REFINED ANALYTICAL COLLAPSE CAPACITY SPECTRA

Recently, two of the authors have introduced the collapse capacity spectrummethodology, which allows the assessment of the collapse capacity of highly inelastic P-deltasensitive regular frame structures without performing non-linear time-history analyses. The mainingredient of this method is the collapse capacity spectrum, which represents the seismic collapsecapacity of an inelastic non-deteriorating single-degree-of-freedom system vulnerable to the Pdeltaeffect as a function of its initial period, negative post-yield stiffness ratio, viscous dampingcoefficient, and the shape of the hysteretic loop. In the present study, multiple linear regressionanalyses are applied to provide enhanced analytical expressions of these spectra. The record-torecorduncertainty of the collapse capacity is captured through median, 16th and 84th percentilespectra. For several test systems analytical collapse fragility functions based on these spectra areset in contrast with the corresponding sorted individual collapse capacities. These examples provethe superiority of the proposed analytical expressions compared to its original formulation.