Modern Steel Construction • December 2023 • What’s Cool in Steel

Every year, Modern Steel Construction compiles several captivating developments that showcase structural steel’s versatility.

This year’s list features multiple projects, including a downtown Chicago office building constructed in tight quarters and a steel sculpture that greets airport visitors to Dallas. Going beyond projects, read about an emerging fabrication trend, one general contractor’s way of helping address the trade labor shortage, a steel artist, and more.

Steel Takes Off

SCULPTOR ED CARPENTER’S fourth project with AISC member fabricator Puritan Manufacturing, Inc. is a guardian of sorts for Dallas’ Love Field Airport.

LoveBird, a 90-ft wingspan steel structure, sits at the airport’s main entrance—immediately next to the end of a runway.

“Poised for flight, LoveBird alights at the head of the runway, spreading its wingspan in a display of pride and optimism,” Carpenter wrote in his description. “Its sleek contours complement the modernism of the terminal, suggesting a fantastical bird or advanced aircraft.

“To some, it may evoke the wing display of the mockingbird, the name of the adjacent roadway and Texas’ state bird. Is it ascending or descending? Either way, it rises delicately from a fine point, slightly canted, stabilized only by slender cables arrayed in a fan form suggesting tail feathers.”

The sculpture’s position at the head of the runway meant it could not exceed the FAA’s 20-ft height limit. But Carpenter felt the site demanded a bold statement, and his solution was to expand LoveBird’s wings as far as possible. His design called for a 20 ft high by 90 ft wide structure evoking something landing or taking off and meeting the ground slightly angled on a base only 2½ in. wide. It was completed in October 2021 and is among the most recent projects by Carpenter, who specializes in monumental public art and is based in Portland, Ore.

Carpenter chose Puritan—based in Omaha, Neb. —to fabricate the steel for LoveBird. Puritan normally provides structural steel fabrication, platforms, stairs, and other goods for industrial-based companies. It had, though, worked with Carpenter three previous times, beginning in 2010 when the Iowa West Foundation commissioned him to provide a sculpture on a viaduct in Council Bluffs, Iowa. Puritan also fabricated his 55,000-lb. stainless steel sculpture in Lincoln, Neb., called “Harvest” and the 70-ft “Micro Macro Mojo” in Richardson, Texas, which combines stainless and hot-dip galvanized steel.

“Each of these four projects has a different challenge in rendering an artist’s vision into physical reality,” Puritan president and general manager Dave Waters said.

With LoveBird, the geometry was symmetrical, but the sculpture had to be positioned at a slight compounded offset to give the illusion that the object was flying or nearly weightless.

The structure is fabricated from 304 stainless steel and was painted bright red. Perhaps the most unusual aspect is that all 10,000 lb of the stainless steel sit on a ¼ in. thick donut with a 2½ in. o.d. and a 1¾ in. i.d. It required a donut-shaped base because the electrical wires for the lights needed to come from a conduit below. Combined with the weight and deflection of the cantilevered wings spreading out from the center main structure, Puritan thoroughly deliberated a plan for something that would be within the budget but still durable and functional. Aluminum was even discussed as an option, but 304 stainless steel won out for its strength, durability, and lifespan.

Structural angle was used for the wing frames, with lasercut 3⁄8 in. thick baffle connections and all-welded construction. The wing panels needed to be removable for erection and light maintenance requirements. Most useful in assembly was the RIVNUT fastening system, which alleviated the need for 3,500 ¼ in.-20 UNC fasteners to attach the wing panels to the stainless steel structure.

“We didn’t want to weld threaded nuts to the structure 3,500 times,” Waters said.

All components were laser cut on a Trumpf fiber, 6KW, L3040, and the structural stainless steel was produced on a Peddinghaus Q643 Anglemaster, which provided enough accuracy to locate the fasteners.

The six wings on LoveBird are almost identical. The overall structure is broken into six components:

The main base structure needed to support all the weight concentrated to this one point. Puritan used ¼ in. 304 stainless plate with a series of baffles to tie everything together. The pylons that hold together the main mid-support structure needed to be substantial enough to carry the loads. Everything leading up to supporting the wings was reinforced and fabricated from plate. Using bolted connections for everything facilitated shipping and field erection.

