Seismic Performance of Cross-Laminated Timber and Cross-Laminated Timber-Concrete Composite Floor Diaphragms

Project Lead: Andre Barbosa

Project duration: 7/1/17 – 6/30/20


This project develops benchmark data needed to generate design guidelines for structural engineers to calculate strength & stiffness of CLT-diaphragms, with and without concrete toppings. The project includes a full-scale test of a two-story mass timber building at the UC San Diego shake table in collaboration with the larger project, “Development and Validation of a Resilience-based Seismic Design Methodology for Tall Wood Buildings” which features collaborators from throughout the western US and is funded by the Natural Hazards Engineering Research Infrastructure (NHERI) program of the National Science Foundation.

 

In the first year of this project, this was tested at the Natural Hazards Engineering Research Infrastructure outdoor shake table facility at the University of California San Diego in July 2017, collaborating with researchers of the NHERI TallWood Project. The shake table is able to simulate seismic activity to help researchers understand the effects on building materials. The tests were the first full-scale shake table tests ever performed in the U.S., and used all U.S- made materials. The tests performed on a two-story CLT building tested design assumptions of the CLT flooring systems and incorporated high-performance and resilient wall systems, known as self- centering rocking walls, that can guarantee structural integrity of the building both during and after an earthquake and during wind loading. In the second year of the project, the researchers are developing additional small scale testing to provide statistically significant understanding of the behavior of the connections designed and adopted in the full-scaled tested performed in 2017. This second wave of testing will provide the necessary data to develop the analytical simulations and design guidelines for diaphragms. In addition, the results from the tests done in 2017 are supporting the development of code language that will be balloted in 2019 for possible inclusion in the next version of the NDS.


Objectives

The main objective of the research is to develop the benchmark data needed to develop design guidelines for calculating strength and stiffness of CLT-diaphragms, with and without concrete toppings, and with and without the consideration of CLT-concrete composite action when concrete topping is present. To develop the data needed to validate design assumptions requires full-scale physical tests combined with analytical simulations, which are integral parts of this research project.