The previous post described some earlier large-scale seismic testing programs in mass timber. Somewhere along that timeline, engineers became increasingly interested in a more nuanced approach to preparing structures for disturbances: the concept of resilient design. Structures built to the highest seismic standards aim to be resilient, able to handle the impact of an event, adapt to any changes, and recover from them [1–3].
Resilient design uses systems that are capable of dissipating external energy and minimizing residual drift without significant structural damage [4]. Damaged buildings become hazards in their own right, left unsafe or unusable after an event, and can require costly and time-consuming repairs. Resilient design that reduces the damage sustained by a structure offers benefits like increased safety for occupants, decreased repair time after an event, decreased repair cost, and sustainability in terms of material longevity [5].
Resilience is now a guiding principle in the ongoing research around the capacity of mass timber structures, particularly in seismically active regions where designing buildings with earthquakes and similar events in mind is critical [6]. Mass timber is very light for its strength, and that fact combined with its inherent tensile strength can be used to good effect [7]. Researchers are continually developing new methods to improve how buildings handle the motion and energy induced by earthquakes by finetuning both the gravity and lateral systems to include repairable and self-centering elements.
Since 2017, starting with 2-story shake table test discussed in the last post, an exciting wave of tests have opened up the possibilities in mass timber structures. The earlier tests and the breadth of previous testing on innovative connections and components assemblies helped set the stage for some of the larger scale initiatives that we’ve seen in recent years.
In 2021 – 2022, TDI’s very own Emmerson Laboratory opened with a strong showing in the form of the Emmerson Laboratory Launch Initiative – a project that saw a three-story mass timber structure built inside of Emmerson and subjected to several of the very-slow-earthquake style tests. The structure used primarily Douglas-fir (Pseudotsuga menziesii) mass plywood panels and laminated veneer lumber columns and beams. It was a novel design for a few reasons: It was the first test of mass plywood panel-based self-centering rocking walls, and it was the first the connect the repairable elements (in this case, U-shaped flexural plates) from wall panels to boundary columns instead of between wall panels [8]. It also featured phases testing rocking walls paired with buckling restrained braces, and veneer laminated timber walls with various connections [9,10].
This project utilized lateral quasi-static loading tests, where the loading is done in stages to allow the elements to regain equilibrium in-between movements. Ultimately, the researchers pushed the building out to a maximum roof drift ratio of 4%, doubling the displacement required by many design standards.
In 2023, the second round of shake table tests under the NHERI Tallwood umbrella were groundbreaking. Researchers built, and shook, a 10-story, 34m tall building – the tallest structure ever tested on a multi-directional shake table.
Both the gravity systems and lateral force resisting systems were designed to be resilient and included repairable elements. The specimen included CLT and MPP post-tensioned shear rocking walls, floors made out of CLT, VLT, nail & dowel laminated timber with plywood sheathing (NLT/ DLT), and glue laminated timber with plywood sheathing (GLT). It also included some non-structural finishing such as staircases and a partial façade. The building underwent 88 separate simulated earthquakes. At the end, the structure was still centered and had taken minimal damage, which reinforced the capabilities of this type of design [11].
Of course, the tests did not stop there. The NHERI Converging Design program, Tallwood’s successor, featured an ambitious program including both shake table testing at the same facility and a series of analyses on how mass timber can be deconstructed and reused [12]. In fact, most of the shake table specimen itself was reused – it was the first 6 stories of Tallwood’s 10-story building, repaired and reconfigured.
This time, in 2023-2024, the researchers looked more closely at the energy dissipating elements of the lateral systems [13–15]. Specifically, they tested:
The researchers found that two of these systems worked as intended, minimizing damage and residual drift in the structure [16,17]. Results from the final system are still being analyzed but seem promising.
Other types of mass timber structures have also been investigated. Just one example was in 2024, when the Composite Recycling Technology Center, alongside Washington State University and the U.S. Army Engineer Research and Development Center put a rapid deployment shelter prototype made of thermally modified coastal Western Hemlock (Tsuga heterophylla) through its paces on a triaxial shake table in Illinois [18]. This test was an interesting case using a species that is often considered underutilized.
