Balustrade solid rod infill justification

[Martin.H]

UK loading codes require that a point load is applied to a balustrade infill.

The use of vertically spanning smallish diameter steel rods (say 12mm dia.) is common for balustrade infill, but justifying these to resist the required point load via. bending action isn't possible. I'm sure in testing they can be justified as in reality there is some catenary action going on.

Does anyone know of:

A) a calculation method to justify rods, or
B) another method (test data, published guidance etc)?

Much obliged.

Martin.

 

[XR250]

In the US, it is a load over a 1 sq. ft. area. Sounds like it is different overseas?

 

[Martin.H]

Yes, BS 6180:2011 states a 'point load' to be applied.

It gives no area over which that should be applied. I've taken a view and assumed it's resisted by 3 infill rods, which I think is reasonable (infill rods are at less than 100mm c/c, so that's a max load width of 200mm to hit 3 rods, which is within your 1 sq. ft. area which gives me a sense of comfort and a sense check).

I've read elsewhere on the internet that PL is applied over a 50 x 50mm area, but no reference was given so I've chosen to ignore that!

Martin.

 

[NalaCap0ne]

Hey OP. The 50mm x 50mm area is from BS 6399 Part 1. Section 5.1.3 - Concentrated Loads, states:

"Concentrated loads should be assumed to act at points on the member to give the greatest moment, shear (or where critical, deflection). Concentrated loads should be applied to individual members and assumed to act on them unless there is evidence that adequate interaction exists to ensure that the load can be shared or spread.

When used for the calculation of local effects such as crushing and punching, the concentrated loads should be assumed to act at a position and over an area of application appropriate to their cause. Where this cannot be foreseen, a square contact area with a 50 mm side should be assumed."

While this standard has obviously been superseded by the Eurocode, the 50mm x 50mm dimension seems to still pop up everywhere. I work in the facade industry in the UK, and we've found that the 50mm x 50mm area is pretty excessive, and often results in failures...so we tend to use 100mm x 100mm. There's really no source for this other than BS EN 13830 which states:

"Horizontal point load for local verification applied under the sill height on a square surface of 100x100 mm at the worst place."

However, this standard is specific to Curtain Walling, but its something......

Hope this helps!

 

[Martin.H]

Thanks, NalaCap0ne.

That's useful to know where the 50 x 50 comes from, and good to get the additional info, even if not directly related, it all helps.

Martin.