LoveBird’s unusual geometry required measuring the exact lengths of the support cables so it could be tethered it to its circular foundation. Four main cables provide most of the support, and 28 smaller ones primarily prevent rotation.

The cantilevered weight of the wings required the main mid-support structure to have gusseted plates at every bolted connection to resist the gravity and wind forces that would be exerted on the wings. The wings are laser-cut perforated panels fabricated from 11 ga 304 stainless steel. Each wing weighs about 900 lbs. The lighted wing tip elements were bolted to the ends of the wings, continuing the tapered geometry.

Reinventing Steel

JAMES KENNEDY CAME TO APPRECIATE the old Champlain Bridge and its cultural significance to Montreal even though he never saw it up close until he moved there in his 20s. He didn’t need to cross it as a child or grow up near it to understand it had meaning to many.

Kennedy, now 50 and a Montreal-based independent structure designer turned steel artist, has spent the last 10 years traveling the world to take pictures of notable bridges and bases his steel art on those photos. Capturing magnificent landmarks and learning about their meaning to locals is his livelihood.

So when he heard about the plans to disassemble and replace the old Champlain Bridge, he couldn’t sit idly.

“I was deeply moved by the vanishing of this iconic symbol of Montreal,” Kennedy said. “I instantly knew that I wanted to create a commemorative piece.”

In 2019, a new cable-stayed Champlain Bridge replaced the steel truss cantilever one that countless Quebec residents crossed for nearly 60 years. The dismantling process began in 2020, and a piece of one side ramp is all that remains. The bridge portion and all the steel are gone, and a cultural symbol for multiple generations left with them. Kennedy understands what was lost, even if he didn’t grow up in the bridge’s shadow.

“A lot of people felt like a big landmark was disappearing,” Kennedy said. “When you cross it all your life, you have memories attached to it. It touched a lot of people. I felt that and connected with that part.”

The federal bridge agency in charge of the project, though, is recycling some of those pieces and awarding them to bidders who present a compelling reuse plan. And that’s where Kennedy saw an opportunity to keep the bridge alive.

Kennedy is building a sculpture, appropriately titled Mémoire, using recycled material from the old bridge. Montreal residents who walk near the bridge’s former site—where he hopes to earn approval to place the sculpture—will see 12 to 15 vertical steel panels made from the bridge’s chords and freshly repainted with a familiar teal tone. The panels will be staggered and perforated with an illustration of the old bridge across all of them.

The main goal of his project, though, is to tell a story. Kennedy is not merely aiming to prop up some beams in a plaza as a tombstone for the old bridge. He wants to connect sculpture visitors with Montreal citizens’ memories and stories of the bridge and, hopefully, make them recall their own. Each panel will have a QR code for visitors to scan and listen to a recording of someone describing his or her bridge memories. All told, the project is as much about discovering the stories as it is about creating the sculpture itself.

“I want to interview people,” Kennedy said. “We all have individual experiences, but it’s nice to see what’s broader. Did someone have a baby on the bridge because they were stuck in traffic?”

About five years ago, Kennedy wrote to Jacques Cartier and Champlain Bridges Incorporated (JCCBI), which oversaw the Champlain replacement, to express his desire to commemorate the old bridge. The agency told him it was holding a material reuse competition and would award some of the steel to citizens who pitched captivating and publicly beneficial repurposing plans.

Kennedy entered his submission in 2020. JCCBI announced it as one of 11 winners in April 2023. In all, he is receiving five pieces of the bridge that weigh about 22,000 lb. All of it was sandblasted and coated with new primer before delivery to his Montreal studio.

Kennedy will not start sculpting until the structure’s location is finalized, but he is targeting late 2024 for completion. The design and timeline were his to determine. It will be his largest project. He has spent most of his time since starting art as a side job in 2008 crafting work that can fit in a room or hang on a wall. Art is now his full-time job.

