Theoretical Analysis and Practical Prediction of Moment of Resistance of Timber Beams Strengthened By External CFRP Composites Using Universal Design Model

Abstract

The recently developed Universal design model is extended to Timber reinforced with CFRP in this paper. The required area of reinforcement CFRP in the Timber for any given Moment can be easily found using the model. Where the area of reinforcing CFRP is fixed, then the Moment of resistance can be estimated. The research reveals that for a fixed area of reinforcing CFRP an upper bound and lower bound moment of resistance matching the maximum moment that can be carried in compression by the weaker material (Timber) and the maximum moment that can be carried in tension by the stronger material (CFRP) respectively, when they act in composite. The paper reveals that the stronger material will assist the weaker material to the extent where there will be equilibrium of Moment of resistance, at which point the CFRP reinforced Timber section will fail. Existing Experimental results were confirmed. The only requirements in the method are the yield stresses of CFRP and Timber, and the section modulus of the cross section chosen. Though a rectangular section is discussed in this work, the model can be used for any cross section and shape with striking results.

Keywords: working stress; max bending moment; section moduli, Moment of resistance, timber, carbon fiber-reinforced polymer (CFRP).