FPInnovations conducted a research project to study the construction of mid-rise wood exit shafts in Ontario and Québec. The scope of the project included an investigation into the concerns that have been raised in regards to the use of wood exits in mid-rise buildings, an analysis of recent Canadian fire statistics in residential multi-family structures, and a fire demonstration of a mass timber wall and supported light-frame floor. This report describes the fire demonstration completed as part of this project; this report acts as a supplement to the full project report.
FPInnovations carried out a survey with consultants and researchers on the use of analytical models and software packages related to the analysis and design of mass timber buildings. The responses confirmed that a lack of suitable models and related information for material properties of timber connections, in particular under combination of various types of loads and fire, was creating an impediment to the design and construction of this type of buildings. Furthermore, there is currently a lack of computer models for use in performance-based design for wood buildings, in particular, seismic and fire performance-based design.
In this study, a sophisticated constitutive model for wood-based composite material under stress and temperature was developed. This constitutive model was programmed into a user-subroutine and can be added to most general-purpose finite element software. The developed model was used to model the structural performance of a laminated veneer lumber (LVL) beam and a glulam bolted connection under force and/or fire. Compared with the test results, it shows that the developed model was capable of simulating the mechanical behaviour of LVL beam and glulam connection under load and/or fire with fairly good correlation.
With this model, it will allow structural designers to obtain the load-displacement curve of timber connections under force, fire or combination of the two. With this, key design parameters such as capacity, stiffness, displacement and ductility, which are required for seismic or fire design, can be obtained.
It is recommended that further verification and calibration of the model be conducted on various types of wood products, such as CLT, glulam, SCL and NLT, and fasteners, e.g. screw and rivet. Moreover, a database of the thermal and structural properties of the wood members and fasteners that are commonly used in timber constructions need to be developed to support and facilitate the application of the model.
Currently, mass timber building designs commonly incorporate a concrete floor topping. This can improve building accoustics by increasing the mass of the assembly, reduce floor vibration and create a smooth flat surface to install finish flooring on. The installation of concrete requires formwork, pouring and finishing the concrete and time to cure which adds to project schedules. One way to address this is to use mass timber elements that are prefabricated with concrete toppings preinstalled. Replaceing the concrete floor toppings wiht dry alternatives, such as cement board, may also reduce construction timelines, while still ensuring adequate acoustic and vibration performance. Cement board needs only to be screwed in place and can be walked on immediately after installation; this reduction in construction time may reduce overall project costs and help make wood buildings more cost competitive than other types of construction.
The objective of this work is to generate fire resistance data for NLT assemblies to address significant gaps in technical knowledge. This research will support designers and builders in the use of mass timber assemblies in larger and taller buildings, as well as provide scientific justification for Authorities Having Jurisdiction (AHJ) to review and accept this construction method. The intent is to demonstrate that NLT construction can meet or exceed NBCC fire safety requirements for use in buildings of mass timber construction.
The data could be used towards the inclusion of an NLT fire resistance calculation methodology into Annex B of CSA O86 – Engineering Design for Wood , which currently addresses only glue-laminated timber (GLT), structural composite lumber (SCL) and cross-laminated timber (CLT).
The objective of the current project is to develop a performance-based design process for wood-based design systems that would meet the objectives and functional statements set forth in the National Building Code of Canada.
More specifically, this report discusses the fire and seismic performance of buildings, as identified as a priority in a previous FPInnovations report.
The objective of this research is to evaluate CLT face-bonded with adhesives that meet the new 2018 ANSI/APA PRG 320 with respect to elevated temperature requirements and their effects on the resulting charring rates when exposed to the standard time-temperature curve of CAN/ULC S101 (similar exposure to ASTM E119). The results can ultimately be used to propose modifications to the charring models currently used in CSA O86-14 and the NDS, if found conclusive.
This project assesses the fire resistance of laminated timber structural systems as wall and floor assemblies. Full-scale tests were conducted to assess structural fire resistance and charring behaviour. This research could be used to expand current fire design provisions and support inclusion of these types of assemblies into Annex B of CSA O86.
WoodST is capable of calculating heat transfer, charring rate, load-displacement curve as well as the time and mode of failure of timber structures exposed to fire, thus providing a cost-competitive solution for the fire safety analysis of timber structures. This InfoNote briefly introduces the development and verification of WoodST. Two applications of WoodST are also demonstrated.
WoodST est capable de calculer le transfert de chaleur, la vitesse de carbonisation, la courbe charge-déplacement ainsi que le moment et le mode de défaillance des structures en bois exposées au feu, offrant ainsi une solution à coût compétitif pour l'analyse de la sécurité incendie des ossatures en bois. La présente note d’information présente brièvement le développement et la vérification de WoodST. Deux applications de WoodST sont également présentées.