Seismic Performance of Multistorey Steel Buildings with Different and Hybrid Bracing Configurations: A Critical Review

Bracing is the most common means of stiffening multistorey steel buildings against earthquakes, yet published comparisons of brace geometry are hard to combine because each rests on its own building, design basis, analysis procedure and response measure. This paper critically reviews, in narrative form, twenty-nine studies of braced steel frames and of incremental dynamic analysis (IDA). The studies are grouped into comparisons of conventional geometries, eccentric and strongback systems, hybrid systems, and IDA-based work, and are compared in terms of building height, analysis level and the response quantities each reports. The literature agrees that bracing reduces drift and displacement relative to an unbraced frame. It does not agree on which geometry is best: the favoured arrangement changes with building height, analysis procedure, response measure and the importance given to cost or collapse. Hybrid bracing has been developed mainly by combining components or devices, such as buckling-restrained braces with self-centring or friction elements, whereas combinations of brace geometries within one building have received little attention. Where IDA is used, each building usually carries a single brace layout. Four research gaps are identified, and the design of a controlled study that would address them is outlined: one building, one design basis, one ground-motion set, IDA, and several response measures with their uncertainty reported.