This report is published as an addendum to NRC Research Report RR-335 “Apparent Sound Insulation in Cross-Laminated Timber Buildings." It is intended that this addendum will be merged with RR-335 in the future as a report for predicting the sound insulation in buildings using mass-timber constructions including NLT assemblies. This report presents the results from experimental studies of airborne sound transmission through assemblies of nail-laminated timber (NLT) with various linings. To put the data presented in this report in the proper context, this report begins with a brief explanation of calculation procedures to predict the apparent sound transmission class (ASTC) between adjacent spaces in a building whose structure is a combination of mass-timber assemblies such as nail-laminated timber (NLT) or cross-laminated timber (CLT) panels.
This paper presents an integrated design tool for structures composed of engineered timber panels that are connected by traditional wood joints. Recent advances in computational architecture have permitted to automate the fabrication and assembly of such structures using Computer Numerical Control (CNC) machines and industrial robotic arms. While several large-scale demonstrators have been realized, most developed algorithms are closed-source or project-oriented. The lack of a general framework makes it difficult for architects, engineers and designers to effectively manipulate this innovative construction system. Therefore, this research aims at developing a holistic design tool targeting a wide range of architectural applications. Main achievements include: (1) a new data structure to deal with modular assemblies, (2) an analytical parametrization of the geometry of five timber joints, (3) a method to generate CNC toolpath while integrating fabrication constraints, and (4) a method to automatically compute robot trajectories for a given stack of timber plates.
The study laid out in this report aims to build on the lessons learned from around the globe and
in BC to promote and facilitate the deployment of BIM and DfMA in the context of mass timber
construction. The study’s objectives were to:
1. Explore BIM tools and software platforms that support collaboration and optimization of
design solutions as well as enable seamless exchange of information in the context of
DfMA of mass-timber solutions.
2. Investigate the potential impact of the use of BIM tools and software platforms on
project and team outcomes in the context of mass-timber construction.
3. Investigate how the modeling process can be streamlined to minimize waste and
optimize the DfMA process in the context of mass-timber construction.
4. Investigate the readiness of manufacturers and installer/assemblers to supply BIM data
for products and systems.
5. Propose recommendations to position the supply chain to design, manufacture and
assemble mass-timber structures.
6. Propose recommendations that identify future training requirements for BIM enabled
DfMA in the context of mass-timber construction.
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
Summary
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.
Increasing awareness of sustainable building materials has led to interest in enhancing the structural performance of engineered wood products. Wood is a sustainable, renewable material, and the increasing use of wood in construction contributes to its sustainability. Multi-layer wooden panels are one type of engineered wood product used in construction.
There are various techniques to assemble multi-layer wooden panels into prefabricated, load-bearing construction elements. Assembly techniques considered in the earliest stages of this research work were laminating, nailing, stapling, screwing, stress laminating, doweling, dovetailing, and wood welding. Cross-laminated timber (CLT) was found to offer some advantages over these other techniques.
The mechanical properties of CLT panels constructed with layers angled in an alternative configuration produced on a modified industrial CLT production line were evaluated.
The overall experimental results suggest the use of CLT panels with a ±45°-layered configuration for construction. They also motivate the use of alternatively angled layered panels for more construction design freedom, especially in areas that demand shear resistance. In addition, the design possibility that such 45°-configured CLT can carry a given load while using less material than conventional CLT suggests the potential to use such panels in a wider range of structural applications. The results of test production revealed that 45°-configured CLT can be industrially produced without using more material than is required for construction of conventional 90°-configured panels. Based on these results, CLT should be further explored as a suitable product for use in more wooden-panel construction.
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