Seismic performance study on the damage migration mechanism of precast grid shear walls: Influence of connection structure and steel reinforcement layout

To improve seismic performance through controlled damage migration and hierarchical energy dissipation, this study proposes a Precast Monolithic Grid Shear Wall (PMGSW) system incorporating coal gangue concrete (CGC) and bolted-welded dry connections. A three-level damage migration mechanism is established, progressing from initial cracking of the plain-concrete web, through crack bridging by the internal lattice reinforcement, to plastic energy dissipation in the boundary elements. Quasi-static tests on 1:2-scale specimens and validated nonlinear finite element analyses were conducted to clarify how connector configuration and internal lattice arrangement govern damage migration paths and flexure–shear responses. The results show that seismic performance is governed primarily by connector topology, while the effect of connector quantity depends strongly on whether the connectors are effectively engaged in the principal force-transfer path. Concentrating connectors at the bases of the boundary elements efficiently guides damage and plastic deformation toward the boundary regions, producing the highest displacement ductility of 2.98 and favorable damage localization and potential reparability. In contrast, additional connectors located outside the principal force-transfer path may disrupt force transmission and induce premature web shear cracking. A recommended lattice spacing range of s g = 300 ∼ 360 mm ( γ = 0.9 ∼ 1.1 ) was established, with s g , cr ≈ 330 mm representing the numerically identified critical grid size. An overall synergy index ( Γ ) was further established, from which the design criteria Γ ≥ 0.8 and d conn ≤ 1.2 b c were proposed.