Domain decomposition method for simulating the cracking of cross-laminated timber structures

Technological advances in cross-laminated timber (CLT) have promoted its use in medium- and high-rise buildings due to its excellent strength-to-weight ratio, good seismic performance, and insulating capacity. However, predicting the response of CLT structures remains a challenge, as multiple failure modes under load, both in-plane and out-of-plane, interact. In particular, rolling shear failure is a critical issue in out-of-plane loads, affecting transverse layers and propagating both inter and intralaminarly. Under in-plane loads, the interaction between buckling and interlaminar cracking compromises the load bearing capacity of CLT panels. In both cases, the nature of these damage mechanisms and their interaction result in significant structural performance losses, limiting the optimal use of the CLT. Furthermore, the multiscale and anisotropic nature of wood, combined with the high computational cost of detailed models, needs the development of efficient strategies to simulate the non-linear response of CLT structures, particularly strategies adapted to parallel computing. This work develops a parallel computing strategy based on a mixed-domain decomposition method, the LaTIn micro-macro method, whose advantages have been previously demonstrated for studying the interaction between delamination, buckling, and contact in fiber-reinforced composites. By combining this strategy with cohesive zone models, the objective is to capture the non-linear response of CLT as failure under bending and compression. To optimize the strategy, algorithmic improvements are introduced to reduce the number of iterations and to more accurately represent the initiation and propagation of cracks in orthotropic materials. In addition, a detailed analysis of the physics of the problem is conducted, together with a review of experimental tests reported in the literature, to define an efficient domain partition approach. To validate the strategy, a four-point bending test is simulated on a three-layer panel, reproducing the occurrence of rolling shear failure and its interaction with other damage mechanisms, showing good correlation with experimental results reported in the literature. In the case of in-plane loads, a reduction in critical load is observed because of the interlaminar adhesive, and critical areas prone to delamination are identified in CLT panels. The proposed approach provides an effective tool for designing more reliable CLT structures, with the possibility to extend to five- and seven-layer configurations, as well as to concrete hybrid systems.