This study on Circular Economy & the Built Environment Sector in Canada was carried out by The Delphi Group in collaboration with Scius Advisory and completed in March 2021 on behalf of Forestry Innovation Investment Ltd. (FII) in British Columbia and Natural Resources Canada (NRCan) as the co-sponsors for the research. The work identifies a broad range of current efforts across Canada and undertakes a deeper dive on design for disassembly and adaptability (DfD/A) best practices, including an analysis of the ISO Standard 20887:2020 (i.e., design for disassembly and adaptability) in line with current Canadian industry practice and market readiness.
Timber has been used for building construction for centuries, until the industrial revolution, when it was often replaced by steel and concrete or confined to low-rise housings. In the last thirty years however, thanks to the development of mass timber products and new global interest in sustainability, timber has begun to make a resurgence in the building industry. As building codes and public perception continues to change, the demand for taller and higher-performance timber buildings will only grow. Thus, a need exists for new construction technology appropriate for taller mass timber construction, as well as for fabrication and deconstruction practices that respect wood’s inherent sustainable nature. With this in mind, this research program aims to develop a new hybrid shear connection for mass timber buildings that allows for easy construction, deconstruction, and reuse of the structural elements.
This report includes results of Phase 1, which focused on connections consisting of partially threaded 20M and 24M steel rods bonded into pockets formed in CLT and surrounded by thick crowns of high-strength three-component epoxy-based grout. A total of 168 specimens were designed and fabricated, and push-out shear tests carried out with a displacement-controlled monotonic loading protocol. Strength and stiffness values were assessed and effective failure modes in specimens identified. These latter, along with the recorded load-deformation curves, indicate that it is possible to develop mechanics-based design models and design formulas akin to those already used for typical dowel-type fastener timber connections. Additionally, the specimens were easily fabricated in the lab and quickly fastened to the test jig by means of nuts and washers, suggested such connections have a strong potential for prefabrication, disassembly, and reuse.
The Italian building heritage is aged and inadequate to the high-performance levels required nowadays in terms of energy efficiency and seismic response. Innovative techniques are generating a strong interest, especially in terms of multi-level approaches and solution optimizations. Among these, Nested Buildings, an integrated intervention approach which preserves the external existing structure and provides a new structural system inside, aim at improving both energy and structural performances. The research presented hereinafter focuses on the strengthening of unreinforced masonry (URM) buildings with cross-laminated timber (CLT) panels, thanks to their lightweight, high stiffness, and good hygrothermal characteristics. The improvement of the hygrothermal performance was investigated through a 2D-model analyzed in the dynamic regime, which showed a general decreasing in the overall thermal transmittance for the retrofitted configurations. Then, to evaluate the seismic behavior of the coupled system, a parametric linear static analysis was implemented for both in-plane and out-of-plane directions, considering various masonry types and connector spacings. Results showed the efficiency of the intervention to improve the in-plane response of walls, thus validating possible applications to existing URM buildings, where local overturning mechanisms are prevented by either sufficient construction details or specific solutions. View Full-Text
This paper presents an innovative and sustainable timber constructive system that could be used as an alternative to traditional emergency housing facilities. The system proposed in this study is composed of prefabricated modular elements that are characterized by limited weight and simple assembly procedures, which represent strategic advantages when it comes facing a strong environmental disaster (e.g. an earthquake). The complete dismantling of structural elements and foundations is granted thanks to specific details and an innovative connection system called X-Mini, capable of replacing traditional anchoring devices (i.e. hold downs and angle brackets) by resisting both shear and tension loads. This constructive system, denoted as Hybrid Timber Frame (HTF), takes advantage of the strong prefabrication, reduced weight of light-frame timber systems, and of the excellent strength properties of the Cross Laminated Timber (CLT) panels. Specifically, the solid-timber members typically used in the structural elements of light-frame systems are replaced by CLT linear elements. The results of experimental tests and numerical simulations are critically presented and discussed, giving a detailed insight into the performance of the HTF under seismic conditions.
As woodworking and construction technologies improve, the construction of multi-storey timber buildings is gaining popularity worldwide. There is a need to look at the design of existing buildings and assess their sustainability. The aim of the present study is to assess the sustainability of modern high-rise timber buildings using multi-criteria assessment methods. The paper presents a hierarchical system of sustainability indicators and an assessment framework, developed by the authors. Based on this framework, the tallest timber buildings in different countries, i.e., Mjøstårnet in Norway, Brock Commons in Canada, Treet in Norway, Forte in Australia, Strandparken in Sweden and Stadthaus in UK, were compared across the three dimensions of sustainability (environmental, economic/technological, and social). Research has revealed that none of the buildings is leading in all dimensions of sustainability. However, each building is unique and has its own strengths. Overall multi-criteria assessment of the buildings revealed that the Brock Commons building in Canada has received the highest rank in all dimensions of sustainability. The paper contributes to the theory and practice of sustainability assessment and extends the knowledge about high-rise timber buildings. The proposed sustainability assessment framework can be used by both academics and practitioners for assessment of high-rise timber buildings.
