Wood Glass-Fiber Reinforced Polyester (GFRP) Hybrid Cross-Section Used to Improve the Structural Behavior of Timber Beams

Abstract

Composite systems used for increasing the load bearing capacity of timber structural elements are of special interest for engineers, basically because of their beneficial weight/strength ratio. By creating a hybrid cross section composed of wood and interposed GFRP lamellae, the improvement of wood limited elastic properties may be achieved, considering the compatibility between composite materials matrix, thermosetting unsaturated polyester resin, and wood. The main objective of the paper is to carry out an experimental study on the technical solution represented by associating these two materials with similar structures, both pertaining to the class of composites reinforced with long fibres and bonded, for the case of wood by lignin and hemicelluloses and for the case of GFRP by unsaturated polyester resin. The experimental program consists in performing the bending test of timber beam type structural elements, considering two types of cross-sections, the first being composed by joining three timber boards of 25x100x1900 mm by aid of screws and the second, with wood/GFRP hybrid cross-section, having the same number of timber boards as specified above joined together by two 3...5x100x1900 mm GFRP interposed lamellae. Determination of some physical and mechanical properties, in the laboratories of Faculty of Civil Engineering and Building Services, Iasi, Romania and the obtained results are comparatively presented for the two types of tested beams, the final step of the paper consisting in optimizing the technology involved for execution of the hybrid structural element.