A promising use for high performance composite materials is to reinforce timber beams. The present paper studies the use of carbon and glass fibres to reinforce sawn timber sections. Consideration is given to strength phenomena of commercial timber alone and in reinforced sections in bending and shear. Anchorage length considerations for composite strips applied to the underside of simple beams are discussed. Experimental results are presented for three geometries of reinforcement using matched samples of 25 pairs of beams, reinforced and not. Results establish that the wood itself in the composite section shows strength increase, and that the increase in moment resistance of the reinforced beams is far greater than that predicted by simple models.Key words: composite material, timber, reinforcement, bending, shear.

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Combined bending and axial loading is often encountered in lumber and timber members. Existing design methods are based on studies carried out many years ago, and are no longer appropriate because they do not recognize that wood with defects behaves in compression as a nonlinear ductile material and in tension as an elastic brittle material subject to size effects. This paper summarizes the findings of a comprehensive investigation into the behaviour of lumber subjected to eccentric axial loading, which was carried out at two Canadian universities. The study included analytical modelling and an extensive experimental program using full-size lumber.The results of the investigation have been used in this paper to propose improved design methods, using design charts and approximate formulae for in-plane behaviour. The discussion is extended to general loading cases and biaxial behaviour. lnput information required for the design process is also discussed.Les tltments en bois sollicitts a la fois par un effort normal et un moment de flexion sont trks frtquents. Les rnethodes de calcul actuelles sont fondtes sur des thtories ttablies il y a de nombreuses anntes et ne sont plus approprites car elles ne tiennent pas compte que les dtfauts du bois en font un mattriau ductile non lintaire en compression et un mattriau fragile sujet aux effets des dimensions en traction.Cet article rtsume les rtsultats de recherches, poursuivies par deux universitts canadiennes, sur le comportement d'iltments en bois sollicitts par une charge norrnale excentrte. L'ttude comprend une modtlisation mathtmatique et une analyse exptrimentale utilisant des tchantillons de bois grandeur nature.Les rtsultats de ces recherches ont permis d'ttablir des rntthodes de calcul utilisant des abaques et des fonnules approprites 2 un comportement bi-dimensionnel. La discussion considbre Cgalement les cas gentraux de mise en charge. Les donntes ntcessaires aux calculs sont tgalement traittes.[Traduit par la revue]Can. J. Civ. Eng. 12. 731-744 (1985)