Steel, though, is familiar material to Kennedy from his pre-artist days. In 2005, he founded his own design and production company that specialized in individual interior spaces and public installations, some of which were made of steel.

“I was fascinated by what we could do with the metal,” Kennedy said. “That started my interest in materials.”

Kennedy merged that curiosity with his artistic passion, which ignited as a child watching his mother, an artist, and grew when he began painting on the side as an adult. He learned many techniques from artist friends, including etching, which he has adapted to create the oxidation painting methods that are now his foundation. His early work included manipulating industrial steel panels into wall sculptures. He now uses several techniques to recreate pictures on steel.

“I’m painting on metal with acids to oxidize the steel,” Kennedy said. “I’m darkening the metal with the type of acid mix I’m using, sometimes creating hues of colors within it.”

His Urban Landscapes series is an assortment of recognizable landmarks he paints with acid on steel and is inspired by photos he took. His Contours series is a collection of continents, islands, and lakes carved into steel. Both include United States locations and landmarks, and he has worked with several U.S. clients. He is currently crafting a commissioned Contours series of all six continents on separate 4 ft by 4 ft steel plates for a company in New York that will occupy 30 ft of wall space. Mémoire will tie everything together in one project—his art techniques, his prior life as a designer, and his appreciation for the steel Champlain Bridge.

“I feel like I’m going back into my old shoes,” Kennedy said. “I’m building something bigger that requires transport machinery and planning. That sculpture links all the experiences I had doing my large projects before.”

“Linking people together—the point of a bridge—is the way I’m going to do this (sculpture),” Kennedy said. “I’m going to link different stories together and build a great collective memory.”

Going Up

A CIVIL ENGINEERING CLASS at the University of New Mexico gave a new meaning to reaching higher.

UNM students enrolled in Civil Engineering 424/524 this fall—taught by Professor Fernando Moreu, PhD—can say they learned about steel design at a higher elevation than any class in the country, and possibly the world. One of their homework assignments was to take Albuquerque’s Sandia Peak Tramway to its 10,400-ft peak to detail its structural components, study its shop drawings, see its machine shop and steel shop, and learn about detailing from the tramway’s maintenance director.

The class has been using the tramway for the last five years, and students are challenged to see steel sections and properties using the 16th Edition Steel Construction Manual in the field. The class challenges the students to think about some of the tramway’s details from the perspective of its function, operations, maintenance, access, durability, and sustainability in the real field. The students were equipped with shop drawings, tape measurers, and a 16th Ed. Manual, and together investigated properties while asking maintenance personnel about their operations.

“Always measure down to 1⁄16 of an inch,” tramway maintenance director Augie Eischen said when he noticed students eyeballing a flange width to be between 11 and 12 in.

Eischen explained the importance of steel detailing and encouraged students to pay rigorous attention to details. Those details impact fabrication and maintenance, so students need to think of steel design in a broader context than the classroom.

“I was shocked when I thought about the operations of the tramway and how the steel design requires the understanding of the car movements, maintenance, safety, and the importance of all possible scenarios,” senior civil engineering student Jack Dugan said.

Added classmate Ethan Kapp: “I enjoyed taking the Tram and using the day to relate equations and the code to real structures.”

Tramway general manager Michael Donovan thanked the students for choosing civil engineering.

“We need your knowledge to design and maintain many outdoor infrastructures in New Mexico, Utah, and the Southwest,” Donovan said. “We have a beautiful country, and you as engineers can create access for people to nature and beauty. Thank you for working with us or others on outdoor structures in nature.”

The class’ midterm asked students to measure the detailed connections and sections from the exposed steel section of the Media Lab at UNM’s Gerald May Department of Civil, Construction and Environmental Engineering. The students sat next to this structure for five weeks and were surprised in the midterm by having to detail it. In the past, students in this class have visited a steel bridge in downtown Albuquerque that carries the Rail Runner commuter train. Their final project is spearheading a new pedestrian steel bridge that will become an iconic entry to UNM’s southwest corner at Central Avenue and University Boulevard.

