9 minute read
More Than Just Architecture
HUCKABEE BALANCES CRITICAL NEEDS OF ARCHITECTURE AND STRUCTURAL ENGINEERING TO DESIGN STATE-OF-THE- ART STORM SHELTERS REQUIRED IN K-12 SCHOOLS
By Craig A. Shutt
Huckabee has long been a leader in designing state-of-the-art K-12 school projects in Texas that adapt to evolving teaching curricula. That work includes providing a storm shelter in projects that meet specific codes and requirements, and incorporating these as functional space that fits a creative environment. Fortunately, vice president of engineering Benchmark Harris not only enjoys the challenge those requirements produces, he sees it as his mission to develop new designs to share with designers nationwide.
The 2015 and 2018 editions of the International Building Code incorporated a requirement that newly constructed buildings and significant additions to existing schools in high-wind zones must include a storm shelter that complies with code requirements. As many communities in North Texas are located in these zones, administrators began looking to meet the requirements in a cost-effective way. Architects and engineers at Huckabee seized this opportunity.
“At Huckabee, we have done a lot to promote effective storm-shelter designs,” Harris says. “There is a great deal of K-12 construction in Texas, and administrators need answers about where and how to protect students during a storm. As this need developed, we made it our goal to help administrators across the nation work with emergency planners when designing storm shelters.”
That desire fit well with Huckabee’s philosophy of evolution and innovation. “Huckabee is something of a contemporary to the original Bell Telephone Laboratories, which had an attitude of investing money in ideas and had a tremendous success rate,” he says. “Our leadership invests money where we see potential for innovation. Some people find it strange that an architectural firm takes on some of these research projects, but we do much more than just architecture.”
Tragedy Offered Catalyst
Huckabee’s focus on storm shelters ratcheted up in 2013, after a massive fertilizer plant explosion in West, Tex., damaged hundreds of buildings, including three of the school district’s facilities. While some were renovated, the high school was demolished and rebuilt into a combined high school/middle school campus, complete with a precast concrete storm shelter.
Opened in August 2016, the school features a regulation basketball court constructed with precast concrete panels and double tees, which offered the floor plan area required for a shelter while creating large, open areas uninterrupted by columns or additional bracing, making it easier to supervise the students.
“The thickness of the precast concrete walls provides a fortress of security during a tornado event, and the smooth texture of the concrete walls creates an ideal surface for paint, graphics, and wall padding,” says Greg Gaskie, an architectural associate with Huckabee.
This early work, along with the 2015 code changes, pushed these designs to the forefront at Huckabee. “I became a lightning rod for developing standards and processes that could result in the successful collaboration of various design disciplines on tornado shelters,” says Harris. The entire industry is moving forward, in conjunction with the National Storm Shelter Association (NSSA), Harris notes. “Storm shelters are a new concept for many school districts. Administrators aren’t sure what they need to do.”
A key approach for Huckabee’s designers has been to take a programmed space and design it so that a multipurpose space, such as a gymnasium, also serves as the shelter. This is applicable where design wind speeds are 250 mph and associated with EF5-level tornadoes, the maximum rating on the Enhanced Fujita scale of tornado intensity, in the highest Tornado Alley-type zones. The design, which meets the needs of many Texas schools, features wind-pressure and impact-protective systems such as tested door assemblies.
Overcoming Myths
In meeting storm requirements, he stresses, it’s important to overcome myths that lead clients in the wrong direction. “It’s easy for administrators to see generic FEMA [Federal Emergency Management Agency] guidelines that were intended for use with older structures without tornado shelters, and not realize that those guidelines do not apply to a new structure with a tornado shelter.”
Because of that guidance, schools will sometimes start by thinking they need several smaller spaces as the shelter. “It’s an understandable approach, but some emergency planners recommend having everyone in a large, open space so that students are more easily supervised. If the shelter is designed for the open geometry, it’s an acceptable place to protect students.”
The larger gymnasium shelter space will typically have a higher cost per square foot than a classroom shelter, he notes. “However, the cost increase per occupant to provide the shelter is actually less for gymnasium shelters in our experience.” The actual usable space is less per square foot for classroom spaces because there are desks, chairs and other equipment, requiring more overall square footage to meet the usable space-per-person requirement.
“When all factors are included, it makes more sense to use a large space like a gymnasium.” To further enhance cost-effectiveness, Huckabee designs its storm shelters using precast concrete components, including beams, columns, double tees, and panels. “All things being equal, precast concrete offers the best cost-effectiveness for these gymnasium shelter spaces in our experience.”
A space designed with precast concrete components can fit into any type of learning environment, he notes, providing every school with a protected, easily supervised space. In an elementary school, this design can be an activity room; in middle school projects, it often doubles as the gymnasium. For high schools, it is often designated as the practice gym or gyms, which do not have as much seating as a competition gymnasium.
This consistent design aids users if the school system elects to make all tornado shelters be precast concrete gymnasium shelters, as students are more likely to know where to go for shelter no matter what school they’re in. “There’s a synergy that develops because the space is cost-effective, the appropriate size, and in a
recognizable location,” he says. “As kids move through the grades and schools, they recognize the shelter space and don’t have to be directed where to go.”
