Research on thermo-mechanical coupled damage of high-temperature concrete based on close-packed model

This study employs ABAQUS numerical simulations to compare a model incorporating aggregates with a homogeneous model without aggregates. This comparison reveals the mechanical properties and micro-damage characteristics of concrete after exposure to high temperatures. The study systematically elucidates the intrinsic degradation mechanisms of concrete under thermo-mechanical coupling, spanning from macro to micro scales. It also highlights the advantages of the proposed close-packed model. The findings indicate that both peak stress and elastic modulus exhibit nonlinear reductions as temperature increases in high-temperature concrete. Stress-strain variation patterns demonstrate similarities across both models. The close-packed model effectively represents the mesoscale damage characteristics of high-temperature concrete. High temperatures significantly lower the stress threshold for damage initiation, and the damage evolution gradually slows down. The damage transitions from localized expansion at the aggregate-matrix interface to a globally diffuse expansion. Furthermore, the close-packed model effectively captures the settlement and packing characteristics of aggregates during the actual pouring process, addressing homogeneous models and random aggregate models that overlook physical processes.