Building codes- maximum deflection in a beam?

Hi all,

Designing a simple foot bridge in MATLAB (uni), does anyone know what the building code for maximum allowed deflection of a beam is? Guessing it will be Length/some constant?

Not having much luck with google.

Material will be high density wood, low density wood, and structural steel (vague I know..)

Ta, Duane.

Ok found this;
http://faculty.arch.tamu.edu/anichols/index_files/courses/arch331/NS15-2beamdesign.pdf

So Im going with L/360 for now.

L/360 IIRC

HTH

OMG

Cheers mate 🙂

The ‘old’ British Standards mostly used L/360, but the Unis are all using Eurocodes now – no idea what they recommend. I don’t think UK Building Regulations (either the England & Wales version or for Scotland) cover bridges. Your link to a uni in Texas is not a good reference for UK.

L/360 will get you a reasonable answer, but if you want actual ‘building code’ rules you’ll need to do some more digging.

Timber is generally limited to 0.003 of the span with a max of 14mm which covers joists, rafters, purlins etc… to BS5268 (need to use dead and live load in deflection check).
The eurocode is different to this and has different values and takes account of long term creep effects and the like. It may be worth looking this up as it offers slightly better in depth guidance.
However, for a bridge I would limit it to a ‘sensible’ value like live load to l/360 but dead and live combined to l/250 or similar.