STORM SHELTER DESIGN – TAKE AWAY FROM THE 2021 NSSA STORM SHELTER CONFERENCE

IES attended the 2021 Storm Shelter Conference in Dallas, Texas November 15th – 17th, presented by the National Storm Shelter Association (NSSA). At this year’s conference, NSSA introduced two new credentialing programs. We asked our attendees for their key takeaways and thoughts on storm shelter design and the credentialing process.

You attended the NSSA Fall Storm Shelter Conference in mid-November.  What was your biggest take away from your time at the conference?

The International Building Code starting in the 2015 edition has required certain types of buildings such as 911 call centers and K-12 schools to provide tornado storm shelters. Storm shelter design is a multidisciplinary effort to address the hazards associated with hurricanes and tornadoes; including high winds, flying debris, falling and laydown hazards associated with the structural collapse of adjacent structures or trees, flooding and storm surge, and fire. The storm shelters designed under the 2020 ICC-500/NSSA Standard for the Design and Construction of Storm Shelters balance occupant safety, constructability, maintenance requirements, and human factors to ensure a minimum level of performance during a storm.

We understand that you are working on your certification as a NSSA Accredited Professional.  What does that mean?

A designer holding the NSSA Accredited Professional (AP) credential has demonstrated training and competence in the design of storm shelters under the 2020 ICC-500/NSSA Standard for the Design and Construction of Storm Shelters. For a Structural Engineer to obtain the NSSA AP credential, they much take and pass the NSSA AP General Exam and NSSA AP Structural Engineering Exam, agree to abide by the Code of Conduct for NSSA Accredited Professionals and Certified Inspectors, and submit evidence of serving as the Structural Engineer of Record for the design or code-required peer review of the design of a storm shelter.  

Now that you have taken the exam, what will be your first project involving a storm shelter?

Likely, it will be the Hopkins County Community Safe Room in northeast Texas with DRG Architects. Hopkins County is located in the 250 MPH design wind speed zone for tornadoes, the highest category.

Which of your projects have included a tornado shelter?

H.S. Thompson Elementary School and H.I. Holland Elementary School both in Dallas ISD.

H.S. Thompson Elementary School’s storm shelter was designed using the ICC 500/NSSA Standard for Design and Construction of Storm Shelters with design wind speeds of 250 mph, the highest category and a minimum of 100 psf roof live load. The storm shelter is located inside the two-story building, therefore, collapse loading was also considered in the design criteria. The roof system consists of wide flange beams and girders supported on steel columns designed for significant wind uplift pressures. The concrete slab on the steel framing is a composite concrete deck with headed studs. The concrete slabs on steel deck require significant reinforcement to resist uplift forces and diaphragm chord forces. The exterior walls are 12-inch fully grouted reinforced load bearing CMU which serve a dual purpose as both gravity-bearing and lateral load-resisting walls.

H.I. Holland Elementary School’s storm shelter was designed using the ICC 500/NSSA Standard for Design and Construction of Storm Shelters with design wind speeds of 250 mph, the highest category and a minimum of 100 psf roof live load. The roof system consists of wide flange beams and girders designed for significant wind uplift pressures. The concrete slab on the steel framing is a composite concrete deck with headed studs. The concrete slabs on steel deck require significant reinforcement to resist uplift forces and diaphragm chord forces. The interior and exterior walls are 12-inch fully grouted reinforced load bearing CMU which serve a dual purpose as both gravity-bearing and lateral load-resisting walls.

With IES’s extensive work in the first tier of Texas counties along the gulf coast, what projects have involved a hurricane shelter?

In 2014, IES was the structural engineer for two gymnasiums at Kingsville ISD High School. These two gymnasiums served a dual purpose. Day to day, they are venues for high school basketball, volleyball, and other athletics. However, when a storm is approaching, they give refuge to Kingsville residents. Designed as FEMA and ICC-500 compliant public hurricane shelters, these structures are able to withstand windborne debris, providing a protective layer that prevents penetration from outside objects. The structures also withstand sustained wind speeds up to 200 mph. Sufficient open space is provided, inside, for sheltering as many people as possible while providing emergency power, adequate ventilation, and restroom facilities to be able to wait out the hurricane. Built as domes, these structures utilize CMU load bearing walls and a concrete shell clear spanning 160 feet.

To learn more about IES’s experience on projects requiring special inspections of impact-protective systems or storm shelter experience please don’t hesitate to reach out to our offices.