From Service Level to Maximum Considered Earthquake: Evaluating the Seismic Response of a Ten-Story Cold-Formed Steel-Framed Building

A high-fidelity nonlinear numerical model was developed in OpenSeesPy for the CFS10, a full-scale ten-story cold-formed steel (CFS) framed building tested at the University of California San Diego's Large High-Performance Outdoor Shake Table (LHPOST6), in June 2025, under 18 multi-directional ground motions of increasing intensity. The model captures material and geometric nonlinearities across structural and nonstructural components. Buckling of framing members is taken into consideration using material definitions that account for the interaction of yielding with local and distortional buckling. Shear wall sheathing hysteretic behavior, including pinching effects and strength and stiffness degradation, is captured through models calibrated against component-level data from the cold-formed steel-framed shear wall test database. Tie-rod anchorage systems, hold-downs, and the lateral resistance of nonstructural finishes are also accounted for. The model is validated against the CFS10 experimental measurements, with close agreement observed across global and local response metrics. Using the validated model, the ten-story building response is evaluated under the 1994 Northridge Canoga Park–Topanga Can ground motion record scaled to Service Level Earthquake (SLE), Design Earthquake (DE), and Risk-Targeted Maximum Considered Earthquake (MCER) intensities. Interstory drift ratios and story shear forces are compared across the three hazard levels, illustrating the progression of nonlinear behavior with increasing earthquake intensity in taller CFS-framed buildings.