From Recycled Plastic Trusses to the World’s Tallest Church
The structural engineering profession is advancing at a pace that would have been difficult to imagine even five years ago. This week’s developments span additive manufacturing, landmark project milestones, carbon-negative materials, and updates to critical design standards. Each of these stories carries practical implications for how we design, specify, and build.
MIT Proves Structural Framing Can Be 3D Printed from Recycled Plastic
Massachusetts Institute of Technology
MIT’s HAUS group has published research demonstrating that construction-grade framing elements can be 3D printed from a composite of recycled polyethylene terephthalate (rPET) mixed with glass fibers. The team printed four 8-foot floor trusses, each completed in approximately 13 minutes, using an industrial-scale machine capable of processing 80 pounds of material per hour.
The printed trusses supported over 4,000 pounds in load testing, exceeding key building standards established by the U.S. Department of Housing and Urban Development. What distinguishes this research from prior additive manufacturing experiments in construction is the scope of application: the MIT team is targeting not just walls or decorative elements, but the full range of structural framing, including foundation pilings, floor trusses, stair stringers, roof trusses, wall studs, and joists.
The researchers envision a closed-loop production system in which discarded plastic bottles are shredded, pelletized, and fed directly into large-scale 3D printers to produce load-bearing structural components. This approach simultaneously addresses plastic waste and the demand for affordable, rapidly deployable housing. The research was published in the Solid FreeForm Fabrication Symposium Proceedings and has been covered by Newsweek, 3D Printing Industry, and MIT News.
The Sagrada Familia Is Now the World’s Tallest Church
On February 20, 2026, the four horizontal arms of the cross atop the Tower of Jesus Christ were installed at Barcelona’s Sagrada Familia, completing the exterior of the basilica’s central tower at a height of 172.5 meters. The structure now surpasses Germany’s Ulm Minster by 11 meters to become the tallest church building in the world, bringing to a close the exterior construction of a project that broke ground 144 years ago.
The structural engineering behind this milestone, led by Arup, is worth studying in detail. The design team determined early on that towers built in traditional masonry or earthquake-resistant reinforced concrete with stone cladding would be too heavy for the existing foundations and crypt below. Their solution was a pre-compressed stone system that combines carved stone panels with internal steel reinforcement. This allowed tower elements to be prefabricated off-site and transported for level-by-level installation.
The design process itself was a hybrid of deep human expertise and computational power. A parametric approach enabled the team to model hundreds of subtle geometric variations, optimizing structural performance while remaining faithful to Gaudi’s original vision. Interior work on the basilica will continue through 2027 and 2028, as reported by Vatican News and ArchDaily.
WPI’s Enzymatic Structural Material: A Carbon-Negative Alternative to Concrete
Researchers at Worcester Polytechnic Institute, led by Professor Nima Rahbar, have developed an enzymatic structural material (ESM) that removes more carbon from the atmosphere than it produces during manufacturing. The material uses carbonic anhydrase, an enzyme found in human red blood cells, to convert atmospheric CO2 into solid mineral particles. These particles are bound together and cured under mild conditions, producing structural forms within hours.
The numbers tell a compelling story: one cubic yard of ESM stores 18 pounds of CO2, while one cubic yard of conventional concrete emits approximately 400 pounds. Unlike traditional concrete, which requires high temperatures and weeks of curing, ESM is produced rapidly and with a dramatically lower environmental footprint. The material is strong, repairable, and recyclable.
Published in the journal Matter, this research has generated significant attention for potential applications in affordable housing, climate-resilient construction, and disaster relief, where lightweight, quickly produced structural materials can accelerate rebuilding. As reported by Interesting Engineering, if adopted widely, ESM could significantly reduce emissions across the construction sector.
AISC 2026 IDEAS Awards Recognize Six Groundbreaking Steel Projects
The University of Arizona Andrew Weil Center for Integrative Medicine, Tucson, Ariz., was honored with the 2026 IDEAS Award for Excellence in Architecture. Photo: Bradley Wheeler Architectural Photography + Placement
The American Institute of Steel Construction has announced the winners of its 2026 IDEAS Awards, and several projects stand out for their structural innovation.
