Influence of mixing tropical timber species and material heterogeneities on the long-term stability of slender glulam beam columns

Abstract

ABSTRACT Slender glulam beams are high value products that may be used differently concerning large span structures. They can be manufactured in developing countries without significant industrial resources by using two tropical timber species, while preserving emblematic species and promoting lesser known ones. The current Eurocode 5 design rules, based on the effective length method, are not adapted for designing such products, subjected to axial compression. An approach, based on a work-energy method, is investigated in this work. The goal of the paper is to provide a refined modeling of the long-term buckling strength of mixed and slender tropical glulam beam column, based on the finite element method. The variability of the rheological properties of the materials is considered, as well as the geometrical imperfection of the product, characterized by initial deflection. Variations of the glulam composition are also considered. Monte-Carlo simulations of the beam behavior over time are performed. Results provide for each glulam composition a set of analytic and decreasing evolution of the long-term buckling strength with time. The relative gap between the initial and final critical load can reach up to 18%. The possibility of optimizing the parameters that drive the long-term stability of beams is discussed. Moreover, the study may unlock a new standard design approach for the designers and engineers, aiming at guaranteeing the long-term safety of the slender and mixed glulam products.