Selecting, scaling, and orienting three components of ground motions for intensity‐based assessments at far‐field sites
N. Simon Kwong, Anil K. Chopra
Abstract
This article develops a methodology for selecting, scaling, and orienting three orthogonal components of ground motion (GM) when conducting intensity‐based assessments of structures. Target spectra for selecting multicomponent GMs are critically examined and strategies for selecting hazard‐consistent GMs are investigated. The Conditional Mean Spectrum–Uniform Hazard Spectrum (CMS‐UHS) Composite Spectrum is proposed as an alternative to several Conditional Mean Spectra for selecting multicomponent GMs when conducting intensity‐based assessments of complex three‐dimensional (3D) structures. To ensure hazard consistency, multicomponent GMs should be selected using (a) the target spectrum for the vertical component of GM, (b) a wide range of vibration periods, and (c) scale factors that are constrained. With constrained scale factors, all three components of a GM can be reasonably scaled either by the same scale factor or by different scale factors.