Anyone any good at steel beam calcs

[JimK]

Need to rebuild double garage flat roof.

Currently held up by 2 x pretty scary "home laminated" plywood nonsenses that I have propped.

Beams need to be C 6.5m depth, supporting 7ft timber cross members, supporting ply deck then butyl membrane.

What size/spec steels do I need?

If I wanted to lift out car engines with winches attached to one or other beam, would that need a different spec?

TIA

Jim K

[newshound]

Not enough information.

[Bob H]

On 01/06/2014 13:05, JimK wrote:

I used to work in the steel fabrication and erecting game for many
years, and for what you want I would say something like a 6x3 RSJ would
be fine just to hold up the roof. You would have to find the spec of 6x3
RSJ and then work out how many you would need from the area of the roof.

For lifting a car engine out with a chain lift you would need something
a 10x5 RSJ, but the sizes are all metric now, so you would just pick the
equivalent.

All the above is mostly guestimations as I don't haveenough info about
your garage roof.

[JimK]

Er... so ask away?.....

Jim K

[newshound]

On 01/06/2014 20:24, JimK wrote:
> Er... so ask away?.....
>
> Jim K
>

Well for a start, how big is the garage. What sort of engines: Fiesta or
Jaguar / Range Rover.

[JimK]

Er well it's a double garage, the depth is 6.5m as per the OP....

Engines - assume medium average weights

Jim K

[newshound]

When you are talking about beams, depth is usually the vertical
direction. OK, so your garage is 6.5 metres from front to back. What is
the dimension from side to side. Which way do you want the steel beams
to run. What sort of walls have you got to support them at each end. How
many do you expect to have. You mention 7 foot timbers in the OP. What
are their dimensions and which way do these run?

[newshound]

Oh yes, and does it have one door or two (with a brick pier in between).

[Bob Minchin]

Usual trick to avoid uprating a beam for the odd engine out point load
is to have a couple of acrow props to fit either side of the vehicle
when applying such loads.

[newshound]

Even just one side, especially if the car isn't positioned right in the
middle.

[JimK]

/ When you are talking about beams, depth is usually the vertical direction.

You were asking about the garage. I am asking about beams...


/OK, so your garage is 6.5 metres from front to back.

Correct.

/What is the dimension from side to side.

Double garage? 2 x 7ft doors etc So say 6m external side to side.

/Which way do you want the steel beams to run.

Does it matter? Front to back say

/What sort of walls have you got to support them at each end.

Brick/block

/How many do you expect to have.

As few as necessary. 2 say.

/You mention 7 foot timbers in the OP. What are their dimensions
?why?

/and which way do these run?/q

Er from the beams to the walls? a bit longer than 7ft....

Surely its the total load of the deck + snow weight that defines all this? Spread over 4 walls & 2 beams? Add snow factor on top plus allowance?

Jim K

[JimK]

Usual trick to avoid uprating a beam for the odd engine out point load
is to have a couple of acrow props to fit either side of the vehicle

when applying such loads. /q

Good idea thanks.

Jim K

[Capitol]

JimK wrote:
>
> Surely its the total load of the deck + snow weight that defines all this? Spread over 4 walls& 2 beams? Add snow factor on top plus allowance?
>
> Jim K

Er, no. You are talking about lifting out car engines using the beam.
This will drastically change the loading.
However, my garage uses an 8 x 5.5 inch beam for your span and the
ceiling joists are 5 x 2. The beam provides a king post support for the
concrete tiled roof and the deflection is less than 5mm ( probably about
2). Note that beams are specified by weight per foot/metre for a given
external size and this decides their performance. The easy way to answer
your question is to ask your local structural steel stockist, who will
know off the top of his head what you need. A car engine is unlikely to
exceed 500Kg and if this is specified as the mid point loading then you
should be OK. The distributed roof loading will not exceed 30lb per
square foot for snow conditions IMO. If you want to do it the hard way,
go to the local library and find the standard text books, which will
have worked examples to show you how to do it. Bear in mind that you
need pad stones(concrete) under the beam ends and will need at least 6
inches of support for a 5.5inch beam.

[JimK]

/> Surely its the total load of the deck + snow weight that defines all this? Spread over 4 walls& 2 beams? Add snow factor on top plus allowance?

>
> Jim K

Er, no. You are talking about lifting out car engines using the beam.
This will drastically change the loading.
However, my garage uses an 8 x 5.5 inch beam for your span and the
ceiling joists are 5 x 2. The beam provides a king post support for the
concrete tiled roof and the deflection is less than 5mm ( probably about
2). Note that beams are specified by weight per foot/metre for a giv

Snip

thanks for the info on you roof. How big is your garage?

NB you appear to have taken my perhaps simplistic summary of the overall roof loading puzzle to somehow be a justification for extra loads when lifting engines out of cars :-)

I can work around that with Bob's suggestion to acrow the beam if I ever do use it as an engine hoist.

Jim K

[Capitol]

JimK wrote:
>
> thanks for the info on you roof. How big is your garage?
>
>

About 19' x19' internally.

