Project contact is Erol Karacabeyli at FPInnovations
To support NRCan's Tall Wood Building Demonstration Initiative, FPInnovations developed and published the 2014 Edition of Technical Guide for the Design and Construction of Tall Wood Buildings in Canada. More than 80 technical professionals comprised of design consultants and experts from FPInnovations, the National Research Council, the Canadian Wood Council and universities were involved in its development. The Guide has gained national and worldwide reputation as one of the most complete and credible documents helping to introduce to the design and construction community, and Authorities Having Jurisdiction the terms "Mass Timber Construction" and "Hybrid Tall Wood Buildings".
Since the publication of the First Edition, a number of tall wood buildings have been designed and constructed. Substantial regulatory changes are expected to happen based on the experience obtained from the demonstration initiative and the extensive research that has taken place domestically and internationally since the publication of the First Edition. These developments highlight a need for the Guide to be updated so that it aligns with efforts currently underway nationally and provincially and continues to lead in providing the design and construction community technical insight into new opportunities for building in wood.
The First Edition of the Guide helped to focus the efforts of the early adopters who participated in NRCan's Tall Wood Building Demonstration Initiative. Updating and aligning the Guide with the release of the new National Building Code of Canada and the Canadian wood design standard (CSA O86), and sharing the experiences gained from tall wood buildings built since the First Edition, will not only continue to expand the base of early adopters, but also help to move aspects of mass timber and hybrid wood buildings into the mainstream.
This article outlines the structural design approach used for the Brock Commons Student Residence project, an 18-storey wood building at the University of British Columbia in Vancouver, Canada. When completed in summer 2017, it will be the tallest mass timber hybrid building in the world at 53 meters high. Fast + Epp are the structural engineers, working in conjunction with Acton Ostry Architects and Hermann Kaufmann Architekten. Total project costs, inclusive of fees, permits etc. are $51.5M CAD.
The present work aims to define horizontal joint dimension tolerances for newly proposed prefabricated façade systems for applications in tall cross laminated timber (CLT) buildings based on the compression perpendicular to grain characteristics of the component. This requires a thorough understanding of structural settlement under vertical loads which can vary at each floor height. An experimental program has been carried out with reference to the case of a platform frame building construction, where major perpendicular to grain compression of the floor can occur under high loads. Five-layer CLT specimens have been tested under compression via the application of a line load with steel plate as well as actual CLT wall specimens. Strengthening contribution using full threaded self-tapping wood screws has also been investigated. Results of deformation characteristics have been validated through a non-linear finite element analysis and further elaborated in order to outline implications in the design of a prefabricated façade.
Cross-Laminated Timber is one of the most widely used engineered wood products, thanks to its numerous advantages, among which construction speed is the most appreciated, both by clients and by designers. However, construction scheduling compression refers exclusively to CLT structures, while the rest of the construction process still requires a longer phase to complete vertical enclosures. The aim of the research work presented in this paper is to outline advantages brought about when the degree of envelope prefabrication of tall timber buildings is increased. Results are presented in two sections. The first includes the definition of a case study together with an overview of possible technical details for entirely prefabricated façade solutions, ready to be installed without the need to work via scaffolds. The second deals with construction site management analysis for the case study building, where the determination of specific factors having an influence on time and costs is achieved by varying the prefabrication degree of the various façade configurations and repeating the analysis process. The main findings of this research work demonstrate that comprehensive façade prefabrication allows not only consistent compression of construction scheduling to be achieved, but also for immediate protection of wooden elements from weather agents.
This paper describes the design of a novel semi-prefabricated LVL-concrete composite floor that has been developed in New Zealand. In this solution, the floor units made from LVL joists and plywood are prefabricated in the factory and transported to the building site. The units are then lifted onto the supports and connected to the main frames of the building and to the adjacent units. Finally, a concrete topping is poured on top of the units in order to form a continuous slab connecting all the units. Rectangular notches cut from the LVL joists and reinforced with coach screws provide the composite action between the concrete slab and the LVL joists. This system proved to be an effective modular solution that ensures rapid construction. A design procedure based on the use of the effective flexural stiffness method, also known as the “gamma method” is proposed for the design of the composite floor at ultimate and serviceability limit states, in the short and long term. By comparison with the experimental results, it is shown that the proposed method leads to conservative design. A step-by-step design worked example of this novel semi-prefabricated composite floor concludes the paper.
Project contact is Frank Lam at the University of British Columbia
The objective of this project is to develop a large span timber-based composite floor system for the construction of highrise office buildings. This prefabricated floor system could span over 10 m under regular office occupation load, and its use will expedite the construction significantly, converting to multi-million financial savings in a typical 40+ story project, besides the impact on reducing carbon footprint and enhancing living experience.
This thesis examines the development of a superstructure for a slab-on-girder wood-concrete composite highway bridge. Wood-concrete composite bridges have existed since the 1930's. Historically, they have been limited to spans of less than 10 m. Renewed research interest over the past two decades has shown great potential for longer span capabilities. Through composite action and suitable detailing, improvements in strength, stiffness, and durability can be achieved versus conventional wood bridges. The bridge makes use of a slender ultra-high performance fibre-reinforced concrete (UHPFRC) deck made partially-composite in longitudinal bending with glued-laminated wood girders. Longitudinal external unbonded post-tensioning is utilized to increase span capabilities. Prefabrication using double-T modules minimizes the need for cast-in-place concrete on-site. Durability is realized through the highly impermeable deck slab that protects the girders from moisture. Results show that the system can span up to 30 m while achieving span-to-depth ratios equivalent or better than competing slab-on-girder bridges.
The design-build of a Wooden Adaptive Architectural System is part of a larger research-creation project on Adaptive Architecture (AA)  exploring the entire design process leading to a fully adaptable three story high 1:3/4 wooden structure. This system allows the easy manoeuvrability by the occupants of walls and floors in x, y and z directions in order to adapt the space to their environmental and functional needs. The omnidirectional mobility criteria challenged conventional building techniques and led to an innovative all-wood rigid node. Extensive prototyping using digital fabrication allowed the team to optimize the node assemblage and precision through parametric experimentation before proper production. The Wooden Adaptive Architectural System, made of 2000 prefabricated sticks measuring as little as 1 ¾” x 1 ¾” x 24” provides fully adaptive space configurations and be easily deconstructed, transported, and reassembled in totally new building shapes.
Project contact is Luca Sorelli at Université Laval
Hybrid wood-concrete structures are emerging in the multi-storey wood building market, as they provide effective solutions in terms of lightness, rigidity, vibration and fire resistance (Yeoh et al., 2010, Dagenais et al., 2016). This project aims to reduce the cost of these hybrid floors by reducing the time of construction by prefabrication technology with emphasis on use. In addition, the goal is to explore the use of Ultra High Performance Fiber Composite Concrete (UHPC) to reduce the thickness of the wood slab, and also the use of ductile connections to increase the reliability of the floor (Habel and Gauvreau). 2008, Zhang and Gauvreau 2014, Auclair-Cuerrier et al 2016a). Finally, the concrete slab improves the diaphragm behavior of the floor to seismic actions.