Structural evaluation and design procedure for wood beams repaired and retrofitted with FRP laminates and honeycomb sandwich panels

• Published in: Composites. Part B, Engineering Vol. 87; pp. 196 - 213
• Main Author: Mosallam, Ayman S.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15-02-2016
• Subjects: A. Honeycomb; A. Polymer-matrix composites (PMCs); B. Strength; B. Stress concentration; Beams (structural); D. Mechanical testing; Design analysis; Fiber reinforced plastics; Honeycomb; Laminates; Retrofitting; Sandwich construction; Wood; A. Polymer-matrix composites (PMCs); B. Strength; A. Honeycomb; D. Mechanical testing; B. Stress concentration
• ISSN: 1359-8368; 1879-1069
• DOI: 10.1016/j.compositesb.2015.09.053

As compared to other structural applications of polymeric composites, limited information is available on structural behavior of wood members strengthened with polymer composites. The focus of this paper is to evaluate the structural performance and practical use of wooden beams repaired and retrofitted with fiber-reinforced-polymeric (FRP) composites. The paper presents a summary results of an experimental study on the behavior of both Douglas Fir and Glulam wood beams repaired and retrofitted with different composite strengthening systems. In addition, the paper presents a simplified design procedure to predict the capacity of timber beams strengthened with FRP composites. Two types of composites; wet layup laminates and sandwich panels, and two lamination schedules; unidirectional and bidirectional, and two lamination geometries; U-laminate and flat laminates were evaluated. For “flexure/shear” wood beams repaired and retrofitted with bidirectional, carbon/epoxy U-shaped wet layup laminates, a total of eight Douglas Fir (Dug Fir) Larch # 1 wood beams were tested to failure. For “flexure-only” wood beams retrofitted with flat unidirectional laminates, both wet layup and precured sandwich honeycomb composites were evaluated. Experimental results indicated that the use of composites as external repair and rehabilitation elements resulted in an appreciable increase of both strength and stiffness. A practical case study is also presented that provides a step-by-step procedure for analyzing and designing a polymeric composite system for repair of partially damaged wood girders by fire.