Wood^ST: A Temperature-Dependent Plastic-Damage Constitutive Model Used for Numerical Simulation of Wood-Based Materials and Connections

Abstract

The thermomechanical behavior of members and connections plays a crucial role in the fire safety of timber construction. In this study, a unique constitutive model, WoodST, combining a number of mechanics-based submodels was developed for numerical simulation of wood-based materials and connections under forces and fire. The extended Yamada–Sun strength criteria were utilized to judge the brittle failure or ductile yielding in different directions and stress conditions. A strain-based damage evolution was developed to describe the postpeak softening of brittle failure in tension or shear. A plastic flow and a hardening law were established based on the strength criteria to depict the plastic stress-strain relationship of ductile yielding in compression. A strain-based hardening evolution was developed to implement a second hardening (densification) under compression perpendicular to grain. A multilinear reduction model was adopted to represent the influence of fire on the mechanical properties of wood-based materials. The developed model was used to model the structural response of a laminated veneer lumber (LVL) beam and a glulam bolted connection under force and fire. It is demonstrated that the proposed constitutive model was capable of simulating the thermomechanical response of LVL beam and glulam connection under force and fire within 10% difference between modeling and testing results.