Mass timber products are growing in popularity, particularly in multifamily residential dwellings, for which they are structurally well-suited. However, acoustic performance of these products has not been robustly tested, which can be a hindrance to building projects due to lack of code compliance or building performance with poor acoustics. The latter is particularly important since the sound transmission class (STC) rating—a single number used to characterize decibel attenuation—does not characterize an assembly in terms of which frequencies it blocks well or transmits. Wood does a good job of attenuating mid- to high-range frequencies, but not necessarily low ones, such as from a sub-woofer, so testing of assemblies is critical because it elicits their performance in terms of the entire range of frequencies, in addition to defining a single STC rating. This allows for adjustments to be made that balance the acoustic performance of the assembly – such as adding isolation through solutions like air space or concrete topping – with construction cost, sequencing and aesthetics. The other standard acoustic rating, impact insulation class (IIC), accounts for foot-fall and other impact noises and is another critical test for determining code compliance of floor assemblies.
The increasing appetite for innovation, performance and sustainability in the Canadian Architecture, Engineering, Construction, Owners and Operators (AECOO) community is leading to the development and deployment of approaches, be they tools, technologies, practices, etc., that are causing a significant shift in the delivery and management of built assets. When deployed...
Our built environment is constantly adapting to changing factors: technology, the state of the economy, material resource availability, and, in turn, environmental conditions. The latter has gained notable importance in popular discourse, and especially in the architecture and construction professions. However, as much as we see terms such as “sustainability” and “green” in our everyday lives, government and industry are slow to take action investing in our future environment. Material resources in the building industry are worth investigating. Timber, used as a structural material to compete with concrete and steel, brings more energy efficient and natural renewable resources to our growing cities. In order to provide a broader perspective of how we as a society use concrete, steel, and timber, I will compare the three building materials in a four part guideline: Environmental Performance, Ease of Manufacture, Organized Assembly, and Design Flexibility.
Project contact is Mark Fretz at the University of Oregon
University of Oregon and Oregon State University are collaborating through TallWood Design Institute (TDI) to upgrade aging, energy inefficient and seismically unprepared multifamily housing by developing a mass plywood (MPP) retrofit panel assembly that employs digital workflows and small diameter logs (down to 5") to create an economically viable energy/seismic retrofit model for the West Coast and beyond. The project has broad potential to support forested federal land management agencies and private forestry by proving a new market for small diameter logs.
Traditional wood-wood connections, widely used in the past, have been progressively replaced by steel fasteners and bonding processes in modern timber constructions. However, the emergence of digital fabrication and innovative engineered timber products have offered new design possibilities for wood-wood connections. The design-to-production workflow has evolved considerably over the last few decades, such that a large number of connections with various geometries can now be easily produced. These connections have become a cost-competitive alternative for the edgewise connection of thin timber panels. Several challenges remain in order to broaden the use of this specific joining technique into common timber construction practice: (1) prove the applicability at the building scale, (2) propose a standardized construction system, (3) develop a convenient calculation model for practice, and (4) investigate the mechanical behavior of wood-wood connections. The first building implementation of digitally produced through-tenon connections for a folded-plate structure is presented in this work. Specific computational tools for the design and manufacture of more than 300 different plates were efficiently applied in a multi-stakeholder project environment. Cross-laminated timber panels were investigated for the first time, and the potential of such connections was demonstrated for different engineered timber products. Moreover, this work demonstrated the feasibility of this construction system at the building scale. For a more resilient and locally distributed construction process, a standardized system using through-tenon connections and commonly available small panels was developed to reconstitute basic housing components. Based on a case-study with industry partners, the fabrication and assembly processes were validated with prototypes made of oriented strand board. Their structural performance was investigated by means of a numerical model and a comparison with glued and nailed assemblies. The results showed that through-tenon connections are a viable alternative to commonly used mechanical fasteners. So far, the structural analysis of such construction systems has been mainly achieved with complex finite element models, not in line with the simplicity of basic housing elements. A convenient calculation model for practice, which can capture the semi-rigid behavior of the connections and predict the effective bending stiffness, was thus introduced and subjected to large-scale bending tests. The proposed model was in good agreement with the experimental results, highlighting the importance of the connection behavior. The in-plane behavior of through-tenon connections for several timber panel materials was characterized through an experimental campaign to determine the load-carrying capacity and slip modulus required for calculation models. Based on the test results, existing guidelines were evaluated to safely apply these connections in structural elements while a finite element model was developed to approximate their performance. This work constitutes a firm basis for the optimization of design guidelines and the creation of an extensive database on digitally produced wood-wood connections. Finally, this thesis provides a convenient design framework for the newly developed standardized timber construction system and a solid foundation for research into digitally produced wood-wood connections.
A. Fire Test Results Summary
B. Test 1a (Test 1): Beam-Exterior Column Connection Report
C. Test 1a (Test 2): Beam-Exterior Column Connection Report
D. Test 1a (Test 3): Beam-Exterior Column Connection Report
E. Test 1a (Test 4): Beam-Exterior Column Connection Report
F. Test 1b (Test 1): CLT Deck to Beam Report
G. Test 1b (Test 2): CLT Deck to Beam Report
H. Test 1b (Test 3): CLT Deck to Beam Report
I. Test 1c: Penetrations Fire Resistance Rating Report (TBD)
J. Test 1d: Wall Fire Resistance Rating Report
Sound insulation performance is critical to the broader market acceptance of mass timber buildings in both residential and non-residential building markets. The project aims to develop dry floating floor solutions for mass timber floors with improved sound insulation performance. The specific objectives are:
1. To design floating floor assemblies using wood-based panels such as medium density fiberboard (MDF), gypsum board, and structural concrete panels for mass timber floors with considerations for fire requirements;
2. To evaluate the impact sound insulation performance of developed floor assemblies with a focus in the low-frequency range.