[Rick Hughes]

On 02/06/2014 09:01, newshound wrote:

importantly what will support beam ends ... plain wall, double thickness
piers ? How much bearing will beam have on this support (needs 150mm at
least)

--
UK SelfBuild: http://uk.groups.yahoo.com/group/UK_Selfbuild/

[Rick Hughes]

6"x3" with a 6.5m span ... and could have a central point load of
~750Kg for an engine ... seems a small beam for that.
Wouldn't a 7"x4" (178 x 102) be a better fit ......... but I don't have
calcs to do this.

You can also find 2nd hand RSJ's in scrap yard .. just pay scrap weight.

I used 8"x4" when I needed them for a garage, to allow for lifting an
engine.

[JimK]

/ -show quotedtext -importantly what will support beam ends ... plain wall, double thickness piers ? How much bearing will beam have on this support (needs 150mm at least)/q

Indeed - they will have proper pads to bear on to proper appropriate sizes.

Jim K

[JimK]

/newshound

Not enough information./q

Do you have enough information now?

It seems to have gone a bit quiet since I replied to your last notable post...

Jim K

[The Natural Philosopher]

to get to low deflection over a flat 6 meter span you need serious wood.
I've got 12x12 oak here for that span..

Id say 7-8" deep RSJ is what you want and a crane to install it.


--
Ineptocracy

(in-ep-toc’-ra-cy) – a system of government where the least capable to
lead are elected by the least capable of producing, and where the
members of society least likely to sustain themselves or succeed, are
rewarded with goods and services paid for by the confiscated wealth of a
diminishing number of producers.

[JimK]

/ d say 7-8" deep RSJ is what you want and a crane to install it./q

A crane?! Meh he

Think of all those trendy fold away multiple French windows that fools want these days (for opening 10 days a year...) I can't see a crane being required or appropriate to install the equally long beams above them? beams that will have to take more load hence be even heavier than my rqmnts?

Nah several blokes & several milk crates....

Jim K

[Capitol]

> Nah several blokes& several milk crates....
>
> Jim K

Agreed. The last one (20') took two of us and a skate board!

[Tony Bryer]

On Tue, 03 Jun 2014 09:56:46 +0100 The Natural Philosopher wrote :
> Id say 7-8" deep RSJ is what you want and a crane to install it.

No crane necessary - 7" is 178x102x19 so for 6m about 120kg, 8" is
203x102x23, so about 140kg. Remember that with suitable temporary
rests you need only lift one end at a time so an easy 2-person
lift, one if fit.

--
Tony Bryer, Greentram: 'Software to build on',
Melbourne, Australia www.greentram.com

[Rod Speed]

JimK <jk98...@gmail.com> wrote

I did mine with some sheerlegs and a boat winch.

Worked fine.

[JimK]

Aha just the man!

Care to give us a demo of superbeam to guide my garage re-roof plse? :>)

Others who offered seem preoccupied currently...

Details upthread....

Cheers
Jim K

[newshound]

I've done my bit in getting to a "spec" where sensible responses can be
posted.

Not getting at you personally, but a lot of posters looking for help
fail to give even the most basic detail.

If you want advice on snow loading you had better tell us where you are.

[JimK]

On Tuesday, 3 June 2014 12:56:49 UTC+1, newshound wrote:
> On 03/06/2014 09:43, JimK wrote:
>
> > /newshound
>
> >
>
> > Not enough information./q
>
> >
>
> > Do you have enough information now?
>
> >
>
> > It seems to have gone a bit quiet since I replied to your last notable post...
>
> >
>
> > Jim K
>
> >
>
> I've done my bit in getting to a "spec" where sensible responses can be
> posted.
>

pfft! can't or won't?

;>)

Jim K

[Tony Bryer]

On Tue, 3 Jun 2014 04:27:17 -0700 (PDT) JimK wrote :
>
> Aha just the man!
>
> Care to give us a demo of superbeam to guide my garage re-roof plse? :>)
>
> Others who offered seem preoccupied currently...
>
> Details upthread....
>
> Cheers
> Jim K

Assuming 6.5m span and beam taking half of 6m span flat roof, gives a roof
load of say 3.75kN/m plus an engine load at centre of 500kg/5kN, assuming
an unrestrained beam you'd be looking at a 254x146x37 but if the beam can
be considered to be restrained - not unreasonable if joists cross beam and
there is some form of blocking or runners either side of the top flange a
203x133x25 would be ok: decent margin strength-wise but deflection (26mm)
probably as large as you'd want to go - though remember this assumes full
snow load and engine and most of the time neither of these will be applied.

But this isn't advice - if in doubt you need advice from someone who has
seen the job or at least a plan.

[JimK]

Thanks for the advice Tony - understood.

Currently over the 6m width there are two 6.5m span poorly plywood "beams" in there - well propped up...

First at ~2.4m in, then another at ~4.8m (then 1.2m to the other side wall)

I was thinking to replace with steels and rebuild/repair the flat roof on top... presumably that would change things re steel specs?

(ALternative would be to run 6m span at 90degrees to existing but would be more work)

Thanks again

Cheers
Jim K