Out-of-plane flexural behaviors of curved steel-plate composite walls with small curvature radius-to-section thickness ratio

Curved steel-plate composite (SC) walls have been increasingly adopted in nuclear engineering owing to their superior seismic performance and suitability for modular construction. In this study, the out-of-plane flexural behavior of curved SC walls under cyclic lateral loading was experimentally investigated through tests on five curved specimens and two flat specimens, considering the influence of the curvature radius-to-wall thickness ratio (R/T) and the connector spacing-to-steel plate thickness ratio (b/t). The experimental results demonstrate that the curvature effects become significant when R/T < 20. Compared with flat SC walls, curved SC walls exhibit an increase of approximately 4%-8% in out-of-plane flexural capacity. Owing to geometric asymmetry, curved SC walls also exhibit different flexural capacities under opposite loading directions of up to 7%-10%. A finite element model is developed and calibrated against the test results, and the subsequent parametric analyses indicate a coupled influence of R/T and b/t: SC walls with smaller R/T are less sensitive to variations in b/t. Based on theoretical derivations, a calculation method is proposed for predicting the out-of-plane flexural capacity of curved SC walls, explicitly accounting for both curvature effects and steel plate buckling.