Project contact is Thomas Miller at Oregon State University
Understanding how roof and floor systems (commonly called diaphragms by engineers) that are built from Pacific Northwest-sourced cross-laminated timber (CLT) panels perform in earthquake prone areas is a critical area of research. These building components are key to transferring normal and extreme event forces into walls and down to the foundation. The tests performed in this project will provide data on commonly used approaches to connecting CLT panels within a floor or roof space and the performance of associated screw fasteners. Structural engineers will directly benefit through improved modeling tools. A broader benefit may be increased confidence in the construction of taller wood buildings in communities at greater risk for earthquakes.
Project contact is Christopher Higgins at Oregon State University
This project will optimize the strength, stiffness, vibration characteristics, acoustic qualities and fire resistance of cross-laminated floor systems utilizing a composite concrete and cross-laminated timber product. This project includes development, testing and optimization of an economical shear connector (to connect the CLT panel to the concrete slab) that will be compared with existing screw and steel plate solutions. The resulting prototype floor system will be tested at full scale.
In many mass timber buildings, CLT or nail laminated timber (NLT) floors are designed with a concrete topping to improve acoustic separation, reduce vibration or act as a fire barrier. Little research has examined the fire behavior of these floor systems, but some preliminary tests involving LVL show that they may be able to meet three-hour fire resistance ratings, which could potentially open up the use of mass timber in Type I buildings, representing a large market opportunity. This project will test the behavior of composite floors under fire loading conditions considering the following parameters: shear connector type, mass timber panel types and thicknesses and concrete thicknesses. It will also test and validate an innovative fire research methodology using radiant panels.
This series highlights five whole building life cycle assessments (WBLCAs) of buildings incorporating the building material known as cross-laminated timber (CLT) into some or all of their structure, using a primary cradle-to-grave system boundary. This case study series will serve as an educational resource for academics, professionals, and CLT project stakeholders. While there is some uncertainty about the best way to reduce greenhouse gas emissions from architecture and construction, using CLT and other wood building materials is one possible means to reduce the emissions associated with a building’s materials. When forests are managed sustainably, wood construction materials can contribute to climate change mitigation goals as an indefinite carbon store and as a replacement of other fossil-fuel intensive materials. WBLCA is an assessment method to estimate the environmental impacts of buildings; this series offers insight into the current possibilities and limitations of WBLCA for CLT buildings. The series begins with background information on WBLCA methods and CLT, a review of previously published CLT building WBLCAs, and a life cycle assessment of an individual CLT wall element using the WBLCA softwares Tally® and Athena Impact Estimator for Buildings (Athena IE).
Project contact is Arijit Sinha at Oregon State University
Constructing buildings with CLT requires development of novel panel attachment methods and mechanisms. Architects and engineers need to know the engineering strength properties of connected panels, especially in an earthquake prone area. This project will improve knowledge of three types of wall panel connections: wall-to-floor, wall-to-wall, and wall-to-foundation. Testing will determine the strength properties of metal connectors applied with diffferent types and sizes of screw fasteners. The data will be used to develop a modeling tool that engineers can use when designing multi-story buildings to be constructed with CLT panels.
Project contact is Mariapaola Riggio at Oregon State University
Earthquake engineers are focusing on performance-based design solutions that minimize damage, downtime, and dollars spent on repairs by designing buildings that have no residual drift or “leaning” after an event. The development of timber post-tensioned (PT), self-centering rocking shear walls addresses this high-performance demand. The system works by inserting unbonded steel rods or tendons into timber elements that are prestressed to provide a compressive force on the timber, which will pull the structure back into place after a strong horizontal action. But, because these systems are less than fifteen years old with just four real-world applications, little information is known regarding best practices and optimal methods for engineering design, construction and/or tensioning procedures, and long-term maintenance considerations. This project intends to contribute knowledge by testing both cross-laminated timber (CLT) and mass plywood panel (MPP) walls through testing of anchorage detailing, investigating tensioning procedures for construction, determining the contributions of creep on prestress loss over time, and comparing all laboratory test data to monitoring data from three of the four buildings in which this technology has been implemented, one of which is George W. Peavy Hall at Oregon State University. This will be accomplished by testing small- and full-scale specimens in the A.A. “Red” Emmerson Advanced Wood Products Laboratory, and small-scale specimens in an environmental chamber.
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.
This project aims to develop a commercially-viable wood adhesive for CLT that is free of formaldehyde and isocyanates and possesses good cure speed properties. Li and his team have successfully developed adhesives for plywood manufacturing using abundant, inexpensive and renewable soy flour. This adhesive mimics the superior bonding properties of mussel additive proteins. Emission of hazardous air pollutants from plywood plants that use this adhesive has dropped 50-90 percent. Development of such an adhesive for CLT would address increasingly stringent air quality regulations in many places such as Oregon and California. The existing chemical formulation for the plywood adhesive will be adapted for use in a cold-pressing process. Specimens will be created at the OSU wood composites labs and first tested to verify conformance with the PRG320 product standard for CLT. Specimens passing the tests will be sent to the Energy Studies in Buildings Laboratory at the University of Oregon, Portland, where they will be conditioned and tested to determine emission characteristics.
The City of Springfield, Oregon hired SRG Partnership to design a CLT parking structure slated to be built in a new redevelopment zone on the Willamette River. The concept started as an academic exercise in a University of Oregon architectural design studio course led by Professor Judith Sheine. Mayor Christine Lundberg saw an opportunity to connect Springfield’s historic roots in the timber industry to the burgeoning new mass timber sector, and the project became a reality. Before the structure is built, important technical questions must be addressed concerning how to protect the timber elements against the Pacific Northwest weather and long-term dynamic loading from vehicles. A technical team from OSU’s Department of Wood Science and Engineering and School of Civil and Construction Engineering are narrowing down combinations of materials for testing. Proposed solutions include an asphalt topping on the CLT decking, similar to those often used on timber bridge decks. Stress tests will be conducted, simulating forces from vehicles turning, starting and stopping and backing up. Simulated weather testing will also be conducted in OSU’s multi-chamber modular environmental conditioning chamber. The Energy Studies in Buildings Laboratory at University of Oregon has conducted wind-driven rain studies to inform SRG’s design of the roof and exterior screening elements.
Project contact is Lech Muszynski at Oregon State University
The aim of this project is to remove this vulnerability by thoughtful conceptualization of basic strategies for optimizing the design of mass timber buildings for successful post-use material recovery/reuse and end-of-life climate benefit. Research questions will include:
1. Is demolition of decommissioned mass timber buildings a viable end-of-life option at all?
2. Can deconstruction be conducted by following construction steps in reverse order?
3.What may be the extent of damage inflicted to the connection nests, connected edges and surfaces of MTP elements during a deconstruction?
4.Can original connection nests be safely reused in structures re-using deconstructed MTP elements?
5.What is the impact of techniques and technologies selected at the design, production, and construction stages on the EOL options and carbon cost of deconstruction,
6. What is the carbon impact of deconstruction on reuse or recycling of MTP elements?
7. Do the existing deconstruction companies in the Pacific northwest have capacity to process mass timber panels that could not be reused?
8. What is the carbon costs of transportation and repurposing/recycling of MTP elements for non-structural uses?