Behaviour factor evaluation of CFS shear walls with gypsum board sheathing according to FEMA P695 for Eurocodes

Abstract

Earthquake standards around the globe are progressing towards adopting an advanced performance based seismic design approach, providing the guidelines for the newer innovative seismic force resisting systems and codifying the seismic performance of already in use structural systems. Gypsum board panels are among one of the many types of panels currently widely used in the Light Weight Steel (LWS) constructions made of the Cold Formed Steel (CFS) frames primarily for sheathing the studs to form an envelope of the building. Contrarily, there choice as the sheathing panel for shear walls resisting the seismic loads in LWS construction is rather limited due the lack of guidelines on their seismic performance in European standards. The work presented here in attempts to bridge this gap by evaluating a suitable value of their behaviour factor, which is one of the significant measures for quantifying the seismic response, through a numerical study performed following the procedures of FEMA P695. A set of fourteen archetypes, which represent a range of design parameters and the building configurations are designed following the capacity design approach and their response is idealized by the nonlinear models. The performance of archetype models is evaluated systematically through the static pushover and the incremental dynamic analysis under a suite of forty-four normalized and scaled earthquake records, representing the probable seismic hazard to the buildings. Finally, by calculating the collapse probability while also considering the uncertainties from various sources, the suitability of trial value of behaviour factor used in the design phase of archetypes is evaluated. Based on the results, it is concluded that a behaviour factor (q) of 2.0 for the CFS shear walls with gypsum board sheathing is appropriate.