The report describes a new structural system in wood that is the first significant challenger to concrete and steel structures since their inception in tall building design more than a century ago. The introduction of these ideas is fundamentally driven by the need to find safe, carbon-neutral and sustainable alternatives to the incumbent structural materials of the urban world. The market for these ideas is quite simply enormous. The proposed solutions have significant capacity to revolutionize the building industry to address the major challenges of climate change, urbanization, sustainable development and world housing needs.
An overview on the mechanical and physical properties of cross laminated timber (solid wood
panels) in the building industry and its use in timber construction is presented. Structure-property
relations for solid wood based materials are discussed. Important properties, such as strength, sorption, diffusion, thermal conductivity in relation to the board structure are presented. By varying the structure, the properties can be optimized over a wide range. The focus of this publication lies on experimental works performed by Swiss researchers at the ETH Zürich.
Project contact is Frank Lam at the University of British Columbia
A continuous CLT floor/roof system that has two way bending action across multiple CLT panels will create open floor space with long spans in both major and minor directions, making mass timber construction more competitive and cost-effective. A design guide on CLT two way floor/roof system, incorporating the results from the two phases of study, will be developed at the end.
This volume presents a history of heavy timber construction (HTC) in the United States, chronicling nearly two centuries of building history, from inception to a detailed evaluation of one of the best surviving examples of the type, with an emphasis on fire resistance. The book does not limit itself in scope to serving only as a common history. Rather, it provides critical analysis of HTC in terms of construction methods, design, technical specifications, and historical performance under fire conditions. As such, this book provides readers with a truly comprehensive understanding and exploration of heavy timber construction in the United States and its performance under fire conditions.
With the advocacy for sustainable construction on the rise, use of timber as the main building material is being championed in large-scale construction projects. While the advancement of engineered timber products is addressing some issues that previously limited the use of wood in high-rise construction, there are still challenges such as fire and weather safety, code compliance and negative public perceptions. One main gap in the available resources is the lack of a comprehensive and detailed case study of a high-rise project with wood as the main construction material to capture constraints and innovations necessary in creating success, which has formed the direction of this research. This thesis is focused on documenting a case study of the Brock Commons project, an 18 storey, hybrid timber-concrete residential high-rise located at the University of British Columbia, Vancouver campus, which is the tallest hybrid timber building in the world. The overall research objective was to identify and document the delivery of this innovative project, with a specific emphasis on the innovations necessary to make timber high-rise construction successful and the use of VDC tools in the design and pre-construction process. The case study documents the project context, the design process, the business and industry drivers, and the motivation for construction. Moreover, it investigates the motivations for all stakeholders, identifies the challenges and constraints, and captures the innovative solutions that were utilized to ensure project success. The case study also documents the innovative use of VDC to support prefabrication and overall project coordination. Specifically, it investigates the role of the VDC integrators in the project, the paths of communications with the different project team members, and the inputs and outputs of each phase of design and construction. This research identified lessons learned that can be applied to other construction projects where timber is the main structural component and a heavy use of VDC and pre-fabrication is required. Use of timber and innovative methods in construction have been consistently rising in the past decade, and this research aims to provide a starting point for future efforts in mass timber high-rise construction.
The in-plane permeability was measured for thick, unidirectional oriented strand lumber made from aspen (Populus tremuloides) strands and pressed to five different densities. The press cycle was such that the vertical density profile of the panels was uniform. Specimens were cut from the boards and sealed inside a specially designed specimen holder; this jig was connected to a permeability measurement apparatus and in-plane permeability measured parallel, perpendicular, and 45° to the strand orientation. Permeability decreased markedly with increasing board density. The highest permeability was in the strand alignment direction and lowest perpendicular to it. The permeability in the 45° direction fell between those in parallel and perpendicular to strand alignment. A polynomial equation was fit to the results of each direction with r2 of 0.938 and 0.993. The in-plane distribution of permeability as a function of flow direction was obtained and its vector diagram was lenticular in shape.
Cross-laminated timber (CLT), a new generation of engineered wood product developed initially in Europe, has been gaining popularity in residential and non-residential applications in several countries. Numerous impressive low- and mid-rise buildings built around the world using CLT showcase the many advantages that this product can offer to the construction sector. This article provides basic information on the various attributes of CLT as a product and as structural system in general, and examples of buildings made of CLT panels. A road map for codes and standards implementation of CLT in North America is included, along with an indication of some of the obstacles that can be expected.
The use of mass timber in high rise construction is an innovation. Mass timber construction has influential benefits including a lower overall construction time, a lower environmental impact, the use of renewable resource and an improved aesthetics. Despite the mentioned benefits, mass timber is not the traditional material for low to mid-rise commercial, institutional and residential construction in Canada. This is partially due to the need to explore the efficiency of mass timber construction relative to traditional construction. Detailed quantitative documentation of successful construction projects assists organisations planning mass timber high-rise projects by understanding and quantifying the advantages to ensure the viability of the construction process. This research project aims to understand the performance of mass-timber construction in the context of a construction manager, particularly the time saved due to completion of structural and envelope systems early. The case study chosen for this thesis is the tallest mass timber hybrid building in the world: Tallwood House. The research team studied the project in a macro-level perspective to investigate the building elements as single entities. Moreover, a micro-level study focuses on the performance of every level of the following elements: mass timber structure, envelope cladding systems and cross-laminated timber drywall encapsulation. The macro-level study investigates: (1) The production rate of the various building elements, (2) The coordination between structural trades to build a heavily pre-fabricated building using a single crane, and (3) The labor efforts per discipline. Moreover, the micro-level study investigates: (4) The variability of productivity of all levels, (5) A statistical investigation of three factors on cross-laminated timber installation, (6) Schedule reliability of preliminary planned schedule relative to the construction schedule (actual progress), (7) Earned value analysis, and (8) Planned percent complete to study the reliability of weekly work plans relative to construction schedules. All metrics were validated by the senior project manager through a discussion and confirmation of the inputs, findings and conclusions drawn. The claimed contribution of this research is an advanced state of knowledge about mass timber by exploring the efficiency of the construction process.