Shaping The Future

EVERYWHERE CHRIS ECCLESTON goes these days, he sees a reminder of the reality that has spared no one in his industry. Like nearly every other general contractor in the United States, he feels the impact of the trade industry’s labor shortage and its dearth of young workers.

One day, it reveals itself in the form of an office discussion about putting AEDs on jobsites. Another day, it hits Eccleston when he realizes only two to three masons in his region have enough staff to handle the commercial projects that his Salisbury, Md. company tackles.

“In five to seven years, this is going to get worse,” Eccleston said. “We have to start bringing attention to the issues.”

Eccleston, the president of Delmarva Veteran Builders, hatched an idea he hopes will create lasting change. He and Delmarva Veteran Builders creative developer Jenny Schroen wrote a children’s book about construction.

It won’t help Eccleston’s company find more masons for a current or near-term project. Both authors, though, are thinking bigger than a short-term fix and beyond their own company. They want to help end the labor shortage by creating more passion for the trade industry in the workforce of the future. Their book, Grit Leads to Greatness, is an adventure story that they hope will shift perceptions about construction and the trades. They chose the adventure story approach because they felt it would best resonate with children. They wanted to show, not tell.

“We could just write about construction and explain what construction is,” Schroen said. “That’s cool, but how do you cause action and create change?”

Grit Leads to Greatness was published in March 2023. It’s about two children, Tegan and Trig, who live in a dystopian world where the art of building is lost and mysterious glowing stones hypnotize citizens. An earthquake has pushed their home city to the edge of a cliff, and the duo travels to a place called Greatnes, which they believe will save the city. Along the way, they encounter various obstacles. Five fanciful trade-themed creatures befriend them and teach them trade skills that help them pass the obstacles and ultimately reach Greatness.

Tegan and Trig learn masonry, electrical work, plumbing, carpentry, and welding—each from a separate character. Arc the Welder, a robot with flames for hands and a head shaped like a channel, sports a fillet weld diagram on his chest and a welding pack on his back. He teaches them how to weld girders to make a bridge that spans a ravine.

The children in the book learn that trades are essential to every-day life. Similarly, the authors want children who read it and parents who read to them to see the nobility in the profession. To them, shifting parents’ perceptions about their children working in trades is just as crucial as igniting the children’s interest in the trades.

“We’re bringing this honor and heritage back through that heroic lens to a child,” Eccleston said. “That’s what the trades stemmed from thousands of years ago. These were people of high society. That’s now kind of lost. The fact is, we built the world and we’re going to build the future. The trades aren’t going anywhere.”

Eccleston and Schroen wrote the book with two goals: inspire the next generation and activate the current workforce. They’re intertwined initiatives that started with National Read Across America Day in March. About 50 contractors bought bundles of the book and read it to elementary school classrooms in Maryland. Eccleston estimates it reached about 1,000 children that day.

The contractors and tradesmen didn’t just read the book. They told the children about their jobs and their importance. It left children with a new view of the industry and invigorated passion among current workers for helping solve the shortage problem.

“One thing that blew us away is how the men and women of the construction industry responded to it,” Eccleston said. “We had every part of industry represented. We’re a tough group to get excited. The pride, energy, and empowerment I saw from the contractors in the classroom was very moving.”

Publicizing the book and classroom reading days didn’t require Eccleston to devise an aggressive marketing plan. He sent the manuscript to the Associated Builders and Contractors (ABC) and the Association of General Contractors (AGC). He and Schroen went to the ABC’s conference in March to pitch it in person. He emailed local sub-contractors about the classroom readings and found most of them were eager to participate. Every outreach effort landed on enthusiastic ears and spread rapidly.

“We have contractors on the daily finding us and reaching out,” Eccleston said. “We’re starting to get found by different industries.”

Classroom reading days will remain the focus as interest in the book and its purpose grows. The ABC and AGC participated in one in October. A bigger one is planned for March 2024. Eccleston and Schroen have a vision for their next steps too. They’re exploring digitally publishing the book and creating multimedia elements. They’re considering reaching out to more sections of the trade industry.

