Cloud Capacity Spectrum Method: Accounting for record-to-record variability in fragility analysis using nonlinear static procedures

This paper investigates a number of computational issues related to the use nonlinear static procedures in fragility analysis structures. Such approaches can be used complement dynamic procedures, reducing and modelling effort. Specifically, this study assesses performance Capacity Spectrum Method (CSM) with real (i.e. recorded) ground motions (as opposed code-based conventional spectra) explicitly account for record-to-record variability analysis. The focuses on single-degree-of-freedom systems, providing basis future multi-degree-of-freedom system applications. A case-study database 2160 inelastic oscillators is defined through parametric backbones different elastic periods, (yield) base shear coefficients, values ductility capacity, hardening ratios, residual strength hysteresis rules. These case studies are analysed using 100 motions. An efficient algorithm perform CSM spectra proposed, combined cloud-based approach (Cloud-CSM) derive relationships. Simple criteria solve issue multiple solutions two or more points backbone satisfying procedure) proposed tested. It demonstrated that point selection carried out based particularly intensity measure detected via optimal effectiveness Cloud-CSM discussed extensive comparisons time-history analyses, N2 method, simple method involving an as direct proxy displacement. provides errors lower than ±20% predicting median curves most cases outperforms other considered methodologies calculating dispersion.