I have just exposed the existing RSJs to which new load is to be
applied to support my roof.
The BCO said the bearings may need to be exposed but has said nothing
more. For peace of mind I
probably need a structural engineer to check things, but can anyone
give a rough feel for the loadings here ?

Old fashioned RSJ, width 125mm, height 150mm, flange thickness 10mm at
the edges, 15mm at the web,
web thickness 10mm. Span is 2800mm. Can anyone tell me what type of
loads this beam can take (assuming bearings are OK). Also, what type
of point load could it take near the middle of the span ?

Thanks,
Simon.

sm_jamieson wrote:
I have just exposed the existing RSJs to which new load is to be
applied to support my roof.
The BCO said the bearings may need to be exposed but has said nothing
more. For peace of mind I
probably need a structural engineer to check things, but can anyone
give a rough feel for the loadings here ?

Old fashioned RSJ, width 125mm, height 150mm, flange thickness 10mm at
the edges, 15mm at the web,
web thickness 10mm. Span is 2800mm. Can anyone tell me what type of
loads this beam can take (assuming bearings are OK). Also, what type
of point load could it take near the middle of the span ?

Thanks,
Simon.

Provided it's not rusty and full of holes - it will more than do the job. I
have seen one half that size (height and width) and around 10 foot long
holding up two bedroom floors.

This was part of an old miners diy job when he knocked two rooms into one -
and when I asked if it would take the weight, he said that if that girder
was strong enough to hold the pit roof up, it'll certainly hold the bedroom
floors, even when I'm f*****g my wife (a very true tale by the way, those
Yorkies were tough then). LOL

On 11 Aug, 22:55, "Unbeliever" wrote:
sm_jamieson wrote:
I have just exposed the existing RSJs to which new load is to be
applied to support my roof.
The BCO said the bearings may need to be exposed but has said nothing
more. For peace of mind I
probably need a structural engineer to check things, but can anyone
give a rough feel for the loadings here ?

Old fashioned RSJ, width 125mm, height 150mm, flange thickness 10mm at
the edges, 15mm at the web,
web thickness 10mm. Span is 2800mm. Can anyone tell me what type of
loads this beam can take (assuming bearings are OK). Also, what type
of point load could it take near the middle of the span ?

Thanks,
Simon.

Provided it's not rusty and full of holes - it will more than do the job. *I
have seen one half that size (height and width) and around 10 foot long
holding up two bedroom floors.

This was part of an old miners diy job when he knocked two rooms into one -
and when I asked if it would take the weight, he said that if that girder
was strong enough to hold the pit roof up, it'll certainly hold the bedroom
floors, even when I'm f*****g my wife (a very true tale by the way, those
Yorkies were tough then). LOL

Nice story ;-)
A very fine dusting of rust on the surface, overall seems very sound.
Trouble is, there may need to be almost a point load of 250kg on it
near the middle, but
I can add some support from a new wall that runs right under it.
I've got my first kiddy on the way and its making me a bit paranoid
about safety !
Simon.

Simon wrote:
On 11 Aug, 22:55, "Unbeliever" wrote:
sm_jamieson wrote:
I have just exposed the existing RSJs to which new load is to be
applied to support my roof.
The BCO said the bearings may need to be exposed but has said
nothing more. For peace of mind I
probably need a structural engineer to check things, but can anyone
give a rough feel for the loadings here ?

Old fashioned RSJ, width 125mm, height 150mm, flange thickness 10mm
at the edges, 15mm at the web,
web thickness 10mm. Span is 2800mm. Can anyone tell me what type of
loads this beam can take (assuming bearings are OK). Also, what type
of point load could it take near the middle of the span ?

Thanks,
Simon.

Provided it's not rusty and full of holes - it will more than do the
job. I have seen one half that size (height and width) and around 10
foot long holding up two bedroom floors.

This was part of an old miners diy job when he knocked two rooms
into one - and when I asked if it would take the weight, he said
that if that girder was strong enough to hold the pit roof up, it'll
certainly hold the bedroom floors, even when I'm f*****g my wife (a
very true tale by the way, those Yorkies were tough then). LOL

Nice story ;-)
A very fine dusting of rust on the surface, overall seems very sound.
Trouble is, there may need to be almost a point load of 250kg on it
near the middle, but
I can add some support from a new wall that runs right under it.
I've got my first kiddy on the way and its making me a bit paranoid
about safety !
Simon.

