Taking Precast to the Next Level

Coreslab Structures

Coreslab International is an industry leader in the manufacture of precast and prestressed concrete components. With eighteen plants across the United States and Canada, the company offers a wide range of related services, each location specializing in the services best suited to their particular markets. The company is a leader in innovation and structural design committed to providing its customers with the highest quality of service.
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Established in 1990, Coreslab’s Oklahoma plant specializes in commercial projects, offering both structural and architectural components for churches, schools, office buildings, parking garages, stadiums, storm shelters, and a wide range of other projects that make use of precast concrete. In August of 2015, Coreslab and a group of leading companies including multidisciplinary engineering firm CEC, precast design engineering firm Unintech, architect and design firm REES Associates, and construction management company Manhattan Construction, were brought on board to build a new broadcasting facility for Oklahoma’s KFOR Channel 4 News station.

The building was designed to withstand an EF3 tornado with wind speeds of up to 165 miles per hour. “The main purpose of this building was to enable the newscasters to stay on the air and broadcast through a tornadic event,” says Coleman Harrison, Project Coordinator with Coreslab. “The building that was there previously was a 90 mile per hour wind design that they had been broadcasting out of since 1949.”

At a total of 49,000 square feet, including the mechanical mezzanine areas and a covered parking structure to give their vehicles protection from hail storms and debris, a total of 323 precast components were manufactured and used in the construction. The new facility enables the station to continue providing important news updates to its viewers during tornadoes that are capable of causing severe damage. An EF3 tornado is capable of uprooting trees, lifting cars, and tearing the roofs off even well-constructed facilities.

A group of five companies were involved in the project superstructure. CEC out of Oklahoma City handled the civil and structural engineering on the job. “We can do everything on the building except the architecture itself,” says Chris Snider, the structural engineer of record with CEC. “We try to focus on relationships because we know we’re going to see the architects, contractors, and precast manufacturers on many projects throughout our careers. Doing what it takes to make sure everybody is successful is something that’s really important to us.” CEC has been recognized by Oklahoma ACEC (American Council of Engineering Companies) with awards for numerous projects, demonstrating its expertise and the quality of the work it performs.

REES was the architectural design firm for the entire project. Short of the news station’s specialized broadcast equipment and set design, REES designed everything. The company is a national design firm specializing primarily in senior living, healthcare, corrections, security, and broadcast architecture. “We don’t design cookie cutter projects,” says Dennis Metheny. “Every project is uniquely designed.” REES has been recognized for its expertise numerous times, having won a Firm of the Year award from AIA Oklahoma, and an IIDA Pinnacle award to name a few.

The construction manager at risk for the project was Manhattan Construction, one of the largest privately held construction firms in the United States. The company won an ABC Oklahoma “Excellence in Construction” award in the ten to twenty-five million dollar category for its contribution to the KFOR station project.

Unintech Consulting Engineers designed all the precast components that Coreslab manufactured for the structure. Unintech is a design and consulting firm with more than 26 years of experience focused on providing quality value to customers in both the public and private sectors. The company offers structural, civil, and surveying services, but worked specifically on precast design for the KFOR project.

Finally, Coreslab Structures was responsible for the manufacture and installation of all the precast concrete elements for the project. A major provider of structural and architectural concrete products, the company has more than forty years’ experience supplying both the Canadian and U.S. markets. The majority of the shelters designed by Coreslab have been gymnasiums for schools, but it has also built classroom pods, band rooms, cafeterias, a pom and cheer facility, an add-on shelter to the student housing facility at Oklahoma University, and a number of other structures. The company has its own engineering, drafting, and estimating departments so it does a great deal of front end work with customers, even during the design phases of a project. By working with Coreslab, customers can take advantage of its expertise toward developing a project that is more precast-friendly and, as a result, more economical.

All of the companies involved in the project have a great deal of experience and well-honed expertise in developing shelter structures designed to withstand tornadic events. Coreslab has manufactured components for, on average, a dozen shelters per year for the last five years or more. Those structures are typically designed for 250 mile per hour winds to meet the requirements of the international code council ICC500 standard. Many of those structures are gymnasiums for schools that are designed to double as the tornado shelter for that school’s entire population. These structures can withstand an EF5 tornado. “We’re very familiar with high wind design,” says Sean Morris with Coreslab, “so for this structure, we were able to easily accommodate the component requirements for the building.”

The key difference between this project and the shelters typical of what Coreslab has worked on in the past is that the company is not normally involved in the architectural finishing. “They usually just want a structural grey wall,” says Morris. “On this one we had the luxury of having the architectural finish be a part of the structural wall panel, so it served double duty. Because we’re designing for 165 mile per hour winds we didn’t have to worry about debris impact resistance and all the things you’d have to worry about with other tornado shelters.”

Still, the project wasn’t without its challenges. As a television station, the facility had to be equipped with large exterior transmission dishes roughly three meters in diameter, which are a unique load that must withstand significant uplift forces when winds reach high speeds – and particularly during a tornado. “From a precast design perspective the main issue was the 165 mile per hour EF3 wind loads we had to account for,” says Brad Aldridge with Unintech. “It required 88 pounds per square foot (psf) of downward wind pressure, and 115 psf of uplift on the roof components. In addition we had to account for 50 psf debris loading on top of the roof. To put that into perspective, for a normal garage that we’d do, we typically design for a live load of 40 psf and that’s assuming you have cars parked at every space and all your driveways are full of vehicles. The debris loading on the roof was a larger requirement than that, and we’re spanning 78 feet of the roof.”

Overall, from design to completion the project took from August of 2015 to May of 2018 and was built in two phases. The first phase was the construction of most of the new facility, enough to operate the station out of, and took roughly two years to complete. When the station began broadcasting from its new location on August 1, 2017, phase two began. This consisted of the demolition of old building, the completion of the new site, and parking including a covered garage. The station was open and operational for more than ten months while the project was still underway, which presented its own challenges, but the team was able to complete everything to specification.

Despite these challenges, the companies involved are experts in collaboration. It was a team effort that depended on effective communication between the client, the engineering and design teams, architects, contractors, subcontractors, and more. “Everyone had to work together at all times to make the project successful,” says Dennis Metheny.

After three years of dedicated teamwork, the KFOR station is fully operational, broadcasting important news to the viewers in its region. On February 15, Coreslab Structures was presented a “Best of Precast Concrete” award for the KFOR Studio project at the annual Precast Concrete Manufacturer’s Association (PCMA) Awards Banquet in Austin, Texas.

While this project represents only one of many storm shelters that the companies involved have designed and built to protect people from dangerous weather events, the KFOR channel 4 news station facility is a source of great pride. “Because it’s a news broadcast center, our designs allow the news station to stay on the air and help protect the lives and property of the people in their broadcast area,” says Chris Snider. “The building we engineered and built will help to keep the public safe.”

Building the Next Generation

As thousands of experienced workers retire across North America every day, it is small wonder many industries are concerned about the future. It has been a decade since the oldest members of the baby boom generation started leaving their jobs, removing from the workplace decades of experience and skills that are tough to replace. The situation is so dire that, when younger workers are not available or knowledgeable enough to take over, retired staffers are often called back to work on a part-time basis.

November 12, 2019, 10:34 AM EST