuming minimum strength gains, one layer of GFRP can produce at least 45% cost savings in using a larger all-wood section to achieve similar enhancements. AFRP-reinforced small-scale beams showed improvements up to 36% in modulus of ruptu.re, 13% in modulus of elasticity and 142% in toughness of control beams, comparable to using GFRP-reinforcement, which produced increases up to 23% in modulus of rupture, 4% in modulus of elasticity and 144% in toughness. Minimal abaca fiber debonding occurred at beam failure, indicative of adequate bond strength provided. But improvements are achieved at the expense of more abaca mesh layers bonded compared to glass, requiring more consumption of the high-cost adhesive making AFRP reinforcement more expensive. This is due to the lower tensile strength of abaca fibers, the bi-directional mesh configuration of abaca reinforcement, which reduces reinforcement efficiency along the longitudinal direction by half, and the much lower abaca fiber volume fraction used. But comparison under the same fiber volume fraction of 45%, with abaca fibers being much less expensive and lighter than glass fibers, revealed that AFRP composites cost 34% less than GFRP. This can reduce the number of AFRP layers required to achieve comparable efficiency with GFRP composites. Thus, abaca fibers offer a good potential to replace glass fibers as polymer reinforcement. |
| Year | 2002 |
| Type | Thesis |
| School | School of Engineering and Technology (SET) |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Structural Engineering (STE) /Former Name = Structural Engineering and Construction (ST) |
| Chairperson(s) | Pichai Nimityongskul |
| Examination Committee(s) | Barry, William J.;Kim, |
| Scholarship Donor(s) | Royal Thai Government (RTG) |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2002 |