Force Modification Factors for CLT Structures for NBCC

Abstract

Cross-laminated timber (CLT) as a structural system is not introduced in European or North American building codes, and there is limited information available on the seismic factors for design of such structures. The objective of the study was to derive suitable ductility-based force modification factors (Rd-factors) for seismic design of CLT buildings in the National Building Code of Canada (NBCC). For that purpose, the well-known six-storey NEESWood Capstone wood-frame building was redesigned as a CLT structure. Non-linear analytical models of the building designed with different Rd-factors were developed using the SAPWood program. CLT walls were modeled using the output from mechanics models developed in Matlab that were verified against CLT wall tests conducted at FPInnovations. Each of the 48 building models was subjected to a series of 22 bi-axial input earthquake motions suggested in the FEMA P-695 pro cedure. Results showed that an Rd-factor of 2.0 is appropriate for the building studied.