Earthquakes are complex movements, and the loads that they put on buildings can be devastating. Action toward building seismically resilient structures is critical for protecting both lives and infrastructure, but before action can be taken, the data needs to be there. These tests, and others by researchers around the world, have provided strong evidence that mass timber can hold its own in the arena of resilient design.
[1] M. Bruneau, A. Reinhorn, Exploring the Concept of Seismic Resilience for Acute Care Facilities, Earthquake Spectra 23 (2007) 41–62. https://doi.org/10.1193/1.2431396.
[2] M.D. Joyner, C. Gardner, B. Puentes, M. Sasani, Resilience-Based seismic design of buildings through multiobjective optimization, Engineering Structures 246 (2021) 113024. https://doi.org/10.1016/j.engstruct.2021.113024.
[3] M.H. Kurth, J.M. Keenan, M. Sasani, I. Linkov, Defining resilience for the US building industry, Building Research & Information 47 (2019) 480–492. https://doi.org/10.1080/09613218.2018.1452489.
[4] N.B. Chancellor, M.R. Eatherton, D.A. Roke, T. Akbaş, Self-Centering Seismic Lateral Force Resisting Systems: High Performance Structures for the City of Tomorrow, Buildings 4 (2014) 520–548. https://doi.org/10.3390/buildings4030520.
[5] Y. Zhang, J.F. Fung, D. Cook, K.J. Johnson, S. Sattar, Benefit–Cost Analysis for Earthquake-Resilient Building Design and Retrofit: State of the Art and Future Research Needs, Nat. Hazards Rev. 25 (2024) 03124001. https://doi.org/10.1061/NHREFO.NHENG-1910.
[6] PNW Earthquake Sources Overview, Pacific Northwest Seismic Network (n.d.). https://pnsn.org/outreach/earthquakesources (accessed August 27, 2025).
[7] Q. Wang, Z. Wang, X. Feng, Y. Zhao, Z. Li, Mechanical properties and probabilistic models of wood and engineered wood products: A review of green construction materials, Case Studies in Construction Materials 21 (2024) e03796. https://doi.org/10.1016/j.cscm.2024.e03796.
[8] P.A. Uarac, T.X. Ho, A.R. Barbosa, B. Simpson, A. Sinha, Design and cyclic testing of a full-scale three-story mass timber structure with post-tensioned self-centering rocking walls, Journal of Building Engineering 115 (2025) 114505. https://doi.org/10.1016/j.jobe.2025.114505.
[9] G.A. Araújo R., B.G. Simpson, A.R. Barbosa, L. Pieroni, T.X. Ho, G.F. Orozco O, B.T. Miyamoto, A. Sinha, Experimental and Numerical Simulation of a Three-Story Mass Timber Building with a Pivoting Wall and Buckling-Restrained Boundary Elements, Journal of Structural Engineering 151 (2025) 04025089. https://doi.org/10.1061/JSENDH.STENG-13781.
[10] N.T. Thielsen, Design and Experimental Testing of a Coupled Veneer Laminated Timber Self-Centering Rocking Wall with U-Shaped Flexural Plate Dissipators, Masters, Oregon State University, 2024. https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/d217qz885.
[11] S. Pei, K.L. Ryan, J.W. Berman, J.W. van de Lindt, S. Pryor, D. Huang, S. Wichman, A. Busch, W. Roser, S.L. Wynn, Y. Ji, T. Hutchinson, S. Sorosh, R.B. Zimmerman, J. Dolan, Shake-Table Testing of a Full-Scale 10-Story Resilient Mass Timber Building, Journal of Structural Engineering 150 (2024) 04024183. https://doi.org/10.1061/JSENDH.STENG-13752.
[12] A.R. Barbosa, NHERI Converging Design: Overview of 6-story shake-table test program, (2024).
[13] P.A. Uarac, A.R. Barbosa, A. Sinha, J.W. van de Lindt, B.G. Simpson, K. Lotfizadeh, System Identification of a Full-Scale Six-Story Building with Self-centering Rocking Walls with Distributed Energy Dissipation, in: Á. Cunha, E. Caetano (Eds.), Experimental Vibration Analysis for Civil Engineering Structures, Springer Nature Switzerland, Cham, 2025: pp. 622–631. https://doi.org/10.1007/978-3-031-96114-4_64.
