Fire Performance of CLT and NLT Timber-Concrete, Composite Floors
Project Lead:
Erica Fischer – Oregon State University (OSU), School of Civil and Construction Engineering
André Barbosa – OSU School of Civil and Construction Engineering
Arijit Sinha – OSU Department of Wood Science and Engineering
Design Advisory Group:
SOM, KPFF, Aspect Engineers
Research Advisory Group:
TallWood Design Institute, Katerra, ARUP, Cairn Pacific, Forest Products Laboratory (FPL)
Project Duration:
2018-2020
2018-2020
Facilities:
National Research Council Canada (NRC)
Abstract
Cross-laminated timber (CLT) and Nail-laminated timber (NLT) floors are sometimes designed with a concrete topping that improves structural, acoustic and vibration performance. Recently, engineers are taking advantages of these concrete toppings to increase spans. There has been minimal research to examine the effect of the concrete topping on the fire performance of the composite system. Preliminary studies suggest that these composite floors may provide higher fire resistance, which could open up new market opportunities for mass timber products in buildings.
Introduction
The primary stages of this project include:
- Testing the fire performance of loaded CLT- and NLT-composite floor assemblies (preliminary test: February 2019). Data from this phase will be used to improve products, generate design guidelines, and to benchmark numerical modeling techniques that can test additional parameters for the fire performance of timber-concrete composite floor systems.
- Validating a new fire testing setup at Oregon State University that could allow for better experimental flexibility and lowered costs.
In order to develop a comprehensive analysis of such composite systems, the fire-tested assemblies matched those being tested by Dr. Andre Barbosa (Project: Seismic Performance of Cross-Laminated Timber and Cross-Laminated Timber-Concrete Composite Floor Diaphragms, 2017-2020) and Dr. Chris Higgins (Project: Composite Concrete-CLT Floor Systems for Tall Building Design, 2017-2020).
Research Details
An iterative procedure is used to optimize both, the CLT layup and the structural engineering design of the structure, for which the panels are produced. The material/element level analysis is aimed at the determination of mechanical properties and design values of low-value PP CLT generated by the forest restoration programs, which are needed as input for the analytical prediction of the engineering characteristics of prototype CLT layups. The material level analysis is currently focused on bond integrity tests as well as long- and short-beam bending tests. CLT panel prototypes for these tests are fabricated in the OSU A.A. Emmerson pilot plant. Once a viable prototype is developed, the full-size test panels will be produced by CLT manufacturers in the Pacific Northwest region.
Research Details
Fire exposure: ASTM E119 fire
Loading: 80 lb/ft2 sustained load
Failure criteria: Loss of load-carrying capacity
Mass timber products being tested:
Cross laminated timber (CLT):
Grade of lumber: Spruce-Pine-Fir (SPF), V2 Grade
Panel dimensions: width 4’-0”, length 16’-0”
Topping: 2.25” concrete, connected with self-tapping screws
Nail laminated timber (NLT):
Grade of lumber: Spruce-Pine-Fir, No. 2,
Panel dimensions: width 4’-0”, length 16-0”, 2”X6” nominal lumber
Topping: 3” concrete, connected by Mitek truss plates
Future Work
- Shear connector tests to quantify the force-slip behavior of the shear connectors in both systems
- Benchmark finite element modeling techniques
- Develop testing capabilities at Oregon State University
Contact: erica.fischer@oregonstate.edu