By Scott Collins, PE – Chief Engineer, North America, Leviat

This is the first in a planned series outlining the history, advances, and innovations witnessed by the tilt-up construction industry from its inception in the early 1900s through its remarkable growth over the past century.

Much of the following article was made possible through the writing and personal accounts of David Kelly, former chief engineer at Meadow Burke (now Leviat). David’s gracious contributions to this project have been invaluable, offering a wealth of firsthand knowledge from one of the leading figures in the history of tilt-up construction. 

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The humble tilt-up brace is one of the most iconic components in North American construction. Visible even from a distance, rows of towering, angled, steel braces indicate the telltale sign of a tilt-up project under construction.

While the modern brace may seem like a simple solution at first glance, its development mirrors the evolution of the tilt-up industry itself: progress marked by fits and starts, driven by job-site safety, advances in materials and technology, and the ever-increasing complexity of project and panel physics.

Brace Beginnings

Prior to the mid-1950s, tilt-up panels were normally braced with makeshift supports, often using fixed lengths of lumber or steel pipe. This was a taxing, time-consuming process, as the newly erected panels had to be held plumb by the crane until the rigid bracing components were fixed into place. Constant oversight and adjustments were required for each panel before the crane rigging could be released and moved to the next location. 

Over time, contractors developed an adjustable wood-hardware setup consisting of a swiveling top shoe that could be bolted to the panel and bolted or nailed to wood shoring. The lower unit also had a swiveling shoe that could be bolted to the floor and was attached to a turnbuckle. This unit allowed the panel to be erected, so the bracing could be attached, and the crane rigging could be released, and then final adjustments could be made using the turnbuckle to plumb the panel. While this was a definite improvement over fixed-length lumber, these adjustable wooden structures were still limited in strength.

Pipe Braces

The first adjustable pipe brace was likely the “A” Brace, which was developed by Richmond Screw Anchor and furnished to contractors by its dealers. This brace was composed of a fabricated lower shoe attached to an Acme threaded turnbuckle with 9½ inches of adjustment.

This was attached to a 10’ long, 1½”ø schedule 40 pipe with ⅝-inch adjustment holes every 6 inches. This was slipped inside a 10’ long, 2”ø schedule 40 pipe with a fabricated swivel shoe on the top. The “A” Brace could be adjusted in length from 12’ to 20’ 6”, but its overall capacity was significantly diminished by the 1½”ø pipe with all the holes in it.

In 1962, Burke Concrete Accessories developed a “B” Brace that replaced the smaller diameter pipe with a 1½”ø schedule 80 pipe and placed the series of holes in the larger diameter 2”ø pipe. This brace was about twice as strong as the “A” Brace.

As contractors began casting taller tilt panels, Burke developed add-on extensions that lengthened the “B” Brace’s maximum reach to nearly 31’. At theses longer lengths, however, field-built knee braces and cross-laces were often required to provide adequate load capacity. 

Modern Brace Design 

In the mid-1970s, tilt-up bracing underwent another evolution that would allow for easier and faster adjustments and increase overall durability.

First, the turnbuckle assembly and easily damaged Acme threads were replaced with an adjustment screw with Dywidag thread (17.5” of adjustment). This thread is virtually indestructible due to its extreme hardness and thread pattern. It also allows for faster adjustments due to its greater pitch.

Adjustment bolts were no longer needed to slip one pipe inside the other. Instead, a swivel was engineered for the top of the braces, and adjusting the brace for length was as simple as rotating the whole outer pipe around the adjustment screw. The fabricated wall connections were swapped out for less costly castings, and the new, more robust braces became truly reuseable. 

Using this new design, Burke developed the Little G, Standard G, and Big G braces with a variety of interchangeable components to obtain lengths from 13’ 6” to 39’. All three variants used smaller pipes of 2”ø schedule 40 and larger pipes of 2½”ø schedule 40, Dywidag threads, and cast shoes. Knee braces and cross-laces were still often required to meet load capacities.

