On the evening of Monday August 29th, 2016 in the small village of Fishkill, NY the night was lit by a massive fire at the Gap/Old Navy Distribution Center just North of Interstate 84. Firefighters first arrived at the scene shortly after 10:30 pm and continued to battle the blaze well into Tuesday morning. All together there were over 100 firefighters from more than 20 departments on hand to battle the blaze at the almost 3 million square foot campus that Gap opened up in 2000. The fire itself was in building 100 which is just under one million square feet and it could have been worse if not for the method of construction used when it was built over 15 years ago. The building was constructed utilizing the Tilt-Up methodology, a contributing factor that helped save the campus from even more damage.
Tilt-Up is a method of construction where the walls, or panels, of a building are formed and cast in concrete on a flat surface, typically the floor slab, and when cured to sufficient strength are then “tilted” into place. This type of construction has been used in many types of buildings such as but not limited to; schools, office buildings, supermarkets, churches, animal confinement and large distribution centers.
When it comes to fire resistance in concrete, there really is no true rating definition because concrete is not considered a manufactured building product for construction. This is because Tilt-Up concrete panels are unique to each project and therefore do not have consistent manufacturing guidelines. Each job is different as the panels are made local to the project with regional aggregates and varying mix designs, density, and panel thicknesses. Ultimately the fire rating comes down to the code requirements for fire resistance of concrete and masonry walls and typically lists a minimum rating of 1-4 hours. However, the panels are only a part of the whole and other factors such as joint sealants and roof assemblies are also taken into consideration when fire rating the total building envelope. Taking all these factors together we can see that a Tilt-Up concrete building, while very durable, may also have some inherent risks in the event of a fire. Both durability and danger were on display at the Gap/Old Navy Facility immediately following the blaze.
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While there was substantial damage it could have been much worse if not for the internal MFL (Maximum Foreseeable Loss) Walls which were also Tilt-Up. In large distribution warehouses this wall is designed to help contain hazards such as a fire and prevent them from spreading from one section of a building to another. This wall helped contain the fire within one quarter of the building and the exterior panels kept it within the buildings own footprint so it could not jump to another neighboring structure. However, there are dangers when battling a fire in a Tilt-Up building that must be taken into consideration for the safety of the firefighters during the fire and for the investigators afterwards. A Tilt-Up building’s walls are tied together by the steel lacing of the roof membrane and when that assembly is compromised it leaves the walls with substantially reduced support. This is what occurred at the Gap/Old Navy Facility but fortunately there were a couple of small things that helped in a big way. Concrete Strategies out of St. Louis was the Tilt-Up Contractor that did the original construction of the facility. There were techniques they used that helped keep the walls standing after the roof was burned through. First, when tying the slab back to the panels they connected floor to wall with rebar dowels that had been previously poured into the panel. This helped to give a mechanical connection at the panel base. The other common practice that Concrete Strategies utilizes is the installation of “Alignment Plates” into all their panels. These plates tie each panel to the one next to it and are used to align the panels once they are vertical. Another function of the alignment plates is that they helped keep the wall panels rigid during the fire and the entire exterior wall was still standing post fire. However, there was still the potential that the walls could fall and with an on-going investigation the Department of ATF ordered a portion of the buildings panels be pulled down so investigators could safely enter the building to do their job. Concrete Strategies was also brought in to brace the remaining panels and they in turn reached out to A.H. Harris to provide braces and helical anchors for the job. Because of the concern for the on-going stability of the walls this had to be done immediately and the panels needed to be braced over the upcoming Labor Day Weekend. Therefore Concrete Strategies sent their crew up from St. Louis on Friday and an A.H. Harris truck met them on-site Saturday morning at 7 am with braces and badgers so the job could get done quickly. The Brace Badgers were installed outside the perimeter and the braces anchored between them and the panels so that the remaining walls would no longer be in jeopardy of falling down.
In less than a week from the time of the fire the building was stabilized and the Fire Investigators and clean-up crews could do their work. Thank you to Concrete Strategies for their quick response from so far away and for thinking of A.H. Harris when it came to the Tilt-up hardware they needed to do the job.
If you want to learn more about Tilt-Up construction and its relationship to fire resistance please visit the Tilt-Up Concrete Association’s website. To hear more about the fire and subsequent building stabilization of the Gap/ Old Navy Distribution Center then plan to attend the 2017 TCA Conference next September in Miami where a full seminar will be presented by Concrete Strategies Vice President Barclay Gebel. A.H. Harris will be there and we look forward to seeing you there too!