N-M interaction curves for timber members’ cross-section under ambient and high temperature

Resumo

Widely used for structural calculation, axial force (N) - bending moment (M) interaction curves are suitable instruments for evaluating the structural elements cross-section capacity, relating the ultimate values of bending moment and axial force. Also known as resistance curves in ambient temperature and fire situation, the N-M curves become strongly dependent on the temperature field because of the physical and mechanical changes that occur in the material under elevated temperatures. Therefore, the present study aims to obtain the interaction curves of timber structural elements cross-section of commonly used members in civil construction, subjected to the action of thermal conditions (ambient and high temperatures), using a generalized numerical strategy based on the strain compatibility method (SCM) and Newton-Raphson method coupling. The adopted strategy is validated through the construction of N-M curves for timber cross-sections, subject to ambient temperature and different fire configurations and temperature distribution. The results obtained are compared with answers available in the literature.