The most important next step, though, is a simple one. Get more people on board, whether that’s more contractors and tradespeople in the already targeted groups or new ones. They all face the same issue that Eccleston and Schroen set out to change.

“Nobody’s coming to save us,” Eccleston said. “If we’re not going to roll our sleeves up and do the work ourselves, we’re not going to solve the problem. That’s like any construction project. Nobody else is coming to fix the problem. If you don’t figure it out, it’s not getting built.

“This is the same kind of mentality. It’s a great opportunity for us as an industry to come together like we’ve never done before.”

Shaking to the Core

STEEL BUILDINGS ARE designed to stand the test of time. Those located in high-seismic areas also need to stand the test of earthquakes.

The University of California-San Diego’s shake table has become the go-to destination for the latter.

The Large High-Performance Outdoor Shake Table (LHPOST) opened in 2004 and is located 15 miles east of UCSD’s main campus. It can simulate earthquakes and test a structure’s performance under various seismic conditions. It is the largest outdoor shake table in the world and the second largest shake table overall. Its shake area—also called the platen—is 25 ft long by 40 ft wide. It has six degrees of freedom motion capability (6-DOF) and is often referred to as LHPOST6. It can move up and down, back and forth, left to right, and rotate on three axes.

While the action on the table itself is what researchers use to determine performance, the inner workings of a shake table facility are equally fascinating. Several AISC staff members toured the shake table in June, starting with a walkthrough of a support building next to the table and ending with a look below at the various piping channels that carry different fluids to different parts of the table.

Here’s an under-the-hood pictorial tour of the shake table. Machel Morrison, a structural engineering professor at UCSD, and site manager Koorosh Lotfizadeh wrote the captions and explanations. Photos were taken by Modern Steel editor and publisher Geoff Weisenberger, who toured the shake table, unless otherwise noted.

Tight Confines

A BUILDING OVERHAUL that involves tying three floors to a structure next door and anchoring framing into an existing foundation is complicated enough on its own. Perform it on what project manager Greg Riccio characterized as “a postage stamp of a jobsite,” though, and erecting a 107-ton structure becomes an even more complicated undertaking with a longer timeline.

Danny’s Construction (an AISC member erector), with Riccio’s oversight, helped construct a three-story steel building with 26-ft bays on an existing basement frame across from Chicago’s Millennium Park that topped out in May 2023. It replaced a vacant building that was torn down to its basement and sat on an 80-ft by 70-ft plot between Michigan Avenue to the west, Randolph Street to the south, Beaubien Court to the east, and the Millennium Plaza apartment and retail building to the north. It’s in a commercial district with plentiful foot and car traffic during normal construction hours.

“The congested nature of the project was the biggest challenge for us to overcome,” Riccio said.

It was navigable, though. Danny’s and general contractor Power Construction obtained a permit to close Beaubien for about two months, which was enough time to accept just-in-time delivery from AISC member fabricator LeJeune Steel, set framing for all three floors into the existing basement concrete foundation, put up screen wall above the third floor, tie channel pieces into the next-door building’s shear wall to transfer some of the weight, and drill in anchor bolts. Beaubien is a one-block street that sees marginal car traffic compared to the other three.

The crane stayed on site for three segments, each about two weeks, to unload and help erect the framing. It left while workers detailed, bolted, and decked each floor. Steel delivery trucks backed down Beaubien from Lake Street, which sits one block north of Randolph and has less vehicular traffic after it crosses Michigan to the east. Beaubien had sufficient width to fit the crane, but multi-story buildings on two sides of the street gave the crane boom limited range.

“We’re holding these large (up to 16-ft) channel pieces with the crane, so you’re talking about the boom of the crane getting relatively close to the existing structure,” Riccio said. “Trying not to hit the structure took a lot of effort with our ironworkers communicating not only among themselves, but with the crane operator as well to make sure everybody was safe.