[14] T.J. Field, A.R. Barbosa, A. Sinha, S. Pryor, J.W.V.D. Lindt, B. Simpson, P.A.U. P., P. Mishra, S. Kontra, M. McBain, Full-Scale Shake Table Test of Resilient Six-Story Hybrid Mass Timber and Steel Structure, in: World Conference on Timber Engineering 2025, Brisbane, Australia, 2025: pp. 2473–2480. https://doi.org/10.52202/080513-0301.
[15] M. McBain, L. Pieroni, G.A.A. R., B.G. Simpson, A.R. Barbosa, J.W.V.D. Lindt, A. Sinha, S. Kontra, P. Mishra, S. Pryor, P.A.U. P., T.J. Field, Response of Mass Ply Panel, Self-Centering Rocking Walls with Buckling Restrained Boundary Elements as Energy Dissipators in Shake Table Testing, in: World Conference on Timber Engineering 2025, Brisbane, Australia, 2025: pp. 2463–2472. https://doi.org/10.52202/080513-0300.
[16] M. McBain, L. Pieroni, G.A. Araújo Rodríguez, S. Kontra, P. Mishra, A.R. Barbosa, L. Gioiella, J.W. Van De Lindt, A. Sinha, N. Brown, F. Freddi, B.G. Simpson, Design and Shake-Table Testing of a Full-Scale, Six-Story Mass Timber Building with Posttensioned Rocking Walls and Buckling-Restrained Boundary Elements, J. Struct. Eng. 152 (2026) 04026126. https://doi.org/10.1061/JSENDH.STENG-15854.
[17] T. Field, A.R. Barbosa, S. Pryor, Simpson, Barbara, P. Uarac, A. Sinha, J.W. Van De Lindt, Shake-Table Testing of a Full-Scale Six-Story Resilient Mass Timber–Steel Hybrid Building, Journal of Structural Engineering 151 (2025) 04025210. https://doi.org/10.1061/JSENDH.%20STENG-15036.
[18] P. Bahmani, Full-Scale Shake Table Testing of a Hybrid CLT/Steel Modular Building, Washington State University, 2026.
Degenkolb's structural engineering practice reflects more than eight decades of commitment to technical expertise, exceptional client service through close collaboration, and life-long learning. Degenkolb pioneers innovative structural system designs to support the needs of our clients, including mass timber projects as engineer-of-record, peer reviewer, and in construction engineering.
DLR Group is an integrated design firm delivering architecture, engineering, interiors, planning, and building optimization for new construction, renovation, and adaptive reuse. Our promise is to elevate the human experience through design. This promise inspires sustainable design for a diverse group of public and private sector clients; local communities; and our planet. DLR Group is 100 percent employee-owned and fully supports the initiatives and goals of the 2030 Challenge, and is an initial signatory to the China Accord and the AIA 2030 Commitment.
FFA has recently created 20 projects utilizing mass timber. For our team this is a design and research opportunity, leveraging post-occupancy evaluation, performance tracking, and material sourcing studies to continuously refine its approach. The dedication to using high-tech wood products for small and large projects helps us connect to our region through a range of attributes from aesthetics to economic solutions. This endeavor brings together multiple experts from across the research, design, and construction industry together creating better solutions for the community we serve.
Forell | Elsesser (F|E) is an award-winning structural engineering firm known for innovative design solutions that are practical and scalable. The firm brings deep expertise in mass timber design, with particular strength in vibration mitigation and performance-based seismic engineering for complex buildings. An active collaborator with academic partners and industry stakeholders, F|E contributes targeted research insights that help close knowledge gaps and support broader adoption of mass timber solutions.
Holmes is an international engineering firm specializing in advanced structural and fire engineering across the Pacific Rim. With deep expertise spanning research, design, and construction, Holmes has contributed to industry-advancing initiatives including collaborative research with academia, development of industry design guides and participation on multiple code advancement committees. This expertise extents particularly to mass timber, where Holmes has been involved in some of the largest and most innovative mass timber buildings in North America, New Zealand, Australia and beyond.
Kalesnikoff Mass Timber is a vertically integrated manufacturer specializing in mass timber (CLT, GLT, Glulam), prefabricated wall systems and fully volumetric modular construction. Through in-house R&D and advanced manufacturing, we optimize structural systems and detailing to improve constructability, performance, and code compliance across a wide range of building types.