The acceptable solutions in Division B of the anticipated 2020 NBCC limit the height of Groups C and D buildings of sprinklered encapsulated mass timber construction (EMTC) to 12 storeys in building height, and a measured building height of 42m. The recently published 2021 IBC contains provisions to permit buildings of mass timber construction under the IBC Type IV construction, surpassing the NBCC provisions by maximum building height, building area, occupancy groups, and interior exposed timber. The IBC mass timber buildings are permitted to have a building height of maximum 18 storeys, depending on the occupancy group. Within Type IV construction, four subdivisions are described to have varying maximum permissible building height, area, fire resistance rating (FRR), and interior exposed timber.
Through a comparison of mass timber provisions of both Codes, relevant research reports, test reports, industry standards, this report documents the consequential and inconsequential differences and developed conclusions on whether the NBCC can adopt the IBC provisions, and with what modifications so that the new provisions may fit the NBCC context.
Construction of eco-friendly high-rise buildings using cross-laminated timber (CLT)-concrete composite (CCC) slabs is increasing. CLT and concrete, which are major component materials of the CCC slab, are significantly affected by moisture. In particular, the moisture content of concrete in the production process affects the quality of both materials. In this study, the effects of the wet construction method on CLT and concrete component materials are examined by monitoring the behavior of the CCC slab during curing time (28 d) and by evaluating the quality of the concrete and CLT after curing. When manufacturing the CCC using the wet construction method, moisture penetration from the concrete into the CLT during the curing time is suppressed by the shear bonding between the concrete and the CLT when an adhesive is used. This minimizes the effect of the moisture on both component materials, consequently yielding uniform compressive strength to the concrete after curing and preventing the deterioration of the CLT’s delamination performance. Therefore, the shear bonding method using an adhesive is expected to minimize the quality deterioration observed in concrete and CLT after curing.
Advanced sustainable lateral load resisting systems that combine ductile and recyclable materials offer a viable solution to resist seismic load effects in environmentally responsible ways. This paper presents the seismic response of a post-tensioned timber-steel hybrid braced frame. This hybrid system combines glulam frame with steel braces to improve lateral stiffness while providing self-centreing capability under seismic loads. The proposed system is first presented. A detailed numerical model of the proposed system is then developed with emphasis on the connections and inelastic response of bracing members. Various types of braced frames including diagonal, cross and chevron configurations are numerically examined to assess the viability of the proposed concept and to confirm the efficiency of the system. A summary of initial findings is presented to demonstrate usefulness of the hybrid system. The results demonstrate that the proposed system increases overall lateral stiffness and ductility while still being able to achieve self-centring. Some additional information on connection details are provided for implementation in practical structures. The braced-frame solution is expected to widen options for lateral load resisting systems for mid-to-high-rise buildings.
International Journal of Design & Nature and Ecodynamics
Technological developments and social trends can create demand for new building functionalities, necessitating the adaptation of existing buildings. This paper presents the development of a modular building structural system that provides for the harmonization between the structural and functional lifespans of a building in order to achieve greater sustainability. The limitations of the existing prefabricated urban buildings with respect to their adaptability are contrasted with the proposed solution. The use of prefabricated engineered materials, such as cross laminated timber (CLT) and CLT-concrete composites, in conjunction with a modular system, reduces any climatic effects. The inherent advantages of incorporating detachable connections allows for the necessary structural adaptability, subsequently harmonizing and elongating the structural and functional lifespans. The resulting sustainable concept, when applied to residential buildings, could serve as a solution to address projections of future urban growth.
This paper reflects on the structural design of Haut; a 21-storey high-end residential development in Amsterdam, the Netherlands. Construction started in 2019 and is in progress at the time of writing. Upon completion in 2021, Haut will be the first residential building in the Netherlands to achieve a 'BREEAM-outstanding' classification. The building will reach a height of 73 m, making it the highest timber structure in the Netherlands. It contains some 14.500 of predominantly residential functions. It features a hybrid concrete-timber stability system and concrete-timber floor panels. This paper describes the concepts behind the structural design for Haut and will touch upon the main challenges that have arisen from the specific combination of characteristics of the project. The paper describes the design of the stability system and -floor system, the analysis of differential movements between concrete and timber structures and wind vibrations. The paper aims to show how the design team has met these specific challenges by implementing a holistic design approach and integrating market knowledge at an early stage of the design.