Simon,

Believe it or not, that story really is true and it took place around 1988 -
and that girder (a couple of straightened out pit rings with a couple of
bolted on fish plates either side) is still there holding up those floors
with nary a sag), and I still say that's a bloody miracle.

As for you job, even without structural calcs, (and I have long forgotten
the 'bending moment' formula) that RSJ will hold whatever you can throw at
it with a standard roof - and there's no need for "parania".

Simon wrote:
On 11 Aug, 22:55, "Unbeliever" wrote:
sm_jamieson wrote:
I have just exposed the existing RSJs to which new load is to be
applied to support my roof.
The BCO said the bearings may need to be exposed but has said nothing
more. For peace of mind I
probably need a structural engineer to check things, but can anyone
give a rough feel for the loadings here ?
Old fashioned RSJ, width 125mm, height 150mm, flange thickness 10mm at
the edges, 15mm at the web,
web thickness 10mm. Span is 2800mm. Can anyone tell me what type of
loads this beam can take (assuming bearings are OK). Also, what type
of point load could it take near the middle of the span ?
Thanks,
Simon.
Provided it's not rusty and full of holes - it will more than do the job. I
have seen one half that size (height and width) and around 10 foot long
holding up two bedroom floors.

This was part of an old miners diy job when he knocked two rooms into one -
and when I asked if it would take the weight, he said that if that girder
was strong enough to hold the pit roof up, it'll certainly hold the bedroom
floors, even when I'm f*****g my wife (a very true tale by the way, those
Yorkies were tough then). LOL

Nice story ;-)
A very fine dusting of rust on the surface, overall seems very sound.
Trouble is, there may need to be almost a point load of 250kg on it
near the middle, but
I can add some support from a new wall that runs right under it.
I've got my first kiddy on the way and its making me a bit paranoid
about safety !

You could grab the demo version of super beam and have a play:

http://www.superbeam.co.uk/sbwdemo.htm

This will let you do structural calcs for all sorts of beams. Obviously
you need to know what anticipated loads to feed in to get sensible answers!



--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Trouble is, there may need to be almost a point
load of 250kg on it near the middle

Mmmm.... 150mm height, 15mm web, 250kg...
.... equivalent to 2 rather large people
.... equivalent to another largish RSJ sitting on it
.... equivalent to 0.3m wide crap upstairs block wall

I think the RSJ is likely to say "that all you got" :-)

The BCO is more interested in the bearings.
That is, crumbly crap mortar vs tightly packed slate or padstone.

sm_jamieson wrote:
I have just exposed the existing RSJs to which new load is to be
applied to support my roof.

We would need more detail of the roof construction...

Clay tiles are about 0.77 kN/m^2 for example.

The BCO said the bearings may need to be exposed but has said nothing
more. For peace of mind I
probably need a structural engineer to check things, but can anyone
give a rough feel for the loadings here ?

Old fashioned RSJ, width 125mm, height 150mm, flange thickness 10mm at
the edges, 15mm at the web,
web thickness 10mm. Span is 2800mm. Can anyone tell me what type of
loads this beam can take (assuming bearings are OK). Also, what type
of point load could it take near the middle of the span ?

Quite substantial!

I had a little play in SB4, and assuming I selected the appropriate beam
(i.e. please don't take my word for it - try it yourself!), it looks
like it would cope with a point load of just over 57kN in the middle of
the span!


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

"John Rumm" wrote in message
o.uk...
sm_jamieson wrote:
I have just exposed the existing RSJs to which new load is to be
applied to support my roof.

We would need more detail of the roof construction...

Clay tiles are about 0.77 kN/m^2 for example.

The BCO said the bearings may need to be exposed but has said nothing
more. For peace of mind I
probably need a structural engineer to check things, but can anyone
give a rough feel for the loadings here ?

Old fashioned RSJ, width 125mm, height 150mm, flange thickness 10mm at
the edges, 15mm at the web,
web thickness 10mm. Span is 2800mm. Can anyone tell me what type of
loads this beam can take (assuming bearings are OK). Also, what type
of point load could it take near the middle of the span ?

Quite substantial!

I had a little play in SB4, and assuming I selected the appropriate beam
(i.e. please don't take my word for it - try it yourself!), it looks
like it would cope with a point load of just over 57kN in the middle of
the span!

Cheers,

John.


Also taking in snow weight and high wind loading, in both pull and push
directions, your calculations would drop that figure to around 49 - 50 kN in
the centre. But it isn't so much the RSJ itself that needs calculating.
The RSJ is only as strong as the platforms it rests on. If the existing
wall pads are crumbling and dried out, then they may cause slip or sag to
the ends of the beam. This is not a good thing to have, under any loading
circumstances.

