I'd like to build a small wooden platform for use in a scaffolding tower. It
will be a mixture of plywood and planed timber. I will be standing on it, so
I want to make sure it's strong enough.

Rather than following my usual approach of using great big bits of wood,
which has been 100% successful in the past, I'd like to try to calculate the
sizes of the bits of wood required. Websites such as
http://www.forestryforum.com/members...eamclcNDS2.htm answers some of
questions, but I'd like to learn how an engineer would approach this. I
realise this will involve some maths.

Can anyone recommend some websites or traditional paper books I could look
at?

I don't know how in depth you want to be, or the strength of you maths
skills - but I've been very happy with Kermani's - Structural Timber
Design.

It's aimed at professional engineers so it assumes reasonable algebra
and trig.

http://www.amazon.co.uk/Structural-T...2930999&sr=8-1

wrote in message
...
I don't know how in depth you want to be, or the strength of you maths
skills - but I've been very happy with Kermani's - Structural Timber
Design.

It's aimed at professional engineers so it assumes reasonable algebra
and trig.


http://www.amazon.co.uk/Structural-T...2930999&sr=8-1

Thanks, that's probably the sort of thing I'm looking for. I don't mind
trig. and a bit of calculus. Would it cover fairly simple cases like a sheet
of plywood supported along 2 edges and with a load in the centre, as well as
the more complex structures shown on the cover? I reckon at present I'm
designing stuff in the same way as a novice medieval carpenter would, and
I'd like to learn about some of the stuff that's been discovered since then.

Sorry - I linked to the newer, more expensive book by Kermani - this
is the one I have:

http://www.amazon.co.uk/Structural-T...2999600&sr=1-6

The sheet of ply could (probably) be treated as a simple beam
supported at both ends with a point load - assuming it's much longer
than wider. If it is wide enough to be distorting both between the
supports and across its width, a more sophisticated treatment might be
necessary - not sure about that one.

The book linked to above has lots of worked examples and tables of
typical performance characteristics. These were the most useful things
about the book to me - along with explaining standard correction
factors (I values) used by structural engineers).

If you buy the newer, more expensive book - be sure to post a review.

On 9 Jun, 20:33, " wrote:
Sorry - I linked to the newer, more expensive book by Kermani - this
is the one I have:

http://www.amazon.co.uk/Structural-T...ani/dp/0632050...

The sheet of ply could (probably) be treated as a simple beam
supported at both ends with a point load - assuming it's much longer
than wider. If it is wide enough to be distorting both between the
supports and across its width, a more sophisticated treatment might be
necessary - not sure about that one.

The book linked to above has lots of worked examples and tables of
typical performance characteristics. These were the most useful things
about the book to me - along with explaining standard correction
factors (I values) used by structural engineers).

If you buy the newer, more expensive book - be sure to post a review.

Dear Simon
I have a timber engineering degree from IC. I was a biochemist at the
time and only signed on to remain in statute pupilare for sporting
reasons in 1975/6 but it was the most intersting degree I have done.
It did teach me that unless you are pretty proficient at maths you are
wasting your time trying to design anything from first principles but
instead just use some of the many tables available.
You do not state what your objectives are within your overall
objective. Is it to get the slimmest beam possible or the strongest
one for a certain size etc etc. It is not appropriate to treat ply as
a simple beam as the product is anisotropic and obviously desinged to
be so. If, hypothetically, you treat it as a beam then you need to
ensure that the comrpession and tension zones actually have the fibres
in the line of the beam and in tension at the bottom and compession at
the top! Also most of the "strength" of the beam comes from the
separation of these two zones (look at the formula for a beam and work
it out) ie the "depth" of the "joist", so even 1" ply will not span
much! It would be more elegant to use 4mm ply glued and stapled to two
2" battens top and bottm to make an I beam as per the manufactured
beams using this principle. It is is ply that you need to use for the
platform then it will need stiffening under with mini joists suitably
fixed.
My suggestion is to find out the span, work out the maximum load you
are likley to need in mid span (? pile of bricks, mortar and tools
plus a fat contoller telling you what to do (smile) ) and then use the
strongest material you can to make it as small as possible. this is
likely to be a platform of high grade ply surmounted and glued and
screwed to a very strong timber such as greenheart.
Is it really worth it? Why not just make a bigger softwood beam on
shuttering ply?
Chris G