This project proposes a timber-based composite floor that can span 12 m and be used in the construction of 40+ story office buildings. This floor system integrates timber panels and timber beams to form a continuous box girder structure. The timber panels function as the flanges and the timber beams as the web. The beams are spaced and connected to the flange panels so that sufficient bending stiffness of a 12 m span can be achieved via the development of composite action.
The current phase of this project studied the performance of the connections between timber elements in the proposed composite member. Six types of connections using different flange material and connection techniques were tested: Cross Laminated Timber (CLT), Laminated Strand Lumber (LSL), Laminated Veneer Lumber (LVL), and Post Laminated Veneer Lumber (PLVL). Glulam was used as the web. The majority of the connections used self-tapping wood screws except one had notches. The load-carrying capacity, stiffness, and ductility of the connections were measured. The stiffness of CLT, LSL, and PLVL connections was in the same range, 19-20 kN/mm per screw. Amongst the three, LSL had the highest peak load and PLVL had the highest proportional limit. The stiffness of the two LVL screw connections was around 13 kN/mm. The notched LVL connection had significantly higher stiffness than the rest, and its peak load was in the same range as LSL, but the failure was brittle.
LVL was used to manufacture the full scale timber composite floor element. With a spacing of 400 mm, the overall stiffness reached 33689 N
mm2×109, which was 2.5 times the combined stiffness of two Glulam beams. The predicted overall stiffness based on Gamma method was within 5% of the tested value, and the estimated degree of composite action was 68%. From both the test results and analytical modeling, the number of screws may be further reduced to 50% or less of the current amount, while maintaining a high level of stiffness.
Future work includes testing the composite floor under different screw spacings,
investigating the effect of concrete topping, and the connections between floor members
and other structural elements.
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.
Numerous countries across the globe have witnessed the recent decades’ trend of multi-storey timber buildings on the rise, owing to advances in engineering sciences and timber construction technologies. Despite the growth and numerous advantages of timber construction, the global scale of multi-storey timber construction is still relatively low compared to reinforced concrete and steel construction. One of the reasons for a lower share of high-rise timber buildings lies in the complexity of their design, where the architectural design, the selection of a suitable structural system, and the energy efficiency concept strongly depend on the specific features of the location, particularly climate conditions, wind exposure, and seismic hazard. The aforementioned shows the need for a comprehensive study on existing multi-storey timber buildings, which correspond to the boundary conditions in a certain environment, to determine the suitability of such a construction in view of its adjustment to local contexts. Apart from exposing the problems and advantages of such construction, the current paper provides a brief overview of high-rise timber buildings in Europe. Moreover, it addresses the complexity of the design approach to multi-storey timber buildings in general. The second part of the paper highlights the importance of synthesising the architectural, energy, and structural solutions through a detailed analysis of three selected case studies. The findings of the paper provide an expanded view of knowledge of the design of tall timber buildings, which can significantly contribute to a greater and better exploitation of the potential of timber construction in Europe and elsewhere.
More and more people live in cities. The building industry is responsible for 33% of waste production and is set to increase further to 50% in 2025. The energy efficiency is continuously increased, but the waste production at the end of life of a building is largely ignored. This design proposes a solution in the form of a zero-waste high-rise design. It uses only recyclable or renewable materials. Mass-timber is chosen as the main material as it is not only renewable and easily reusable, it is also a storage of CO2. The design reuses the foundation of existing buildings, and with the lightweight properties of mass-timber, increases the density on the location by building taller. The design is four times taller as the current buildings. To allow for sustainable densification, the design offers public and collective qualities. The building has been designed is such a way to be easily refitted during its life cycle or to be completely disassembled at the end of life.
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.
International Conference on New Advances in Civil Engineering
Research Status
Complete
Series
IOP Conference Series: Materials Science and Engineering
Summary
Related to sustainability movement and minimizing the carbon footprint, timber structures are becoming more attractive. Wood, as main structural material, offers many benefits relate mostly to economic and ecological aspects, compared to other materials as steel or concrete. On the other hand, physical characteristics of wood complicate the usage of a timber for high-rise or large-span structures. It brings a new challenge for architects and engineers to deliver feasible solution for usability of timber, despite its features. One of the possible solutions could be implementation of CLT (Cross-Laminate Timber) panels in structural systems developed earlier for buildings made of prefabricated concrete slabs. SOM in cooperation with Oregon State University are currently testing composite slabs made of CLT and thin concrete layer reinforcing the wood and protecting it from fire. Although the system solution looks promising, and could bring the result, slabs limit using of the space in layout. On the other hand, frame structures would be much more efficient. This article comes up with an idea of modular frame structure, which could help to solve the problem. The scheme is based on "gridshell" type systems, where rods form a more efficient shell for dealing with stress forces.
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.
The intent of this project is to research evaluation and rehabilitation methods that are applicable to mass timber structures following a fire. This includes addressing both fire damage and water damage from sprinkler activation and/or the use of firefighting hoses. This report provides an overview of the type of damage that might be expected following a fire and methods that might reduce potential damage (including design elements and firefighting tactics). Current and existing rehabilitation methods for wood construction will be reviewed and their applicability to mass timber structures will be discussed. This includes the ability to conduct condition assessments and repairs on building elements that can be done in place. The overall objective is to reduce uncertainty related to mass timber construction, which ultimately would allow for more accurate risk evaluation by insurance companies.
Due to the inherent inefficiencies in conventional approaches followed in the construction industry and the global demand for lean and sustainable construction techniques, modular construction has witnessed a resurge especially in high-rise buildings. As such, much efforts have been put in studying the use of mass timber for the main structure of high-rise buildings in order to ensure more sustainable developments with high levels of adaptability. In this regard, previous research efforts have primarily focused on the added benefits of mass timber, its structural design and performance, and associated safety requirements. However, owing to the novelty in combining modular processes with timber materials and associated lack of data, several regulatory barriers and contractual issues still exist. To mitigate these issues, this paper studies the specifics of permit approvals and contracting issues in timber high-rise modular buildings. The objective is to develop a comprehensive up-to-date review and analysis of the relevant practices and to conduct interviews with industry experts to analyze their concerns, given the insufficient number of guides and building codes that dealt with these issues. Hence, our study investigates the process of obtaining permit approvals from local jurisdictions in Ontario in addition to the requirements for submission of additional documentation, engineering analysis, and testing. Moreover, it analyzes the initial stage of contractual agreement of stakeholders under the uncertainties imposed on these buildings and evaluates the suitability of Integrated Project Delivery (IPD) contracting method. Presenting detailed analysis of the initial planning stages for timber high-rise modular buildings can in turn suggest the best practices to be taken into consideration for the successful implementation of these buildings under the current building code.
In order to expedite market acceptance and facilitate the commercial uptake of wood products and systems in Canada, it is necessary to showcase such applications through high-rise and non-residential building demonstration projects. This paper presents recent initiatives by the Government of Canada focused on increasing use of wood as a green building material in infrastructure projects by supporting such demonstration projects. The objective of Green Construction through Wood (GCWood) program (launched in 2017) is to support the design and construction of several high-rise and non-residential timber demonstration buildings and bridges in Canada through expression of interest (EOI) calls. The program is also supporting research and development activities to facilitate acceptance of provisions that would allow for the construction of tall wood buildings in Canadian building codes and advanced wood education at engineering and architectural colleges and universities to help develop the future design capacity in Canada.
