This Week in Structural Engineering: Mass Timber Milestones, Recycled Plastic Trusses, and the Future of Bridge Repair
April 2026 brings a concentration of structural engineering developments that collectively illustrate how rapidly the profession is evolving. From a conference floor in Portland to a research lab at MIT, and from the towers of the Golden Gate Bridge to a demonstration site in Massachusetts, the work being done right now is redefining what structural engineers can design, build, and repair.
Here is what you need to know.
MIT Prints Construction-Grade Floor Trusses from Recycled Plastic
Researchers at MIT have 3D printed structural floor trusses using a composite of recycled polyethylene terephthalate (rPET) mixed with glass fibers. The results, published in the Solid FreeForm Fabrication Symposium Proceedings, are striking.
Each 8-foot-long truss was printed in approximately 13 minutes. The trusses weigh just 13 pounds each, lighter than comparable wooden members. And in load testing, the printed flooring system supported over 4,000 pounds, exceeding standards set by the U.S. Department of Housing and Urban Development.
The MIT HAUS team, operating within the Laboratory for Manufacturing and Productivity, has been developing this technology since 2019. The rPET feedstock is primarily sourced from discarded drink bottles, making this a genuine circular economy application in structural construction.
For practicing structural engineers, the implications are significant. If recycled plastic composites can meet prescriptive load and deflection criteria for rdesidential floor systems, the material palette available for lightweight framing expands considerably. The 13-minute print time per truss also suggests potential for rapid deployment in disaster recovery and affordable housing scenarios.
Source: MIT News
AISC 2026 IDEAS Awards Spotlight Cold-Spray Additive Manufacturing
The American Institute of Steel Construction announced the winners of its 2026 IDEAS Awards, the steel industry’s most prestigious design recognition. Six projects were honored, but the standout is the inaugural IDEAS|next Award, which was presented not to a building but to an idea.
A research team developed a portable, field-ready cold-spray additive manufacturing system capable of repairing damaged steel bridge members. In the Great Barrington Cold Spray Demo Repair, the team digitally mapped a damaged cross section and restored it using the cold-spray process in hours rather than the days typically required for conventional repair methods.
This technology has the potential to fundamentally change how engineers approach maintenance and rehabilitation of aging steel infrastructure. Rather than replacing entire members or mobilizing heavy welding equipment, a portable cold-spray unit could restore section properties on site with minimal traffic disruption.
Other notable winners include the University of Arizona Andrew Weil Center for Integrative Medicine, recognized for Excellence in Architecture, and the San Diego International Airport renovation. The airport project achieved $100 million in savings through sustainability-optimized design and introduced a novel seismic system engineered for a 100-year service life.
Source: AISC
International Mass Timber Conference Opens Its 10th Year
The International Mass Timber Conference, the world’s largest gathering of mass timber professionals, opened today at the Oregon Convention Center in Portland for its 10th annual event. Over 190 exhibitors are participating, with attendees from more than 30 countries.
This year’s keynote lineup is notable. Kengo Kuma, whose timber-forward architectural practice has influenced designers globally, will deliver the Wednesday address. Thursday’s keynote features representatives from Amazon and Meta discussing the next decade of corporate mass timber adoption. Both companies, along with Google, Microsoft, and Under Armour, have committed to mass timber for new campus developments.
The U.S. mass timber market is growing at 20 to 30 percent annually, with projections exceeding $5.7 billion by 2030. Michigan alone has more than 65 mass timber projects complete, in development, or under construction. California’s Mad River Mass Timber has emerged as the state’s first producer of dowel-laminated timber (DLT), with technical guidance from UC Berkeley’s Wood Lab.
For structural engineers, the conference is a barometer of how quickly mass timber is moving from niche to mainstream. The involvement of Fortune 500 technology companies as end users signals that demand for engineers with CLT, glulam, and NLT expertise will only accelerate.
Source: International Mass Timber Conference
Golden Gate Bridge Seismic Retrofit Enters $1.8 Billion Final Phase
The final phase of the Golden Gate Bridge seismic retrofit program is officially underway. Backed by $1 billion in newly approved funding, the total project cost now exceeds $1.8 billion, driven in part by post-pandemic construction inflation.
The scope of work includes steel plate reinforcements to both suspension towers, truss and floor beam strengthening, and the installation of energy dissipation devices to absorb seismic shock. The work is divided into two subphases: Contract 1 spanning six years, followed by a $900 million second phase lasting five additional years.
Funding sources include a $400 million federal grant, $270 million from district reserves, and $200 million from California’s Highway Bridge Program. The retrofit program originated in 1997, eight years after the 1989 Loma Prieta earthquake revealed that a strong seismic event near the bridge could cause catastrophic structural failure.
This project represents one of the largest single-bridge rehabilitation efforts in U.S. history and will serve as a reference case for seismic retrofit methodology on iconic suspension structures for decades to come.
Source: Roads and Bridges
Holcim Demonstrates World’s First Net-Zero Concrete
Holcim, in partnership with Canary Wharf Group in London, completed a trial producing concrete with a carbon footprint of negative 14 kg of CO2 per cubic meter. The mix incorporates biochar derived from forestry residues and used coffee grounds, sequestering more carbon than is emitted during production.
This is a significant milestone. Conventional concrete production accounts for approximately 8 percent of global CO2 emissions. If net-zero (or carbon-negative) concrete can be scaled commercially, the embodied carbon equation for structural engineers changes fundamentally. Supplementary cementitious materials, alkali-activated binders, and carbon capture utilization collectively show potential to reduce cement emissions by 30 to 50 percent across the industry.
Source: Holcim UK
NIST Champlain Towers Investigation Expected to Conclude in 2026
The National Institute of Standards and Technology expects to finalize its investigation into the 2021 Champlain Towers South collapse in Surfside, Florida, this year. The collapse, which killed 98 people, prompted nationwide scrutiny of aging concrete structures, building inspection protocols, and condominium maintenance requirements. The final report is expected to include code change recommendations with broad implications for engineers conducting existing building assessments and rehabilitation design.
Source: ConstructConnect
What It All Means
The thread running through this week’s developments is convergence. Materials science, digital fabrication, artificial intelligence, and sustainability targets are converging in ways that are producing real, tested, field-ready innovations. Structural engineers who stay current with these developments will be better positioned to serve clients, win projects, and push the profession forward.
At JMVC Consulting Structural Engineers, we track these developments daily so that our designs reflect the best of what the industry has to offer. If you have a project that could benefit from innovative structural solutions, we would welcome the conversation.
This article is part of JMVC Consulting’s weekly structural engineering research series. Subscribe to receive the latest industry developments directly in your inbox.