Also, Fire regulation now say that the steel must have a minimum of three
hour protection from direct heat along the full length of any structural
works. So allow for the BCO to add that equation once the works have begun.
Each Building Control Person seems to have their own particular way to
create an adequate heat barrier on these things, so ask them first about
this, before getting pads and other things done.

BigWallop wrote:
"John Rumm" wrote in message
o.uk...
sm_jamieson wrote:
I have just exposed the existing RSJs to which new load is to be
applied to support my roof.
We would need more detail of the roof construction...

Clay tiles are about 0.77 kN/m^2 for example.

The BCO said the bearings may need to be exposed but has said nothing
more. For peace of mind I
probably need a structural engineer to check things, but can anyone
give a rough feel for the loadings here ?

Old fashioned RSJ, width 125mm, height 150mm, flange thickness 10mm at
the edges, 15mm at the web,
web thickness 10mm. Span is 2800mm. Can anyone tell me what type of
loads this beam can take (assuming bearings are OK). Also, what type
of point load could it take near the middle of the span ?
Quite substantial!

I had a little play in SB4, and assuming I selected the appropriate beam
(i.e. please don't take my word for it - try it yourself!), it looks
like it would cope with a point load of just over 57kN in the middle of
the span!

Cheers,

John.


Also taking in snow weight and high wind loading, in both pull and push
directions, your calculations would drop that figure to around 49 - 50 kN in
the centre. But it isn't so much the RSJ itself that needs calculating.
The RSJ is only as strong as the platforms it rests on. If the existing
wall pads are crumbling and dried out, then they may cause slip or sag to
the ends of the beam. This is not a good thing to have, under any loading
circumstances.

The loading it can take is what it can take - that obviously needs to
include static, live, and wind etc. loads. The thrust of what I was
saying however is that there is a fair chance this steel is more than
"adequate"!

Also, Fire regulation now say that the steel must have a minimum of three
hour protection from direct heat along the full length of any structural
works. So allow for the BCO to add that equation once the works have begun.
Each Building Control Person seems to have their own particular way to
create an adequate heat barrier on these things, so ask them first about
this, before getting pads and other things done.

Three hours seems like quite a lot in a domestic situation. Do you have
a reference to the relevant section of the ADs?



--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 12 Aug, 04:20, John Rumm wrote:
BigWallop wrote:
"John Rumm" wrote in message
news:QrSdnTLLy_Ecmx_XnZ2dnUVZ8sqdnZ2d@brightview. co.uk...
sm_jamieson wrote:
I have just exposed the existing RSJs to which new load is to be
applied to support my roof.
We would need more detail of the roof construction...

Clay tiles are about 0.77 kN/m^2 for example.

The BCO said the bearings may need to be exposed but has said nothing
more. For peace of mind I
probably need a structural engineer to check things, but can anyone
give a rough feel for the loadings here ?

Old fashioned RSJ, width 125mm, height 150mm, flange thickness 10mm at
the edges, 15mm at the web,
web thickness 10mm. Span is 2800mm. Can anyone tell me what type of
loads this beam can take (assuming bearings are OK). Also, what type
of point load could it take near the middle of the span ?
Quite substantial!

I had a little play in SB4, and assuming I selected the appropriate beam
(i.e. please don't take my word for it - try it yourself!), it looks
like it would cope with a point load of just over 57kN in the middle of
the span!

Cheers,

John.

Also taking in snow weight and high wind loading, in both pull and push
directions, your calculations would drop that figure to around 49 - 50 kN in
the centre. *But it isn't so much the RSJ itself that needs calculating.
The RSJ is only as strong as the platforms it rests on. *If the existing
wall pads are crumbling and dried out, then they may cause slip or sag to
the ends of the beam. *This is not a good thing to have, under any loading
circumstances.

The loading it can take is what it can take - that obviously needs to
include static, live, and wind etc. loads. The thrust of what I was
saying however is that there is a fair chance this steel is more than
"adequate"!

Also, *Fire regulation now say that the steel must have a minimum of three
hour protection from direct heat along the full length of any structural
works. *So allow for the BCO to add that equation once the works have begun.
Each Building Control Person seems to have their own particular way to
create an adequate heat barrier on these things, so ask them first about
this, before getting pads and other things done.

Three hours seems like quite a lot in a domestic situation. Do you have
a reference to the relevant section of the ADs?

