Flexural analysis and design of timber strengthened with high-strength composites

A non-linear model that provides an accurate prediction of clear wood and timber in bending is presented in this dissertation. The model is then applied to FRP strengthened timber beam. Comparison of the results obtained using the proposed model and the experimental results indicate that the behavior of strengthened wooden beams can be predicted with reasonable accuracy. A step by step design procedure for FRP strengthened timber beams is presented to effectively obtain the area of FRP needed to satisfy the increased timber beam strength requirements.; The non-linear stress-strain model for unstrengthened beams is an elasto-plastic behavior in compression, and linear elastic in tension. The strength model uses the relationship between flexural properties and modulus of elasticity to define the equivalent elastic compressive strength used in model. The model can be used in clear wood, lumber and timber strength analysis.; Using the brittle fracture theory, a relationship between lumber modulus of rupture and bending strength is established through stress distribution parameter. The stress distribution parameter can be estimated through in-grade test results of modulus of rupture and axial compression strength. Once stress distribution parameter is found, the axial tension stress of lumber can be predicted from modulus of rupture.; The non-linear strength model for unstrengthened beams is modified for using in strengthened timber beam. A linear descending stress-strain curve is assumed for post-peak tensile stress region of timber for strengthened timber beams. The analytical results match very well with strengthened timber beam experimental investigation.