“There were a handful of channel pieces where we were working next to a window with an existing business on the other side. Take the extra time, communicate the plan well, and execute the plan. We didn’t have any issues with breaking windows or affecting the businesses.”

Congestion posed problems beyond ground level. The tight space gave ironworkers few safe places to stand while tying the connections to the building next door. Danny’s and Power developed an access plan for the ironworkers to reach the tiein points along the existing building’s shear wall, which had tight clearance between the building and the crane boom. The plan included a boom lift on Beaubien that served as a safe platform to reach the connections. The workers could also safely stand on top of scaffolding on the site’s west side.

Danny’s started its work in January 2023 and topped out the building in May 2023. That’s longer than normal for a small project, but the extra time ensured safety on an unusually tight jobsite.

“You never want to see damage to an existing building or crane and never want to see anybody get hurt,” Riccio said. “The sensitive nature of working along that building and the amount of channels that had to get installed along the face of that building, it takes time, and you want to do a good job and be careful.”

Lamar Johnson Collaborative was the architect, and TS Engineering PLLC was the structural engineer.

Print Preview

THE BIGGEST BREAKTHROUGH yet in 3D printing structures began not as a bid for a construction job, but as an art project created by a software company.

The 39-ft MX3D Bridge over a canal in Amsterdam’s Red Light District made history when it was installed in July 2021. It became the world’s first 3D-printed bridge and the largest structure created using 3D printing. All told, it’s about five tons of structural stainless steel and is the result of collaboration between Dutch structural engineer Arup, Dutch robotic 3D metal printing software company MX3D, and designer Joris Laarman Lab.

Its purpose? Tout a technology that might be a staple of future construction projects. Carrying pedestrians over a canal is a bonus. It was not designed because a government entity that oversees bridges chose 3D printing as its preferred fabrication method for a new canal bridge. Rather, MX3D and collaborative partners Arup, Autodesk, automation technology company ABB, Luxembourgbased steel manufacturer Arcelor Mittal, French industrial gas company AirLiquide, and Dutch construction services business Heijmans birthed the project, and they earned approval for installation over one of Amsterdam’s many canals.

“For us, it was always about the moonshot, not so much about the bridge,” MX3D CCO René Backx said. “It was about showing this technology to the world and having the world work with it.”

Two and a half years later, the Amsterdam bridge remains the largest one constructed with robotic 3D metal printing, also known as additive manufacturing. MX3D remains at the forefront of 3D printing and is active in the United States. It enables companies to print in-house and does on-demand printing. It has U.S. clients and recently printed a stainless steel lunar floor for the European Space Agency designed by Skidmore, Owings & Merrill. The U.S. Army Engineer Research and Development center acquired MX3D technology in October.

Lincoln Electric Additive Solutions is also a prominent 3D printer in the United States and uses a similar technology to fabricate largescale industrial metal parts. It’s a small operation in a giant company, but a corporation of that size investing in 3D printing turns heads.

“When you start to see big-name people in the industry make investments like that, it certainly helps push things forward,” said Ryan Sherman, a Georgia Tech civil engineering professor who has extensively researched 3D printing.

MX3D’s successful venture has sparked curiosity about 3D printing’s potential to become more prominent in the structural steel industry, especially with bridges. All told, it’s still a fledgling technology, but one that has researchers’ attention. Sherman, whose research earned him the 2023 AISC Milek Fellowship, sees it as part of the future. But not the entire future.

“It could be a tool that the steel industry could leverage and put another tool in the toolbox to give us more capabilities,” Sherman said. 3D printing manufactures solid objects layer by layer while working directly from a digital model. It’s called additive because it does not need a block of material—such as steel—to create a three-dimensional item. Printing steel parts or structures requires turning welding machines (or welding robots) into 3D printing robots that turn welding wire into steel.

“You just need to connect the welding machine to a robot,” Backx said. “On the robot, you need to control the kinematics, like how every robotic joint is positioned. On the welding machine, you only need to set the start and stop of each weld line. Together, that enables 3D printing.”