The City of Boulder Fire Rescue Station No. 3 in Colorado directly reuses steel members salvaged from a deconstructed local hospital, minimizing embodied carbon while designing for a 100-year service life. The structural engineering was performed by KL&A Engineers & Builders.
San Diego International Airport Terminal 1, engineered by Magnusson Klemencic Associates, employed buckling-restrained braced frames (BRBFs) for seismic resistance while maintaining ongoing airport operations. The collaborative design approach delivered approximately $100 million in cost savings.
The University of San Francisco’s Malloy Pavilion, engineered by ZFA Structural Engineers, is seismically isolated from the parking structure below and supported on just three columns using long-span perimeter trusses to house NCAA basketball and volleyball courts.
Perhaps the most forward-looking recognition went to the inaugural IDEAS “next” Award for cold spray additive manufacturing technology developed by UMass Amherst and MIT in partnership with MassDOT. This portable system enables bridge repairs to be completed in hours rather than days, as detailed by BD+C Network.
AISC 341 Seismic Provisions: Key Changes in the Upcoming 2027 Edition
A draft of the next edition of AISC 341, Seismic Provisions for Structural Steel Buildings, is available for public review ahead of its anticipated 2027 publication. The proposed changes are substantial and warrant attention from practicing structural engineers.
Key revisions include updated seismic width-to-thickness limits for braces and columns, revised design requirements for special truss moment frames, updated detailing requirements for base connections of composite plate shear wall systems, and new provisions for rod-braced diaphragms with special seismic detailing. Analysis requirements have also been revised.
A companion update to AISC 303, the Code of Standard Practice for Steel Buildings and Bridges, is also under review. Structural engineers working on seismic projects should review the draft at AISC and submit comments to inform the final standard.
Europe’s Largest 3D-Printed Residential Building and the Holcim Innovation Pipeline
ViliaSprint2 in France has earned the distinction of being Europe’s largest 3D-printed residential building. The load-bearing walls for the 800-square-meter, three-story social housing residence were printed in 34 working days using custom fiber-reinforced concrete, achieving construction speeds up to 50% faster than conventional methods.
Holcim has also advanced several material innovations worth tracking. Their net-zero concrete prototype for the Canary Wharf development in London integrates biochar into the mix, achieving a carbon footprint of negative 14 kg of CO2 per cubic meter. Separately, Holcim expects to produce 1 million tons of calcined clay by 2026, a supplementary cementitious material that can halve cement’s CO2 footprint while reducing dependence on scarce industrial by-products such as slag and fly ash. Full details are available in Holcim’s innovation report.
Burj Binghatti: Engineering the World’s Tallest Residential Tower
Dubai’s Burj Binghatti Jacob & Co Residences continues its ascent toward a projected Q2 2026 completion, targeting approximately 557 meters across 105 stories to become the world’s tallest strictly residential tower. The structural system employs high-strength concrete and steel to maintain structural integrity while minimizing weight, a critical factor given the tower’s slender profile.
Managing occupant comfort at extreme heights requires sophisticated wind engineering solutions. The ornate diamond-shaped crystal crown at the pinnacle, while architecturally striking, introduces additional aerodynamic complexity. High-performance glass curtain walls serve dual structural and thermal functions, reducing solar heat gain in a climate where summer temperatures regularly exceed 40 degrees Celsius. Further technical details are available at Parametric Architecture and Interesting Engineering.
What to Watch This Week
The convergence of additive manufacturing, carbon-negative materials, and parametric design tools is reshaping what structural engineers can achieve. Whether it is printing load-bearing trusses from waste plastic, completing a 144-year cathedral with algorithmic precision, or repairing bridges in hours with cold spray technology, these developments signal a profession in rapid evolution. Stay informed, engage with the public review of AISC 341, and consider how these innovations might apply to your current projects.