Project contact is Erol Karacabeyli at FPInnovations
Summary
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.
Ease of construction and favorable overall costs relative to other construction types are making high-rise (i.e., 4- and 5-story) wood frame construction increasingly popular. With these buildings increasing in height, there is a greater impetus on designers to address frame and finishes movement in such construction. As we all know, buildings are dynamic creatures experiencing a variety of movements during construction and over their service life. In wood frame construction, it is important to consider not only absolute movement but also differential movement between dissimilar materials.
This article focuses on differential movement issues and how to recognize their potential and avoid problems by effective detailing.
In wood-frame buildings of three or more stories, cumulative shrinkage can be significant and have an impact on the function and performance of finishes, openings, mechanical/electrical/plumbing (MEP) systems, and structural connections. However, as more designers look to wood-frame construction to improve the cost and sustainability of their mid-rise projects, many have learned that accommodating wood shrinkage is actually very straightforward. This publication will describe procedures for estimating wood shrinkage and provide detailing options that minimize its effects on building performance.
In this paper a precise model is established for deflection prediction of mechanically jointed beams with partial composite action. High accuracy of the proposed method is demonstrated through comparison with a comprehensive finite element (FE) modelling for a timber-concrete partial composite beam. Next, the obtained numerical results are compared with gamma-method, a well-known simplified solution for timber engineers according to the Eurocode 5. Validity and accuracy level of the gamma-method are investigated for various boundary conditions as well as different values of beam length-to-depth ratio, and discussed in details.
Project contact is Peter Dusicka at Portland State University
Summary
The urgency in increasing growth in densely populated urban areas, reducing the carbon footprint of new buildings, and targeting rapid return to occupancy following disastrous earthquakes has created a need to reexamine the structural systems of mid- to high-rise buildings. To address these sustainability and seismic resiliency needs, the objective of this research is to enable an all-timber material system in a way that will include architectural as well as structural considerations. Utilization of mass timber is societally important in providing buildings that store, instead of generate, carbon and increase the economic opportunity for depressed timber-producing regions of the country. This research will focus on buildings with core walls because those building types are some of the most common for contemporary urban mid- to high-rise construction. The open floor layout will allow for commercial and mixed-use occupancies, but also will contain significant technical knowledge gaps hindering their implementation with mass timber. The research plan has been formulated to fill these gaps by: (1) developing suitable mid- to high-rise archetypes with input from multiple stakeholders, (2) conducting parametric system-level seismic performance investigations, (3) developing new critical components, (4) validating the performance with large-scale experimentation, and (5) bridging the industry information gaps by incorporating teaching modules within an existing educational and outreach framework. Situated in the heart of a timber-producing region, the multi-disciplinary team will utilize the local design professional community with timber experience and Portland State University's recently implemented Green Building Scholars program to deliver technical outcomes that directly impact the surrounding environment.
Research outcomes will advance knowledge at the system performance level as well as at the critical component level. The investigated building system will incorporate cross laminated timber cores, floors, and glulam structural members. Using mass timber will present challenges in effectively achieving the goal of desirable seismic performance, especially seismic resiliency. These challenges will be addressed at the system level by a unique combination of core rocking combined with beam and floor interaction to achieve non-linear elastic behavior. This system behavior will eliminate the need for post-tensioning to achieve re-centering, but will introduce new parameters that can directly influence the lateral behavior. This research will study the effects of these parameters on the overall building behavior and will develop a methodology in which designers could use these parameters to strategically control the building seismic response. These key parameters will be investigated using parametric numerical analyses as well as large-scale, sub-system experimentation. One of the critical components of the system will be the hold-down, a device that connects the timber core to the foundation and provides hysteretic energy dissipation. Strength requirements and deformation demands in mid- to high-rise buildings, along with integration with mass timber, will necessitate the advancement of knowledge in developing this low-damage component. The investigated hold-down will have large deformation capability with readily replaceable parts. Moreover, the hold-down will have the potential to reduce strength of the component in a controlled and repeatable way at large deformations, while maintaining original strength at low deformations. This component characteristic can reduce the overall system overstrength, which in turn will have beneficial economic implications. Reducing the carbon footprint of new construction, linking rural and urban economies, and increasing the longevity of buildings in seismic zones are all goals that this mass timber research will advance and will be critical to the sustainable development of cities moving forward.
