Simplified Mechanical Analysis Method for Assembled Composite Shear Walls with C-Shaped Steel Frames

To reduce the modeling effort and computational cost of assembled composite shear walls with C-shaped steel frames in global structural analysis, this study proposes an engineering-oriented simplified mechanical analysis method. Three representative specimens—a C-shaped steel-frame composite shear wall (CSCSW), a rectangular steel-frame composite shear wall (RSCSW), and a T-shaped, C-shaped steel-frame composite shear wall with a vertical connection (VTCSWC)—are decomposed into functional modules according to their load-transfer mechanisms. Simplified models comprising axial springs, diagonal braces, and a modified three-vertical-line-element model are established. Degrading bilinear Clough and trilinear Takeda models are adopted as the restoring-force relationships, and the governing parameters are determined through mechanical equilibrium analyses. The three simplified wall models are implemented in OpenSees to obtain hysteresis curves, skeleton curves, and stiffness-degradation responses. Comparisons with quasi-static test results show that the errors in peak load and secant stiffness are both within 10%, while the models reproduce the stiffness degradation and pinching characteristics of the specimens. Relative to refined three-dimensional solid finite element models, the proposed approach substantially reduces computational cost without compromising engineering accuracy, providing an efficient tool for structural design and seismic performance assessment of assembled C-shaped steel-framed composite shear-wall systems.