From the FCFD’s PIO office – “Fairfax County Fire and Rescue Department units responded to a commercial fire at approximately 8:10 a.m., Sunday, December 2, 2007, in the Springfield area of Fairfax County. The commercial building, a warehouse, is located at 7390 Ward Park Lane.Firefighters reported heavy fire from the front with flames rising more than 50 feet above the roofline of the two-story, 100 by 300 foot warehouse. The warehouse was fully involved with fire causing firefighters to fight the fire from the exterior. The fire was brought under control in approximately 90 minutes. Subsequently, a third alarm was requested bringing over 90 emergency personnel to the scene. There were no reported injuries. The warehouse stored coffee products and housed a woodworking business.
Damage is estimated at $3.7 million.
The cause of the fire is under investigation.”
This fire went to a 3rd alarm and it was a defensive operation with the use of multiple heavy-caliber streams.
One of the issues at that fire was that of a partial collapse. The building being a warehouse type of occupancy is of Type II construction. This type involves the use of non-combustible structural materials but those building elements are not protected as we find in Type I, Fire resistive construction.
When fire conditions are well advanced in Type II, there are a number of factors that can contribute to the failure of different structural components. Steel beams, steel bar joist, metal lintels over bay doors, columns, and exterior walls are all easily affected but in different ways.
Discuss the issues associated with building collapse and/or failure of building components and what the signs of this problem are. What steps and tactical activities do, or should, we take in addressing the issue of structural compromise?
Courtesy of Deputy Fire Chief Jeff Coffman
1 comment:
Type II (limited or non combustible) construction is quick and easy to put up, and just as quick and easy to take down by fire.
The strength and integrity of exposed, unprotected metal structural components is extremely vulnerable to heat and flame. Steel will begin to elongate (move) at 800 degrees with full potential failure at 1000 degrees. Our free burning fires routinely reach temperatures over 1000 degrees. Arriving on the scene of what's pictured, a company officer should already be thinking along the lines of collapse potential. Voicing this potential over the radio causes other's to get on the same page.
The elongating action is when steel beams and other steel structural components begin to move because of heat. This movement results in metal expansion and twisting, which causes a shift in the balance of the load being carried. Instead of load being applied in balance, it becomes more eccentric, out of balance. This movement can often be stopped if enough water is applied to cool the components. This causes the moving component to freeze in place. Regardless, any place movement has taken place is not a place for us to be.
Signs of this movement can often be identified by cracks in exterior walls, smoke under pressure pushing out of the building from what would be considered high resistance areas, like masonry walls, roofs, corner joints, etc.) You may notice broken glass in window frames, jammed doors, bulges in exterior walls, cracks, alignment issues above lintels, etc. When fire is through the roof, you can bet movement is already occurring. Sometimes you may hear the metal components making noise. Think about how your non stick pan clicks as it expands and contracts on the heating element. Now imagine this much louder. Granted there are many loud sounds on the fire ground, so don't let this be your only method for identifying structural movement, its just one to consider.
Our operations begin with preplanning. Know where this type of construction is in your area. What fire protection systems are in place that may assist with firefighting efforts? What is the size and complexity of the building layout? What is your life hazard at various times of day...8 a.m. on Sunday morning (warehouse)? What is in the building, Class A combustibles, hazmats, etc? What are your water supply considerations, available pressure, and volume from local hydrants? What are your positioning considerations?
Going in to type II construction, position from the start as if you were establishing collapse and corner safe areas. This will save you time and effort in moving apparatus if transitioning from offensive mode to defensive mode. Plus, it does not put fire personnel in harms way like trying to move this equipment in the late stages of a fire.
Big fire, big water, this was not your 1 3/4 hand line through the front door fire. This was appropriately determined a defensive attack from the start. Large caliber streams, preferably solid tips for high volume, deep penetrating streams. Direct streams to the underside of the structure and to the base fire to extinguish fire and to cool the unprotected steel. This cooling action can often stop steel movement and prevent catastrophic collapse. As well, the tar roofs often found on Type II construction have a way of generating their own fire load through metal deck fires. As the tar melts from heat and flame, flammable gases are given of that become moving fuel. The hot tar also melts and drips, often on fire starting or adding to fire below. Get Towers in position, as they provide the most versatility on defensive fires. Again, try to get streams directed into the structure from the underside, bay doors, windows, etc. This can also be done with deck guns and monitors. Remember, fire blowing from the roof area is a good thing. Let it vent when possible rather than pushing it back in with streams. The latter action can push fire deeper into the structure allowing it to spread laterally.
Because the structure is already vulnerable, consider the affects of additional water load, which will further increase the potential for collapse or may even trigger the collapse. Powerful hose streams can wash mortar from wall joints and can cause flying debris. Just because we are outside does not mean we should not still properly use our personal protective equipment. Exterior fires do not necessarily mean breathing apparatus is not needed. Think about the ill effects of Hydrogen Cyanide, which has been proven to be capable of causing ill effects on the exterior and distant from the fire scene.
Multiple water supply sources on different mains should be identified. A water supply officer should be considered.
Finally, defensive operations are situations that should continually keep you on your toes. There is so much that can go wrong and in the blink of an eye. Rarely, will you outrun an "event". Key is being in the right place at the right time. Slow your pace, this fire is not going anywhere but out, eventually. The structure is lost and a new one will likely be built. Water will damage everything the fire won't. Slow, steady, and safe operations are called for. Above all, everyone remain vigilant for signs of collapse, dangerous or unique circumstances, and don't be ashamed to speak up if you have an intuitive feeling about something. Consider multiple Safety Officers depending on the size and complexity of the structure.
Be Safe!
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