Abstract | Seismic fragility curves are an essential tool for any risk assessment endeavour. While there is a wealth of studies that have provided high quality fragilities for many different types of structures, these curves are typically presented in terms of a single intensity measure (IM). To keep using such valuable data, an analyst is either forced to adopt the same (potentially suboptimal) IM, or completely discard them and restart with a new one. Instead, we propose a simple method for transforming a fragility curve to any IM of choice by using an equivalent single-degree-of-freedom model and its incremental dynamic analysis results to disaggregate the fragility to its constituent record-level results. Validation results from two complex 2D building hint that there is promise to this approach, offering nearly-error-free transformations of global-response fragilities at the cost of a few response history analyses of a nonlinear oscillator.