A bottom-up analysis of the seismic performance of prefabricated recycled concrete shear wall via concurrent macro-mesoscale numerical approach

Abstract

Uncertainty in the failure mechanism and damage evolution of recycled aggregate concrete (RAC) due to complex components largely restricts the practical application of RAC in load-bearing members. In this study, a feasible concurrent macro-meso numerical approach is proposed to investigate the seismic performance of prefabricated recycled concrete shear wall (PRCSW), with an emphasis on revealing the failure mechanisms at both the material and structural scales. Specifically, RAC is regarded as a multiphase heterogeneous material that is represented by an elaborative mesoscale random aggregate model consisting of six phases. The collective mechanical responses of RAC are reasonably captured under various replacement rates of recycled aggregate (Rra = 0, 30%, 50%, 70%, and 100%) and volume fractions of old mortar (Vom = 12%, 16%, 20%, and 24%). In addition to this, a practical concurrent macro-mesoscale model of PRCSW is established, in which the mesoscale model of RAC is exclusively exploited in the critical vulnerable regions (e.g., concealed beam, column, and bottom of wall limb), while the macroscale model is utilized for the remaining regions, striking a balance between computational efficiency and accuracy. To facilitate the numerical implementation, a highly effective approach using Linear Multi-Point Constraint (LMPC) is adopted to establish connections between models operating at varying scales, thus allowing for the simulation in parallel. Upon such a bottom-up numerical analysis, the results show that due to the significantly weakened properties of old mortar and the inclusion of associated interfacial transition zones (ITZs), the damage development and mechanical performance of RAC are quite different from that of ordinary concrete, manifesting as the amplified accumulation of damage around aggregates and severe fractures of recycled aggregates. Although the addition of RAC (Rra increases from 0 to 100%) is found to slightly weaken the horizontal seismic bearing capacity of PRCSW (decreased by 8.57%), its structural deformation capacity, however, is obviously compensated (increased by 34.42%), resulting in a marginal variation of energy dissipation capacity. The findings facilitate the utilization of substantial RAC in load-bearing members with higher confidence.