“Starting to print is easy,” Backx said. “Quality prints take good tools, good workflow, good knowledge, and good materials.” The more complicated and specialized parts of 3D printing start with the robots’ settings. Each type of wire and each design requires different parameters.

“You need to know what settings are required for specific wires to get quality prints,” Backx said. “For instance, if you want to make thinner lines, you need to go slower with different settings. Aluminum needs to have a lower temperature for welding than steel. Temperature control is always important.

“The wire feed speed is another parameter setting. How fast do you want the spool to get? If you go too fast, you could have a lump.”

Developing those parameters and programming welding robots to 3D print metal took time and trial-and-error. MX3D specializes in robotic wire arc additive manufacturing (WAAM) and created software to go from a CAD model to a printed part. The software contains parameter settings for various materials and printing strategies, so a user only needs to upload the design and select the specific robotic setup, wire type and strategies. The software generates the optimal robotic print path to start printing in a controlled manner.

Any weldable wire is suitable for 3D printing, but the wire quality makes a difference in the final product. MX3D printed everything but the bridge’s non-metal deck with stainless steel 316L wire at a warehouse. A team of four robots and five people—two were robot supervisors—began printing the bridge in March 2018 and finished in about six months. It was printed in several pieces.

MX3D hit the six-month timeline working only during the daytime. Newer technology allows printing at all hours, and one operator can supervise four robots.

The Amsterdam bridge was MX3D’s first venture into structural steel. It worked with Joris Laarman Lab, an art collective that 3D prints metal sculptures in organic shapes. One of Joris Laarman’s early projects was a chair designed in organic shapes and printed in small sections with laser powder bed fusion in 2006. The lead artist wanted to make something bigger upon the release of more sophisticated technology. Joris Laarman and MX3D settled on a bridge.

Printing a usable and sound bridge, though, is a rigorous test compared to small parts or sculptures. The bridge is a mix of artistic ideas with structural engineering principles, and the latter took priority.

“You can go crazy with 3D printing, but in the end, you need to get it certified and prove it’s structurally strong enough,” Backx said.

At the time, nobody could say with certainty that a 3D-printed bridge would be stable, pass tests, and earn certification. There was no precedent for building a bridge with additive manufacturing. There are no additive manufacturing building codes. One test or certification failure could have ended the entire project and shifted the construction industry’s view of 3D printing. MX3D wanted to try anyway, and the necessary City of Amsterdam governing bodies approved the project for placement.

“We’re grateful for the risk they took, because at that time, there was no clue if we could make the certification or even print it,” Backx said.

MX3D put the bridge project through three years of tests, enlisting a network of partners that included Arup, researchers from Imperial College London and certification experts from Lloyd’s Register (now LRQA). It has previously worked with inspection and testing company Bureau Veritas and classification society DNV to certify strategies and parts used in energy and maritime projects.

The certification checklist is lengthy. The printing strategies needed to be certified. Material needed to be tested for strength in a lab, chemical tested, and load tested after construction. Every connection was tested. MX3D had to prove the material would not corrode, which Backx said was the most difficult test to pass. The wire type dictates the printing strategy, and a less commonly used alloy might require a rare or exclusive printing strategy that needs certification.

“There are no standards yet, and that’s a main reason [3D printing] is not widespread yet,” Backx said. “Whenever it has standards for how strong 3D printing is for specific materials, we’re sure the technology will grow in construction and other industries.

“When there are no standards, more time and money are required to certify specific parts and structures.”

But MX3D proved the whole process is navigable and met its goal of introducing a new technology. Widespread adaptation will take time. And even when it arrives, nobody is predicting a takeover.

“3D printing is not there to replace all conventional technologies,” Backx said. “Speed, money, time, cost—all of that is important. But it’s an alternative way to do fabrication. If you need a part that’s more complex or optimized, or have a project where lead time or material waste is high, 3D printing will help. It can also create designs that are not possible with more conventional technologies.

“Where we see the future is a combination of these different manufacturing processes. For steel, robotic 3D printing will be used where it offers the best value and when other technologies simply can’t fabricate it.”