huangyhg

balustrade and handrail loading
i would be interested in finding out peoples views on the required live loads required for balustrading. here in australia (as 1170.1) we have some quite onerous loading provisions which i am not sure always are practical or physically achievable. for example
for private dwellings (stairways, parapets and balconies)
point load = 0.6 kn inward or outward at any point on the handrail
distributed load = 0.4kn/m inward or outward along handrail
for handrails and balustardes to all roofs the distributed load is 0.75kn/m
for handrails and balustrades subjeect to crowd or "panic" loads the distributed load is 3kn/m.
another question is if you have an internal balustrade say on a stair or platform what load do you design the members/infill panels under the top rail? if it were an external balustarde the wind load would be appropriate but what about the internal scenario?
those loadings are not all that onerous. in the us, osha requires 200lbs (0.9kn) and requirements for the spacing of the rails and supports. it's not difficult to satisfy that requirement. usually a normal handrail (either wood or steel) will suffice.
as the quote (from the osha regulations) below notes, this is satisfied with 1 1/2" (38.1mm) nominal steel pipe or 2" diameter wooden rail.
29 cfr 1910.23 states
"(e)(3)(iv)
most building codes in the us distinguish between "handrails" (those rails used for support/stability when using stairs or steps) and "guardrails" (those rails used to prevent inadvertent falls for heights above about 2m). for external applications, the rail must meet 0.89kn load applied at any point and in any direction along the top rail. it must also withstand a 0.73kn/m distributed load applied in any direction at any point. these two loadings are independent and are not required to be applied simultaneously. for interior applications, the 0.73kn/m requirement is dropped, but the other remains.
most designers consider that all parts of a handrail or guardrail system must meet the same loading criteria, as these are life safety components and thus incur high liability.
guardrails have similar requirements, except that 0.73kn/m must be applied horizontally and 1.46kn/m applied vertically downward, simultaneously.
these are for other than dwelling units. for dwelling units, most designers consider the 0.89kn requirement to be adequate.
additionally, there is a restriction on the spacing between ballusters. the space must be no greater than 100mm.
ron
i would like to know how other engineers are applying the required loadings to guardrails - specifically in terms of designing the anchorage. are these loads to be considered "working", "ultimate" or something in-between? the ubc and osha do not clearly state. thank you.
that depends upon the material and the code or governing organization allowances under that material. for wood, steel, and aluminum you can still use the allowable stress methods (loads are not factored), though each has lrfd procedures in use. for concrete, allowable stress methods are typically not used anymore, due to code constraints.
so under your question, i would apply these loads, say to an aluminum handrail, as minimum working or application loads and use allowable stress design (asd)methods. this is just my preference when either is allowed.
ron
bld-engr (visitor)16 jun 02 7:59
do you know the basis for the 1.46kn/m vertically downward applied load. is there a test or other document describing the logic behind this requirement? is it to account for the tendancy for people to sit on the guardrails? please repond.

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