An Approach to CLT Diaphragm Modeling for Seismic Design with Application to a U.S. High-Rise Project

This paper applies knowledge of cross-laminated timber (CLT) diaphragm behavior to practical engineering design to meet the requirements of high-seismic design in the U.S. In particular, it focuses on modeling of CLT diaphragms to calculate deflections and distribute forces resulting from earthquake loading. 

A candidate CLT diaphragm analysis model approach is presented and evaluated as an engineering design tool motivated by the needs of seismic design in the U.S. The modeling approach consists of explicitly modeling CLT panels as discrete orthotropic shell elements with connections between panels and connections from panels to structural framing modeled as two-point springs. The modeling approach has been compared to a developed CLT diaphragm design example based on U.S. standards showing the ability to obtain matching deflection results. The sensitivity of the deflection calculations to considering CLT panel-to-panel connection gap closure is investigated using a simple diaphragm example. The proposed modeling approach is also applied to a candidate floor diaphragm design for a tall timber building. Observations from this effort are that the proposed method, while a more refined model than typically used during building design, shows promise to meet the needs of innovative CLT seismic designs where appropriate simpler diaphragm models are not available.