Seismic Performance Factors for Cross-Laminated Timber Shear Wall Systems in the United States

Abstract

Seismic force resisting systems based on cross-laminated timber (CLT) shear walls have garnered considerable attention for in mid-rise construction around the world. The purpose of this study was to determine seismic performance factors for CLT shear wall systems in platform type construction. These factors, namely, the response modification factors, R, overstrength factor, Ωo and deflection amplification factor, Cd, have been developed in this study for CLT walls and proposed for inclusion in ASCE 7. The study follows the FEMA P695 methodology that incorporates testing, evaluating a design methodology, defining the design space representative of typical construction, and comprehensive performance evaluation. The testing phase of the project consisted of connector testing and CLT shear wall testing, all with nonproprietary generic connectors to facilitate building code recognition. The design methodology and archetype development process are also discussed in this paper. A total of nine index buildings were developed from which 72 archetypes were extracted for this study. The archetypes were designed based on the design methodology and assessed with nonlinear pushover analysis and incremental dynamic analysis. Based on the required collapse margin, an R factor of 3 is proposed for CLT shear wall systems with 2∶1 or mixed aspect ratio panels up to 4∶1, and an R factor of 4 is proposed for CLT shear wall systems made up of only 4∶1 aspect ratio panels.