--
Thanks guys. The roof dead load is 1 tonne (very close to), including
snow load is 3 tonnes (roof is quite shallow). Roof is bearing on
several purlins such that each purlin end is carrying just over 200kg,
including snow load.
I can add an extra support under the RSJ, reducing span to about 1.8
metres (aircrete loadbearing wall passes under, whereI could easily
add a padstone - replace an aircrete block with 7N block). The bearing
I can see on one end looks like the RSJ is dry on a thick quarry tile
bedded on strong cement mortar (most of house is lime mortar), and I
assume all bearing are around 4" (t'other end must be, its in a 9"
wall).
To check the bearings properly you'd need to remove a brick next to it
and have a look.

Other issue is how to support the purlin on the RSJ. RSJ is inset
against 9" wall above it by 2". FIrst row of bricks on RSJ are dry
laid headers (2" overhang off RSJ), don't think it would be wise to
bear a masonry hanger direct on one of these.
I could drill the RSJ and bolt timber bearer and use a jiffy hanger,
but I'm not sure how drilling some 10mm holes through the RSJ affects
it, or how hanging weight off only one side could unbalance it.
When I say I'm not sure about all this, I could make a educated guess,
but a struct eng could insure it !
Simon.

On 12 Aug, 08:37, Simon wrote:
On 12 Aug, 04:20, John Rumm wrote:

BigWallop wrote:
"John Rumm" wrote in message
news:QrSdnTLLy_Ecmx_XnZ2dnUVZ8sqdnZ2d@brightview. co.uk...
sm_jamieson wrote:
I have just exposed the existing RSJs to which new load is to be
applied to support my roof.
We would need more detail of the roof construction...

Clay tiles are about 0.77 kN/m^2 for example.

The BCO said the bearings may need to be exposed but has said nothing
more. For peace of mind I
probably need a structural engineer to check things, but can anyone
give a rough feel for the loadings here ?

Old fashioned RSJ, width 125mm, height 150mm, flange thickness 10mm at
the edges, 15mm at the web,
web thickness 10mm. Span is 2800mm. Can anyone tell me what type of
loads this beam can take (assuming bearings are OK). Also, what type
of point load could it take near the middle of the span ?
Quite substantial!

I had a little play in SB4, and assuming I selected the appropriate beam
(i.e. please don't take my word for it - try it yourself!), it looks
like it would cope with a point load of just over 57kN in the middle of
the span!

Cheers,

John.

Also taking in snow weight and high wind loading, in both pull and push
directions, your calculations would drop that figure to around 49 - 50 kN in
the centre. *But it isn't so much the RSJ itself that needs calculating.
The RSJ is only as strong as the platforms it rests on. *If the existing
wall pads are crumbling and dried out, then they may cause slip or sag to
the ends of the beam. *This is not a good thing to have, under any loading
circumstances.

The loading it can take is what it can take - that obviously needs to
include static, live, and wind etc. loads. The thrust of what I was
saying however is that there is a fair chance this steel is more than
"adequate"!

Also, *Fire regulation now say that the steel must have a minimum of three
hour protection from direct heat along the full length of any structural
works. *So allow for the BCO to add that equation once the works have begun.
Each Building Control Person seems to have their own particular way to
create an adequate heat barrier on these things, so ask them first about
this, before getting pads and other things done.

Three hours seems like quite a lot in a domestic situation. Do you have
a reference to the relevant section of the ADs?

--

Thanks guys. The roof dead load is 1 tonne (very close to), including
snow load is 3 tonnes (roof is quite shallow). Roof is bearing on
several purlins such that each purlin end is carrying just over 200kg,
including snow load.
I can add an extra support under the RSJ, reducing span to about 1.8
metres (aircrete loadbearing wall passes under, whereI could easily
add a padstone - replace an aircrete block with 7N block). The bearing
I can see on one end looks like the RSJ is dry on a thick quarry tile
bedded on strong cement mortar (most of house is lime mortar), and I
assume all bearing are around 4" (t'other end must be, its in a 9"
wall).
To check the bearings properly you'd need to remove a brick next to it
and have a look.

Other issue is how to support the purlin on the RSJ. RSJ is inset
against 9" wall above it by 2". FIrst row of bricks on RSJ are dry
laid headers (2" overhang off RSJ), don't think it would be wise to
bear a masonry hanger direct on one of these.
I could drill the RSJ and bolt timber bearer and use a jiffy hanger,
but I'm not sure how drilling some 10mm holes through the RSJ affects
it, or how hanging weight off only one side could unbalance it.
When I say I'm not sure about all this, I could make a educated guess,
but a struct eng could insure it !
Simon.

