An elastic-brittle damage constitutive model for modelling cracking of glulam

An elastic-brittle damage constitutive model for predicting cracking of Glulam was developed, which can be used to simulate the initiation and propagation of cracks in Glulam. Three main elastic-brittle failure modes, which take place in the planes of RL, TL and RT, respectively, were taken into account in the damage model. A failure criteria reflecting the combined effect of tension and shear was applied in the FE modelling, which also considered the duration of load (DOL) in the strength of Glulam. The status variables in the damage constitutive model were introduced to trace the extent of damage accumulated on the interfaces of the failure section and were only related to the components of tension and shear stresses in the cracking planes. In each cracking plane, the status variables describing the tension status in the normal direction are independent of each other, while those describing the shear status in the cracking plane are affected mutually. The model containing the damage model and failure criteria was incorporated into the commercial FE software ABAQUS by developing a user defined subroutine-UMAT. Then FE models to predict the bearing capacity and cracking in curved Glulam beam were developed. Experiments of curved Glulam beams cracking perpendicularly to grain were conducted to validate the FE modelling with the damage constitutive model. Experiments and numerical simulation results both showed that the cracking initiates from the part which is just a little below the neutral axis at the mid-span, and propagates toward both ends along the longitudinal direction. The bearing capacity of numerical simulation is also approximately correlate with the experimental results. Thus, the numerical modelling provides a validate technique to evaluate the design of curved Glulam beam.