KPFF is a nationally recognized structural and civil engineering firm with over 1,500 employees. We have contributed to the U.S. mass timber movement since its infancy in the Pacific Northwest and have helped expand its reach across the entire United States. We are especially passionate about translating mass timber research into practice including point-supported cross-laminated timber (CLT), post-tensioned timber rocking walls, mass timber floor vibration, CLT diaphragms, timber braced frames, fire and acoustic testing, large-scale shake-table testing, and many other research and development topics.
LEVER is a leading architectural practice based in Portland, Oregon and Los Angeles recognized for design excellence that combines purpose, craft and material innovation LEVER has pioneered mass timber firsts for over a decade, with projects that are catalysts for connecting sustainable urban development to rural economic growth regionally and nationally. The company’s office, Albina Yard, was the first building in the United States to use domestically sourced CLT and their Framework project was the first wood high-rise design in the United States to receive approval for construction. LEVER has designed over 20 mass timber projects focusing on leveraging the specific qualities of a place—climate, access to materials, community, and the resources of the specific sites of their work.
Mithun is a 75-year-old design firm with offices in Seattle, San Francisco and Los Angeles. The firm’s interdisciplinary team has been working with mass timber since 2017 on diverse projects spanning commercial office, cultural, industrial and education markets. As part of the Mithun R+D program, the firm has advanced mass timber knowledge and application through self-funded research like the Building Better Schools mass timber kit of parts system that has informed multiple K-12 projects at Mithun and been widely referenced by other institutions and firms in their efforts to design economical mass timber schools. Mithun also actively participates in industry-led research such as its successful execution of two NFPA 285 fire tests on CLT walls through the USDA Wood Innovations Grant program, acoustic testing in multifamily CLT floor assemblies, and a current research project with WSU and NRRI to develop a thermally modified strand-based CLT panel for commercial use.
Rothoblaas delivers practical, high-performance solutions for mass timber and wood construction, from structural fasteners and connection systems to membranes and safety products. Supported by internal testing, technical documentation, and engineering resources, Rothoblaas helps architects, engineers, and builders navigate U.S. code requirements with strong technical support and R&D driven guidance. Through education and collaboration, we help move mass timber projects from design to jobsite with confidence.
Degenkolb's structural engineering practice reflects more than eight decades of commitment to technical expertise, exceptional client service through close collaboration, and life-long learning. Degenkolb pioneers innovative structural system designs to support the needs of our clients, including mass timber projects as engineer-of-record, peer reviewer, and in construction engineering.
StructureCraft is an industry leader in the design, engineering, and fabrication of advanced mass timber and hybrid timber systems, with a strong focus on innovation and constructability. The company has extensive experience delivering complex timber structures globally. With deep expertise in digital fabrication and in-house R&D, StructureCraft collaborates closely with architects and researchers to push the boundaries of sustainable, low-carbon construction, bringing unique technical strength and practical insight to the REACTS group.
WSP is one of the world’s leading professional services firms, uniting engineering, advisory, and science-based expertise to shape communities. Within this global network, our structural engineering teams are recognized for innovative approaches to complex building systems. We apply advanced design strategies for mass timber and hybrid structures, combining sustainability with technical precision. Through ongoing research and development, we create resilient, future-ready solutions that redefine what’s possible in the built environment.
Freres Engineered Wood is a premier wood products manufacturing company dedicated to bringing innovative, high-quality and environmentally-sound wood products to market. Founded in 1922, Freres is one of the oldest family-owned and operated businesses in Oregon, and values the personal relationships it has developed with customers and partners over the years.
Hilti stands for innovation and direct customer relationships. Based in Schaan, Liechtenstein, Hilti has about 34,000 employees around the world in more than 120 countries. Hilti provides the construction industry with advanced hardware, software, and services to make customers work more productive, safer, and more sustainable. Hilti also invests approximately 6 percent of sales each year in research and development to develop new cutting-edge solution for the customers. From product development to manufacturing, logistics, sales, and services, Hilti covers the entire value-added chain. Overall, Hilti aims to be the best partner of the customers in making construction better.