Well, the struct eng that validated my roof design says they would
want 150+vat for a site visit to confirm some drawings I do for them
and to check end bearings etc, then about 105+vat for calcs to confirm
and also design an acceptable way to hang a purlin from an existing
RSJ. Does that seem reasonable ?
Question is - do I bother ?
Only thing as regards purlin on RSJ, is its loading on one side that
could try to twist the RSJ. I'm sure I'd get away with just doing it,
but for insurance purposes, etc it may be a good idea.
Simon.

In an earlier contribution to this discussion,
sm_jamieson wrote:

I have just exposed the existing RSJs to which new load is to be
applied to support my roof.
The BCO said the bearings may need to be exposed but has said nothing
more. For peace of mind I
probably need a structural engineer to check things, but can anyone
give a rough feel for the loadings here ?

Old fashioned RSJ, width 125mm, height 150mm, flange thickness 10mm at
the edges, 15mm at the web,
web thickness 10mm. Span is 2800mm. Can anyone tell me what type of
loads this beam can take (assuming bearings are OK). Also, what type
of point load could it take near the middle of the span ?


I can't answer your question numerically - but, in a domestic situation,
you're unlikely to be able to throw anything at that RSJ which it *can't*
support.

When I recently made some structural changes to my house, the BCO said that
as long as I used a 7x4 RSJ over a similar span to yours (ok, yours is 6x5 -
but a pretty beefy one) he would be happy because it would be sufficiently
over-engineered that there couldn't possibly be any problems. On the other
hand, if I wanted to use anything less, he would need to see calculations
done by a structural engineer.
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!

"Simon" wrote in message
...
On 12 Aug, 08:37, Simon wrote:
On 12 Aug, 04:20, John Rumm wrote:

BigWallop wrote:
snipped

Well, the struct eng that validated my roof design says they would
want 150+vat for a site visit to confirm some drawings I do for them
and to check end bearings etc, then about 105+vat for calcs to confirm
and also design an acceptable way to hang a purlin from an existing
RSJ. Does that seem reasonable ?
Question is - do I bother ?
Only thing as regards purlin on RSJ, is its loading on one side that
could try to twist the RSJ. I'm sure I'd get away with just doing it,
but for insurance purposes, etc it may be a good idea.
Simon.


It will be money well spent for the peace of mind you get with a proper job.
I'd say "go with the struct' eng" and make sure the whole thing lasts the
years you want it to.

I do the same as you. I look at it for months, then decide I can do the
work without problems, then change my mind and ask someone I know, with a
greater experience of the actual calculations, to come in and tell me I am
correct. But it seems to have been a good way of doing things, just for the
peace of mind I get knowing the work is done properly.

"John Rumm" wrote in message
o.uk...
BigWallop wrote:
"John Rumm" wrote in message
o.uk...
sm_jamieson wrote:
I have just exposed the existing RSJs to which new load is to be
applied to support my roof.
We would need more detail of the roof construction...

Clay tiles are about 0.77 kN/m^2 for example.

The BCO said the bearings may need to be exposed but has said nothing
more. For peace of mind I
probably need a structural engineer to check things, but can anyone
give a rough feel for the loadings here ?

Old fashioned RSJ, width 125mm, height 150mm, flange thickness 10mm at
the edges, 15mm at the web,
web thickness 10mm. Span is 2800mm. Can anyone tell me what type of
loads this beam can take (assuming bearings are OK). Also, what type
of point load could it take near the middle of the span ?
Quite substantial!

I had a little play in SB4, and assuming I selected the appropriate
beam
(i.e. please don't take my word for it - try it yourself!), it looks
like it would cope with a point load of just over 57kN in the middle of
the span!

Cheers,

John.


Also taking in snow weight and high wind loading, in both pull and push
directions, your calculations would drop that figure to around 49 - 50
kN in
the centre. But it isn't so much the RSJ itself that needs calculating.
The RSJ is only as strong as the platforms it rests on. If the existing
wall pads are crumbling and dried out, then they may cause slip or sag
to
the ends of the beam. This is not a good thing to have, under any
loading
circumstances.

The loading it can take is what it can take - that obviously needs to
include static, live, and wind etc. loads. The thrust of what I was
saying however is that there is a fair chance this steel is more than
"adequate"!


