Parametric cost-performance-based design of triple friction pendulum (TFP) isolators

This study presents a parametric framework developed for the cost performance based design of triple friction pendulum (TFP) isolators. The framework systematically generates isolator configurations by varying the friction coefficient, curvature radius, and geometric sliding distances within predefined ranges, enabling an efficient evaluation of cost performance relationships. The stiffest configuration, representing the minimum required displacement capacity, was selected as a reference, and both Equivalent Lateral Force (ELF) and Nonlinear Response History Analyses (NRHA) were performed on a four-story reinforced concrete building. Spectrum compatible ground motion records were selected using a least-squares-based matching procedure, and cost estimation was conducted based on the volumes of the inner and outer concave plates in accordance with EN 1337-2. Configurations satisfying the base displacement demand of the reference isolator were ranked by cost and evaluated in NRHA for inter-story drift, floor acceleration, and base displacement responses. Results indicate that parameters such as curvature radius ratio, effective damping, and volumetric proportions significantly affect cost. The findings highlight that similar design targets, such as base displacement capacity, effective isolation system period, and base shear ratio, can be achieved at considerably different costs, with variations up to 35% even within a ± 10% tolerance range. The proposed framework, implemented through MATLAB scripting and ETABS modeling, integrates parametric modeling, seismic performance assessment, and cost evaluation to identify the most efficient TFP isolator configurations that satisfy both seismic and economic design criteria.