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Wood I-beams

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  • Guest's Avatar
    Guest replied
    I guess it never ceases to amaze me, firehat87, about how much everyone of us needs to learn about this stuff. We all knew it was a dangerous job when we got into it, but that doesn't mean we should just accept it by going through our fire careers blindfolded and thinking "that won't happen to me". Like I have said before, preplanning is the key to keeping us as safe as we can possibly be in this job.
    Thanks for the info and I'll see what I can find out about these fiberglass I-joists.

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  • Guest's Avatar
    Guest replied
    I read something not too long ago, and it may have been by Brannigan, but it scared me. If I recall, they are now laminating wooden i-beams with fiberglass with carbon fibers in the mix. The combination of carbon and fiberglass is supposed to increase the maximum load possible on the beam by three or four times. The problem is, when it burns, the fiberglass melts away and them you just have a plain old wooden i-beam that is loaded to 400% of its max.
    Told you you'd be scared.

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  • Guest's Avatar
    Guest replied
    Mike,
    thanks for the reply and info. I just started reading the 2nd edition of Mr. Brannigan's (copyright 1982) book and will ask the Chief of my Dept. if he can get the 3rd edition for further study. I'll admit I was shocked to see some information on these things in the second edition. In my part of the country, to the best of my knowledge, the use of these in construction is new.
    Haven't heard any further in regards to what our building dept. may be able to do to keep these out the homes in our city, but I'll have to be patient. The most important thing is, we know that they are there.

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  • Guest's Avatar
    Guest replied
    This is straight from Brannigan's Building Construction for the Fire Service 3rd ED. I have taken a building constrution class which is tuaght out of this book and it is a must for any fire house to have around. It will leave you in aw. I did get to meet "the man" Mr. Brannigan for only a few minutes as he stopped by my Recruit Class about 8 months ago. Although, we did not have time to ask many question I could do nothing but thank Mr. Brannigan for what he has done for the fire service. OK

    p. 118
    Sawn wooden Beams contain excess wood which is unnecessary daed weight. A beam requires strenght in the top to resist compression and in the bottom to resist tension. All that is needed in between is a web to separate the top from the bottom. In recent years wooden I-beams have been developed which saves weight, and have other desirable construction characteristics.
    p. 551-552
    The wooden I-beam sawn out of a tree trunk is inefficient in terms of weight and cost. Recently the sawn beam has been replaced by wooden I-beams (composite wood joists).
    Look at the end of a steel I-beam. Since the steel is extruded through a die, the designer can choose the most efficient shape. Both the top flange and the bottom flange are wide to cope with compressive and tensile loads. The web, which separates the top from the bottom, is thin, just sufficient to keep the top and the bottom apart.
    A sawn wooden beam could be thought of as "containing" an I-beam with "surplus" wood along the sides. The surplus wood is what makes it possible for firefighters to stand and operate on a burning structure. This "fat" has been the basis of interior firefighting tactics. As long as only the "fat" or surplus wood is burning, a firefighter is relatively safe. Until it burns away, the beam is structurally sound. The gradual sagging of sawn beams due to the loss of exterior wood often gave warning of impending collapse.
    Wooden I-beams are another method of making buildings lighter. The beams consist of solid or laminated 2 x 4 for the top and bottom chords, and a plywood of oriented strand board (OSB) web between them. They are manufactured in lengths up to 60 feet. Contrasted with sawn beams, the "fat" or surplus (structurally unnecessary wood along the sides) is no longer present.
    The web of the I-beam is often penetrated for utilites, and in some cases sizable holes are cut into it so that any fire gets a grip on both sides of the I-beam at the same time, guaranteeing early failure.
    Often, cut-off ends of I-beams are used as "firestopping". Be alert to them.

    That there is a tid bit of what Mr. Brannigan has to say about Wooden I-beams and it is important that you continue your reasearch on the subject. I hope that what I have offered you of Mr. Brannigan's book can help. Please be safe and look out for your brothers and sisters.

    Mike Skidmore

    ------------------
    PROUD, PROFESSIONAL, PROGRESSIVE

    Montgomery County Division Of Fire/Rescue Services
    [email protected]

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  • Guest's Avatar
    Guest replied
    Thanks ChiefJTL, The city I work in is an established bedroom community and there isn't a whole lot of vacant land for developement left.(thankfully) The safety committee in our department which consists of the Fire Chief, City Manager, Union President and a member from each shift is seriously looking into what we can do to get the builders to use 2x lumber instead if it wouldn't matter in their design in regards to span. One builder stated it is going to cost him more money to use the I-joist anyway. The city manager stated he was going to meet with the cities building official and consider making ordinances requiring some kind of protection (drywall, fire treated I-joists) but I'll admit all of this is still in it's infancy. We'll have to wait and see.

    The most important thing we the fire service can do is to keep ourselves knowledgable and preplan to keep ourselves safe.

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  • Guest's Avatar
    Guest replied
    Wooden I beams that are constructed in the manner they are now pose great collapse risk to firefighters. The infamous lightweight truss gets a lot of well deserved ink because of its rapid failure. The I beam is also a killer. Look around for them and show your Troops what to look for.

    ------------------
    "Stay in the House"

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  • Guest's Avatar
    Guest replied
    Are the rest of you like me? When I hear of any kind of truss, the name Brannigan just pops up in my head. Read what he has to say and trust his advice. It has saved many of our necks.

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  • Guest's Avatar
    Guest replied
    No, but good luck. It'll take a major tragedy to get the laws/codes changed, just like it always does. Keep in mind, the almighty dollar rules. If the I=beams are cheaper, that's what'll get built.

    ------------------
    Stay Safe.
    You asked for my opinion, now you have it. It's mine and mine only. Any similarity to another opinion...living or dead...is purely coincidental.

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  • Guest's Avatar
    Guest started a topic Wood I-beams

    Wood I-beams

    New homes being built in our response area using wood I-beams instead of 2x lumber for floor joists. Nice and light for the framing crew but we all know what's going to happen when they burn! Has anyone done anything officially to prohibit the use of these or amended codes?

    [This message has been edited by ffnbs (edited September 27, 2000).]

    [This message has been edited by ffnbs (edited September 30, 2000).]

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