These spaces provide the right boxy shape and size for a storm shelter, but it’s not necessarily that easy. “Some provisions are written in the standard as if the shelter is always a rectangular prism, and that’s not always true. We often have to adapt our standard design ideas to fit the individual school’s needs.”
A recent example is the Dr. Sarah K. Jandrucko Academy for Early Learners in Mansfield, Tex. Huckabee worked with Bartlett Cocke General Contractors to create a 54,000-ft 2 , prekindergarten facility that resembles “a hands-on children’s museum with dedicated themes” carried into decor and interactive exhibits, according to the contractor. Four thematic pods branch into 16 classroom environments.
The storm shelter was fit into this environment by designing it to serve as a multipurpose activity room, because there is no “gymnasium.” The precast concrete structural system, including panels and double tees, can withstand 250-mph winds and airborne debris. It also features storm louvers in the walls that resist the standardized 2 × 4 design tornado debris while allowing air to circulate.
School Versus Shelter
Inserting this type of highly structural element into a building’s architectural plan often leads to design challenges because the shelter’s needs are so different from those of a school. Harris is working to assist design professionals with these challenges through speaking engagements at conferences and participation with organizations, especially NSSA. The group, for which Harris serves as a vice president, provides educational resources and other support for designing storm shelters.
“There is enormous interest from not only designers and structural engineers but also owners, contractors, emergency planners, and first responders.” They need as much guidance as they can find, he says. Many of the standards being applied to storm shelters were originally written for FEMA-funded safe rooms, which don’t necessarily have the same purpose or standards.
“In some ways, it’s the wild, wild West out there,” he says. The code includes many gray areas that can be interpreted liberally or conservatively. “That doesn’t help anyone determine if they’ve achieved an effective solution. Designers don’t want to under-de- sign, but they also don’t want to over-design. Neither is an acceptable outcome in an owner’s eyes.”
Fortunately, a standard of care is developing, and Harris is helping accomplish that in conjunction with NSSA. The group is creating white papers to post online to help define practices.
“We have attended building code hearings and NSSA has attended other group conferences to be proactive, taking in comments and receiving input from many perspectives,” he says. “We hope that will result in significant changes that will register with code officials.”
Developing Standard of Care
Harris also is working with several structural engineering firms as part of a group within the Structural Engineers Association of Texas. “SEAoT’s preliminary efforts have been well received and there has been good feedback from structural engineers around the country.”
Some of these concepts are now being reviewed by NSSA’s Design Practices Committee to be forwarded for consideration by various code bodies. Some have already been considered and approved by IS-STM, which is the International Code Council committee that oversees ICC-500, the standard for tornado shelter design.
Huckabee’s own concept has evolved as new ideas, techniques, and products have arisen. It’s now into its fourth generation of design, which is customized to each client’s needs. “The engineers work closely with the architectural side to create an attractive building that works better than the code requires,” he says.
“We think we’ve developed a best-practices approach that we can keep improving.”
Among its concepts is the use of lower heights for parapets, which can catch windborne debris. One façade is typically designed without any parapet so water can flow to an area with less concern about ponding. The firm also specifies a multiple storm-louver baffling system to handle small windborne debris in addition to the standardized 2 × 4 design debris.
“Our architects and structural engineers think holistically about the building, balancing standards for the shelter with those for the school functions and sincerely address both sides,” he says. Huckabee’s in-house structural group aids that process. “Many architectural firms sub out their engineering and give them a defined scope of work, which makes it harder for them to see the big picture and provide the same level of integration that we can offer by doing this together.”
The challenges can be seen in such basic areas as reviewing shop drawings. Typically, a structural engineer wouldn’t review a door’s drawings. But when it must meet storm-shelter code requirements, those duties can change. “The review may require either or both, depending on the company’s processes.” (NSSA’s position is that the structural engineer should be involved with the required wind-pressure rating, and a future white paper will clarify recommended roles and responsibilities with submittals.)
New products offer a unique challenge. Huckabee evaluates many on its own, providing feedback to vendors. “We’re very proactive with examining new concepts and products to incorporate into our plans,” he says. “We’ve developed a strong relationship with vendors to explain what school districts need, because our clients benefit from those changes.”
Product enhancements can be difficult to enact, he notes, because changes involve costs for vendors, and the certification process can be long and expensive. “They have to really be invested in providing products that offer the best level of protection possible and work with the certification bodies to get their products approved. Complex assemblies can be difficult to change.”
To aid this, NSSA is working on an Impact-Protective System and Construction Assemblies database that identifies products/ assemblies that are successfully tested and offers guidance on how to apply the standards using various products/assemblies.
As Huckabee’s design concepts evolve, so too does the company. It currently operates six offices, which have opened organically as clients developed in a region, spreading out from its Fort Worth base. “Growth in local interest is the primary reason we open a new office,” Harris says.
As more schools are required to incorporate tornado shelters and as school designs evolve, so too will the designs for Huckabee’s shelters. “We’re here because of the students. They drive every aspect of our firm and they’re the reason we’ll continue to innovate.” ●