The growing diffusion of cross-laminated timber structures (CLT) has been accompanied by extensive research on the peculiar characteristics of this construction system, mainly concerning its economic and environmental benefits, lifecycle, structural design, resistance to seismic actions, fire protection, and energy efficiency. Nevertheless, some aspects have not yet been fully analysed. These include both the knowledge of noise protection that CLT systems are able to offer in relation to the possible applications and combinations of building elements, and the definition of calculation methods necessary to support the acoustic design. This review focuses on the main acoustic features of CLT systems and investigate on the results of the most relevant research aimed to provide key information on the application of acoustic modelling in CLT buildings. The vibro-acoustic behaviour of the basic component of this system and their interaction through the joints has been addressed, as well as the possible ways to manage acoustic information for calculation accuracy improvement by calibration with data from on-site measurements during the construction phase. This study further suggests the opportunity to improve measurement standards with specific reference curves for the bare CLT building elements, in order to compare different acoustic linings and assemblies on the same base. In addition, this study allows to identify some topics in the literature that are not yet fully clarified, providing some insights on possible future developments in research and for the optimization of these products.
This report summarizes the acoustics research component regarding sound insulation of elements and systems for the research project on mid-rise and larger wood buildings. The summary outlines the background, main research considerations, research conducted and major outcomes. Further details of the design and the results can found in the appendix of Client Report A1-100035-02.1 [1].
The goal of the acoustics research components was to develop design solutions for mid-rise wood and wood-hybrid buildings that comply both with the current National Building Code of Canada (NBCC) 2010 [2] requirements for direct sound insulation and with the anticipated requirements for flanking sound transmission in the proposed, 2015 version of the NBCC. In addition, the design solutions were to provide better impact sound insulation while still achieving code compliance for all other disciplines (interdependencies) as identified in the final report of the scoping study conducted in FY 2010/2011 [3]
The following topics in the field of seismic analysis and design of mid-rise (5- and 6-storey) wood-frame buildings are included in this paper: Determination of the building period, linear dynamic analysis of wood-frame structures, deflections of stacked multi-storey shearwalls, diaphragm classification, capacity-based design for woodframe...
Airborne sound insulation performance of wall assemblies is a critical aspect which is directly associated with the comfort level of the occupants, which in turn affects the market acceptance. In single-family and low-rise residential buildings, the partition walls, whether loadbearing or non-loadbearing, are commonly framed with studs of solid sawn lumber of 2x4, 2x6, and 2x8. In commercial buildings and multi-storey residential buildings, the partition walls are commonly framed using light-gauge steel studs.
The shortcomings of solid sawn lumber studs form the motivation for this project to develop wood studs that would address these shortcomings to promote greater wood use in partition walls.
The conceptual design and fabrication work and the preliminary test results have shown that are partition-wall stud made out of composite wood material could have the same or better airborne sound insulation performance as compared to the 25 gauge steel stud. The concept is promising, with a manufacturing process and fabrication that would work and be practical.
Lack of research and design information for the seismic performance of balloon-type CLT shear walls prevents CLT from being used as an acceptable solution to resist seismic loads in balloon-type mass-timber buildings. To quantify the performance of balloon-type CLT structures subjected to lateral loads and create the research background for future code implementation of balloon-type CLT systems in CSA O86 and NBCC, FPInnovations initiated a project to determine the behaviour of balloon-type CLT construction. A series of tests on balloon-type CLT walls and connections used in these walls were conducted. Analytical models were developed based on engineering principles and basic mechanics to predict the deflection and resistance of the balloon-type CLT shear walls. This report covers the work related to development of the analytical models and the tests on balloon-type CLT walls that the models were verified against.
