By Madelynn Coldiron
If an architect or engineer designed a space within a school for a tornado shelter, it might look a lot like…a hallway in a regular classroom wing.
“The type of space you design would be like a corridor – relatively small, heavily reinforced for its size, very little span so the roof system that is supporting it, for its width, would be anchored very heavily,” said Tim Lucas, former school architect and staff architect for the state education department’s facilities division.
“From a structural standpoint,” said KSBA Risk Management Director Myron Thompson, “I do believe schools are relatively safe, but we still need to make sure that we avoid spaces like gyms and cafeterias with open spans.”
PHOTO: The library at Herald Whitaker Middle School in Magoffin County was left exposed to the elements following the March 2 tornadoes.
The schools that were hit by the March 2 tornado in Magoffin County, “remarkably, did much better than some of the other surrounding adjacent things in the landscape,” said Mike Sparkman, president of Lucas/Schwering Architects in Lexington, which is working with the district.
While the state building code has continuously improved over the years, schools are not required to function as storm shelters, said structural engineer Ethan Buell, president of BFJM, Inc. in Lexington, who also sits on the state Housing, Buildings and Construction Board.
As the code upgrades, existing buildings are not required to upgrade with it unless they undergo a significant renovation. The three schools hit in Magoffin County were a typical mixture of reinforced and unreinforced masonry, with the level of reinforcement determined by the year each was built, Sparkman said.
It was easy to tell under which set of building codes the damaged schools were built, said Buell, who also is assisting the school system.
“The ones that were most heavily damaged were the unreinforced ones,” he said.
A newer type of poured-in-place material called insulated concrete form has been used primarily for its energy-saving capacity, but it also is believed to stand up to storms better than reinforced concrete block masonry.
Architect Martha Tarrant, president of RossTarrant Architects in Lexington, said because the interior finish is drywall and not block, it wouldn’t be used in areas such as a gym. Districts also should be aware that state building code does not require continuous inspection of insulated concrete form construction while it is being installed, said Buell, who is hoping this will change.
While building code does govern design for wind load, it’s not that simple, according Tarrant.
“The code requirements are dictated not just for wind speed, but wind uplift pressure,” she said. “The building location and surroundings – in an open field versus surrounding buildings – play a part in determining how wind speed affects wind uplift pressure.”
The code also has requirements for design of the roof as well as roof coverings, Tarrant added, which is why it’s important to have both an architect and a structural engineer involved in designing wind loads for buildings.
“If you read the statistics, in these storm events it’s not necessarily the tornado that gets you, it’s the things flying through the air that gets you hurt,” Sparkman said.
At least one district has gone a step further in minimizing that scenario and increasing the shelter capabilities of schools. Fayette County Schools requires a shelter in place area with a higher degree of protection in all its new buildings and new additions, said Christopher S. Kelly, president of Poage Engineers & Associates in Lexington.
“I think it’s a good idea to create some extra safety areas in design,” said Kelly, whose firm, in addition to working in Fayette County Schools, is doing post-damage review in Morgan County Schools.
That’s accomplished in main corridor wings by putting a concrete slab layer between the metal deck overhead and the roof, he said. It provides enough shelter space for the children in the adjacent classrooms.
“That creates an area that is much, much higher than the typical wind design,” Kelly said. It also provides a concrete layer of protection from debris that penetrates the roof or flies in when winds peel off the roof.
“It would take quite a hit to penetrate the slab,” Kelly said.
In a building addition, however, a reinforced corridor cannot accommodate the entire study body. In a recent addition to a Fayette County school, Kelly said, two windowless resource rooms along with the new corridor were reinforced, which created enough space for all students to shelter.
Glass is among the flying debris when windows are broken. Windows were shattered by wind-borne debris and projectiles in three of Magoffin County’s schools, Sparkman said.
Corridors with a doorway or window or combination of both at each end pose a special hazard, he said, creating a wind tunnel when blown in. One option in designing a school is to place them at a right angle around the corridor’s end.
“That way if there is wind-borne debris, it would fly through or break the glass and just hit the adjacent wall on the other side – it would not fly down the length of the corridor and hit somebody,” Sparkman explained.
Tarrant said laminated glass also can be used in windows or a film can be applied to existing window glass to better withstand breakage in storms. More and more glass is being used in schools, she said, both for energy savings and improved student learning with natural daylight.
“Rather than compromising the educational aspects of the design and natural light in the entire building, what a lot of schools do is consider making sure there’s someplace in the building where children can go to be away from glass in case of a major storm event,” Tarrant said.
The extent to which shattered glass is a problem is illustrated in Magoffin County, where school officials may have to excavate several inches of soil off the top of a ball field because it’s the only way to remove all the shards of glass lodged there, Buell said.
KDE’s Lucas said it’s typical for building code changes to follow severe storm outbreaks such as this, after the insurance and design industries evaluate the damage.
“I’m sure there will be some data there that will go back and cause people to think differently about how we design certain buildings,” he said.
Building codes factor in wind design with every generation, Kelly said. “And every time we do have disasters, whether they be nationwide or worldwide, the engineering community seems to learn different ways to approach design,” he said. “Sometimes it’s just little detail things that we find – (such as) in practice, this really helps keep the roof on.”
— For guidance on selecting refuge areas in existing buildings and designing shelters for new buildings, click here and use the “search by publication number” tab at left for FEMA 431 “Tornado Protection: Selecting Refuge Areas in Buildings,” and FEMA 361: “Design and Construction Guidance for Community Safe Rooms.”