The 1980s saw Burke develop the Super 22 brace with a fixed length of 22 feet, which was made from a single 3½”ø schedule 10 pipe, a Dywidag thread, and cast shoes. Due to the thinner and larger diameter pipe, the Super 22 was stronger, lighter, and less expensive to manufacture. The Burke Super 17 soon followed. It was stronger, lighter, and 30% less expensive to produce than the Super 22 while still meeting the same requirements of 70% of the panels that had been achieved by the Super 22.  

Meeting Customer Demand

By the 1990s, designers and engineers began to push the envelope of tilt-up construction. Not only was the method exploding in popularity, but new finishes, complex geometry, and ever-taller panels were becoming more prevalent.

Faced with this new age of tilt-up construction, contractors and construction-supply distributors turned to brace manufactures with a wish list of requirements for durable, reusable braces that were stronger, longer, lighter, and easier to use.

For the Burke team, this meant working hand-in-hand with customers to perfect the next advancements in brace design. Burke’s chief engineer, Dave Kelly, played a prominent role in that initiative.

“The Burke Super 32 brace was developed directly with input from Lou Boldt, who was leading Form Services at that time, a longtime tilt distributor in the Baltimore area,” recalls Kelly. “He thought a 32-foot brace would be ideal for a number of jobs he had coming up, and he was ready to place an order if Burke would design and manufacture them.” 

That partnership would prove extremely successful. 

The Burke Super 32 launched in 1996 and featured a fixed length of 32’, made from a single 5⅝” ø schedule 10 pipe. Due to its thinner and larger diameter, the Burke Super 32 was stronger and lighter than previous braces and rarely required the knee bracing and cross-lacing found on earlier projects. 

“After we produced the first order of Super 32s, and Form Services started selling them for projects, everyone wanted them, so they became another standard industry brace length,” said Kelly.

The lockstep progression of architects designing taller panels, contractors demanding longer braces, and manufacturers answering the call continues to this day. 

“The knowledge we gained from the Super 32 line definitely helped spur subsequent brace lengths,” said Kelly. “But the later Super 37, Super 42, Super 52, and Super 62 braces were definitely the results of our clients continuing to expand the tilt-up method and redefine what it could be used for.”

Formal Guidelines

Another key brace development was the publishing of the first Tilt-Up Concrete Association (TCA) Bracing Guidelines for Tilt-Up Concrete Construction. Drafted and released in the mid-1990s, the document sought to standardize bracing operations and establish a common set of safety considerations and best practices for contractors to employ when erecting tilt-up panels. 

Now in its fourth edition, the TCA Guideline for Temporary Wind Bracing of Tilt-Up Concrete Panels During Construction is the industry standard for guidance in the bracing of tilt-up panels and offers the basis for recommendations by the US Occupational Safety and Health Administration (OSHA).

Technological Advances

Tilt-up construction in the 21st century continues to rapidly evolve, with soaring panel heights serving as a key indicator. In 2000, the TCA’s database of projects listed only one known tilt-up building with a panel height above 65 feet. Today, that list includes nearly 150 such buildings. In 2015, a student dormitory at Florida International University in Miami featured multiple tilt panels that were over 110 feet tall, which currently holds the record. 

Panel weights also continue to climb. A 2021 Northrop Grumman manufacturing facility in Arizona featured a mammoth tilt-up panel that tipped the scales at 504,000 lbs. 

To meet these rising demands, brace manufactures have also evolved to offer advanced materials and custom solutions. Additionally, computer-aided design now offers precise calculations that tailor each brace to the specific requirements of the panel it is used on.

The integration of network-connected smart technology may also become standard practice, with integrated sensors monitoring brace loads in real-time to improve performance and overall safety.

Bracing for the Future

The history of tilt-up braces and bracing design is a testament to the industry’s ongoing commitment to innovation, efficiency, and, most importantly, safety. 

From the early days of makeshift wooden supports to today’s 21st-century, computer-aided designs, the evolution of bracing technology has played a critical role in the success of tilt-up construction. 

As materials and technology continue to evolve, the only certainty is this: That the next advance in brace design will be driven by the imagination and determination of today’s best and brightest tilt-up industry professionals.