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Re: cantilever T-beam

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I was thinking only of a cantilever because the previous writer was proposing to use K = 2. As for your example, I often run into that on overhead cranes with walkways. I often use the guard-rail as an auxiliary truss, if I don't want to, or can't, cantilever off the bridge girder. The customer says "what in H" is that HSS 8x4 or whatever top rail on the guard rail. Fortunately, sometimes I can brace back laterally to the bottom flange of the bridge girder at the centre or 1/3 points to reduce the unsupported length.

Kevin Below wrote:
Gary, does that mean that a bridge with side trusses which support the deck on the bottom member does not have a potential buckling problem of the top chords under the compression load ? Your explanation is logical, but I hadn't thought about it before. I'm thinking of a short steel footbridge I have to do soon. I was concerned about buckling of the top chord (which is also the hand-rail). On 3/29/07, * Gary L. Hodgson and Assoc.* <ghodgson(--nospam--at) <mailto:ghodgson(--nospam--at)>> wrote:

    You might look at where the load is applied on the cantilever.
    Nethercott in Britain then Galambos in the USA gave descriptions
    of the
    appropriate length factor for cantilevers.  If the load is applied
    or below the neutral axis determines whether the beam can buckle
    sideways.  For example, I get involved with a lot of crane
    runways, e.g.
    a single monorail beam cantilever,  loaded on the bottom flange,
    buckle to the side as the vertical load is counteracting the
    tendency to
    buckle sideways. Hope this helps.

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