COLLAPSE:MOVEMENT OF THE STRUCTURE

We have been discussing the dangers of the collapse of fire buildings and how the collapse relates to time. We will go there again in the near future. Now, we will talk about the “big ones”-the indicators that alter your plans in a moment.

Some of the signs are in the hands of the incident commander outside the structure, his staff, and the newest eyes and ears outside the building-the RIT teams (or whatever acronym you use to describe them).

Other signs are the responsibility of everyone inside the building. The only thing is that this time all members of the fire forces on-scene should be on the same page, “Recognizing Collapse Indicators,” and its sequel, “What To Do About It!”

What do you see? This is the first indicator for arriving people. Among the signs you may notice are the following: Where is the fire? How much of the building appears to be directly affected by fire spread? How violent is the fire in your mind’s experience? Fast burning, blow-torch-type flames or heavy, pressured black smoke indicates a fierce, well-fueled (perhaps liquid fuel) fire that will “eat” the support of the building faster than ordinary and routine fires.

Is the building maintaining its original geometric shape? Has it begun leaning? Are the openings in the façade looking a little “soft”? Glance at the parapet. Is it leaning toward the sidewalk (normal failure) or toward the roof (rare, but more dangerous, because this collapse begets collapse of additional portions of the structure)?

There, you have done a major size-up-and in only a second as you dash toward the entrance of the building. Remember, you are also looking for indications of fire location, people seen and suspected, alternate entry and exit availability (roofs, outside windows, fire escapes, portable ladders already in place-a great item for RIT teams to have on its checklist).

Now, what are those few things to us? Collapse indicators! Heavy fire could mean fire on more than one floor, openings in structural supports for humans-floors and stair treads. At least, it means move more slowly, if at all.

Building movement.

Over time, a building gets tired and has some “romantic movement” to it that was never designed into it. But, if it is moving because of different coefficients of expansion of dissimilar materials used in construction as they are exposed to heat, it is a major collapse indicator. We will return to this later.

If the change is because a two-story frame building is leaning in from the second floor level, it is a demand to shift strategy. Frame buildings collapse with very little warning and usually fold at the different floor levels-at least those of platform construction.

Now, the troops are on the inside operating. What are the danger signs for which Command is responsible? All of the above and more!

Moving cracks in the structure.

It is an ongoing challenge to find a crack or to ensure that one is not beginning. Remember, all masonry and brick buildings have cracks-virtually right after construction. That is not what I am talking about! A moving crack is of such paramount importance that it should create a Mayday situation for the inside teams. “Cracks in building walls are hard to see!” one firefighter told me. “Well, Pilgrim,” I answered, “look at the building. Do you see smoke coming through the bricks or the wood sheathing? Do you see water seeping from a blank wall? Well, that is telling you that there is an opening from the inside of the building to where you are on the outside.”

The action to take here is to record it and report it to everyone. Get additional information from around the structure and from inside. You at least must monitor this opening. If it gets worse, get the crews out!

Wall bulges.

You usually see bulges in one-, two-, and three-story brick buildings. Most times, it means that the steel supports for the roof rafters or the floor joists are moving. Remember, the steel support must move eight inches every 100 feet of length when it is heated to 600 or 700 degrees. The bulge is caused by the bricks’ being pushed out from the movement. If the masonry is very strong, the steel beam will find its additional length by twisting and expanding. The trouble here is that it will drop its load of bearing lumber or trussing to the floor below.

This condition cannot be seen from the command post. You must dispatch an assistant to the corner of the structure to look along the plane of the suspected wall from time to time-at least until the fire looks as though it’s under control. The firefighter assigned to do this should be instructed to watch also for the “plumb” of the wall. Remember, a vertical wall is only strong if the load it carries is at right angles to it and to the ground that supports it. As the wall bends, bulges, leans-or what have you-the load becomes eccentric and can no longer be counted on to support anything. Get the firefighter out!

The key to successfully detecting an impending building collapse on the fireground is to make sure everyone is capable of recognizing the signs and reports them to the decision maker. You do that with haz mat and EMS. Why not put the same emphasis on recognizing an impending collapse? Collapse is killing us for sure! More next time.

TOM BRENNAN has more than 35 years of fire service experience. His career spans more than 20 years with the Fire Department of New York as well as four years as chief of the Waterbury (CT) Fire Department. He was the editor of Fire Engineering for eight years and currently is a technical editor. He is co-editor of The Fire Chief’s Handbook, Fifth Edition (Fire Engineering Books, 1995). He is the recipient of the 1998 Fire Engineering Lifetime Achievement Award. Brennan is featured in the video Brennan and Bruno Unplugged (Fire Engineering/FDIC, 1999).

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