huangyhg

metal railing and post deflection criteria
i can find no deflection criteria for metal handrail/guardrail and associated support posts. the codes all have required loadings to be resisted, but only require that the elements not be overstressed. the metal stairs manual states that deflection is important and should be considered since it goes to the "feel" of structural integrity, but gives no guidance. i may have missed it.
can anyone point me in the right direction, or offer a rule of thumb that you've used?
thanks in advance-
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i've never seen deflection criteria specified anywhere. 2l/180 (for cantilever) would be less than 1/2" for 42" highrail. for full design load, i don't think that would be too alarming (imho).
(it may be of interest to note that ibc 1607.7.1.3 allows a 1/3 stress increase for railings designed using asd)
i haven't had any complaints with handrails deflection in the past and have designed to meet the code strength requirements of 50plf or 200 pound concentrated load etc.. through pushing on handrails that are the same as the size i have come up with through using the strength requirements makes me believe there will not be a serviceability issue as long as you meet the typical strength requirements for standard post and rails.
if you can feel the handrail move at all when you push on it, the consumer confidence level drops drastically, only because he does not want to drop with the handrail.
the ewag principle is used here for the proper limitation on the tolerable deflection.
mike mccann
mccann engineering

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