Semester

Fall

Date of Graduation

2002

Document Type

Dissertation

Degree Type

PhD

College

Statler College of Engineering and Mineral Resources

Department

Civil and Environmental Engineering

Committee Chair

Julio Davalos.

Abstract

For applications in civil infrastructure rehabilitation and new construction, wood is being reinforced with externally bonded laminates and fabrics of fiber-reinforced polymer (FRP) composites. The potential benefits of external reinforcement with bonded FRP composites have been demonstrated through several studies, and the field implementation of this technology has been successfully proven in numerous projects. However, there is a concern with the long-term performance of the interface bond, since an inadequate bond strength and integrity can render the reinforcement ineffective and lead to premature failure of the structure. The performance of FRP-wood bonded interfaces under static and environmental loads have been explored extensively at WVU, and as an extension of this effort, present study will examine, for the first time, the fatigue behavior of FRP-wood bonded interfaces.;The objective of this study is to develop a combined analytical and experimental fracture mechanics method to evaluate the fatigue behavior of phenolic FRP-red maple wood bonded interfaces under constant cyclic load conditions. The possible effect of loading variables (load ratio, waveform and frequency) on crack propagation rate is studied. The fatigue threshold is determined at the conclusion of this project, and the possible load ratio effect on fatigue threshold is investigated. The study of constant amplitude fatigue on bonded interfaces provides valuable insights into the mechanical processes by which fatigue failure can occur for actual structures or member under varying amplitude cyclic loading.;Fatigue failure of materials and bonded interfaces is a very complex topic, and yet a quite important issue in engineering practices. The application of linear elastic fracture mechanics concepts has resulted in some reasonable and useful explanations of fatigue failure. By modifying the original Paris Law equation, we can efficiently evaluate the fatigue behavior of FRP-wood interface bond-line, and this method can further be used for other similar studies of interface fracture of dissimilar materials. Thus, the findings of this study can eventually lead to the development of guidelines for hybrid material bonded interface design under constant cyclic loading conditions.

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