Recipient Organization
OREGON STATE UNIVERSITY
(N/A)
CORVALLIS,OR 97331
Performing Department
(N/A)
Non Technical Summary
Building code officials and fire marshals often present concerns related to combustible construction that become barriers to the use of mass timber in their jurisdictions. Due to the lack of data on the decay phase and post-fire performance of mass timber structures, building code officials are hesitant to allow for the construction of mass timber buildings in cities throughout the US. This project focuses on the mass timber building performance in the decay phase of a fire, the post-fire behavior of mass timber buildings, and the emissions of mass timber buildings during a fire. These efforts are aimed at developing solutions for fire fighter safety in mass timber buildings and providing the first data related to carbon emissions for a structure.The results from this research will provide critical data for the development of engineered solutions for fire safe mass timber buildings (including firefighting) and the necessary input data to for carbon emission models and life cycle analysis. These solutions will alleviate technical and market barriers of using mass timber throughout the US and further the progression of building codes that permit the use of mass timber in high-rise building construction.Alleviating these technical barriers will benefit the economy in states and rural regions of the country where timber production is still the main economic driver thereby promoting the use of this natural resource. Specifically, this Integrated Project application addresses the NIFA AFRI priority areas of: bioenergy, natural resources, and environment and agriculture economics and rural communities.
Animal Health Component
25%
Research Effort Categories
Basic
60%
Applied
25%
Developmental
15%
Goals / Objectives
The overarching goal of the proposed research program is to generate technical data that will advance the use of both traditional wood products and emerging engineered wood products in building construction while improving the safety for building occupants and the surrounding community. The results of this research will be used to improve engineering design methodologies applicable to the new generation of wood structures and demonstrate the role these structures play in meeting the sustainability targets of the building construction industry.In the United States, wood is a common building material in low-rise residential construction. Recently, several technical and regulatory barriers have been eliminated through research and innovation to establish wood products as a viable building material for structures beyond low-rise residential structures. However, the consensus among stakeholders (producers, regulators, material specifiers, designers, builders, and insurers) is that some major technical challenges remain Specifically, in the structural performance of wood during all phases of a fire, emissions from buildings using combustible construction, and inadequate quantification of environmental impacts of wood construction. The multi-scale and multi-disciplinary research program proposed herein is designed to address the challenges in a holistic and systematic manner. This project will address the current technical barriers thereby increasing the use of wood products in construction in the United States and leading to socio-economic benefits that help quantify, and ultimately reduce, greenhouse gas (GHG) emissions from the construction sector.
Project Methods
Three sets of experimental tests will occur at different scales. This multi-scale test series will be leveraged to calibrate modeling capabilities, develop new knowledge on the behavior of mass timber buildings in fire, and develop new design methodologies for fire safety in mass timber buildings. To simulate the fire performance of mass timber buildings, this requires modeling of the fire within the compartment, heat transfer within the mass timber structural component in response to the fire, and then using the temperatures from the heat transfer analysis, simulating the structural response of the mass timber element. These simulations refer to the fire model, thermal model, and structural model, respectively. These models, coupled with emissions data, provide a holistic response of a mass timber structure to fire.The experimental work will begin with large-scale compartment fire tests. The project team will construct three, single-floor mass timber compartments with 5-ply CLT walls and ceilings and glulam beams and columns under the large HRR hood at the NRFL. These tests will be carried out via an interagency agreement between FPL and NIST. The proposed structures will be 9 ft in length by 19 ft in depth, with a height of 8 ft, which adheres to the required compartment size per Standard for Performance-Rated Cross-Laminated Timber. Even though structural loads will not be applied throughout the tests, the compartments will be designed as though the compartment was a part of a high-rise mass timber building. The mass timber will be sourced from US-based suppliers, who see these fire tests as an important part of future mass timber adoption.The test structures will be highly instrumented to gain insight into important parameters during the fire and in the decay and cooling phases, including:Mass loss to determine combustible fuel consumption by the fire including the mass timber, when exposed in tests 2 and 3 using load cells placed under the specimens to measure change in weight of the specimen throughout the fire.HRR to evaluate the fire growth by measuring changes in oxygen, carbon monoxide, and carbon dioxide from the full structure.Compartment and material temperatures using thermocouple trees and embedded thermocouples, respectively.Radiative heat flux to mass timber elements measured with water-cooled heat flux sensors and plate thermometers.Infrared cameras to detect smoldering as a function of time post-fire event.Emissions both inside and escaping from the compartment to capture the full range of combustion conditions.Evaluation of charred mass timber from various locations in the compartment using advanced characterization techniques to obtain material properties and quantify physical changes due to location in the compartment and smoldering.The intermediate-scale specimens will verify if the data collected in the large-scale compartment fire tests, including emissions, can be scaled. Scaling the data is critical for the broader applicability of the experimental results to a wide range of compartments and buildings that are being constructed globally. The scaled specimens will be constructed and tested at FPL's laboratory under the 3MW hood and will be approximately 1/8 to 1/4 of the full-size tests with similar instrumentation for data collection. The control test for the intermediate scale will be the same as the control testfor the large-scale tests. The mass timber will be fully encapsulated with non-combustible boards and the fuel will be by a gas burner within the compartment to control the fuel load and ensure scaling. The fuel load in the compartment will be scaled based on the area of the compartment such that the ratio of the fuel load to the summation of the areas of walls, floors, and ceiling for the intermediate-scale and large-scale compartments are the same.The small, bench-scale experiments will utilize the cone calorimeter located at USDA's Forest Products Laboratory. While large-scale tests provide a significant amount of data, they are expensive and cumbersome. Cone calorimeter testing is often referred to as bench-scale testing and allows many samples to be tested, and parametric studies to be undertaken at less cost. By applying the results from the large and intermediate scale tests, such as the heat flux and atmosphere, in a cone calorimeter, the strengths and limitations of scaled approaches regarding fire performance and emissions can be further evaluated and assessed. The cone calorimeter typically obtains the release rate (includes measurement of O2, CO2 and CO gases), ignition time, mass loss rate, specific extinction area, and effective heat of combustion.The thermal profile in the specimens will be determined with thermocouples located within timber specimens, consistent with the large and intermediate scale testing, with the aim of replicating, at the bench-scale (small scale), results from the large and intermediate scale testing. For these studies, the cone calorimeter will be coupled with FTIR and samplers to collect particulate matter to measure the products of combustion and a controlled atmosphere attachment.