I was being a little bugger. Your calcs' are spot on. :-) Just added a
little bit to them. lol



Also, Fire regulation now say that the steel must have a minimum of
three
hour protection from direct heat along the full length of any structural
works. So allow for the BCO to add that equation once the works have
begun.
Each Building Control Person seems to have their own particular way to
create an adequate heat barrier on these things, so ask them first about
this, before getting pads and other things done.

Three hours seems like quite a lot in a domestic situation. Do you have
a reference to the relevant section of the ADs?

Cheers,

John.


I think the reference to the new amendum BS 476 parts 20 and 22, IIRC, give
guidance to both full steel structural builds and any internal new steel
supports testing requirements. But it is definitely somewhere in the BS 476
: 2009 book.

I' try to find it for sure, for future look ups.

On 12 Aug, 20:34, "BigWallop" wrote:
"Simon" wrote in message

...
On 12 Aug, 08:37, Simon wrote: On 12 Aug, 04:20, John Rumm wrote:

BigWallop wrote:

snipped

Well, the struct eng that validated my roof design says they would
want 150+vat for a site visit to confirm some drawings I do for them
and to check end bearings etc, then about 105+vat for calcs to confirm
and also design an acceptable way to hang a purlin from an existing
RSJ. Does that seem reasonable ?
Question is - do I bother ?
Only thing as regards purlin on RSJ, is its loading on one side that
could try to twist the RSJ. I'm sure I'd get away with just doing it,
but for insurance purposes, etc it may be a good idea.
Simon.

It will be money well spent for the peace of mind you get with a proper job.
I'd say "go with the struct' eng" and make sure the whole thing lasts the
years you want it to.

I do the same as you. *I look at it for months, then decide I can do the
work without problems, then change my mind and ask someone I know, with a
greater experience of the actual calculations, to come in and tell me I am
correct. *But it seems to have been a good way of doing things, just for the
peace of mind I get knowing the work is done properly.

I've had a look at the RSJ over the other side of the house (the
kitchen), and that is interestingly two parallel RSJs 3.5" by 7" with
similar flange and web sizes to the other 5" x 6" RSJ. I'm guessing
the parallel ones start with stretchers rather than headers.
It would be interesting to have seen these houses being built. Massive
gobs of lime mortar and beefy RSJs being thrown around everywhere
would be quite a sight !
Simon.

Simon wrote:
On 12 Aug, 20:34, "BigWallop" wrote:
"Simon" wrote in message

...
On 12 Aug, 08:37, Simon wrote: On 12 Aug,
04:20, John Rumm wrote:

BigWallop wrote:

snipped

Well, the struct eng that validated my roof design says they would
want 150+vat for a site visit to confirm some drawings I do for them
and to check end bearings etc, then about 105+vat for calcs to
confirm
and also design an acceptable way to hang a purlin from an existing
RSJ. Does that seem reasonable ?
Question is - do I bother ?
Only thing as regards purlin on RSJ, is its loading on one side that
could try to twist the RSJ. I'm sure I'd get away with just doing it,
but for insurance purposes, etc it may be a good idea.
Simon.

It will be money well spent for the peace of mind you get with a
proper job.
I'd say "go with the struct' eng" and make sure the whole thing
lasts the
years you want it to.

I do the same as you. I look at it for months, then decide I can do
the
work without problems, then change my mind and ask someone I know,
with a
greater experience of the actual calculations, to come in and tell
me I am
correct. But it seems to have been a good way of doing things, just
for the
peace of mind I get knowing the work is done properly.

I've had a look at the RSJ over the other side of the house (the
kitchen), and that is interestingly two parallel RSJs 3.5" by 7" with
similar flange and web sizes to the other 5" x 6" RSJ. I'm guessing
the parallel ones start with stretchers rather than headers.
It would be interesting to have seen these houses being built. Massive
gobs of lime mortar and beefy RSJs being thrown around everywhere
would be quite a sight !
Simon.


It may also be possible to do the same technique on the beam you're working
on. If the load can be spread across two similar sized RSJ's, then it might
make life a bit simpler for you.

You should see the size of the steels under our floors. We are in an old
(112 years) four storey tenement in Edinburgh, and have shops on the ground
floor, with our flat directly above. Actually, it's a five storey building
if you count the in-ground cellar spaces. The steel RSJ's are 22 inch X 9
inch and have been rolled to half an inch thick all round, with each being
11 yards in length.

I tried to calculate the weight that the four ground level ones are
carrying, above the cellar space, and gave up at the 200 ton mark. Thank
goodness there are a few spreading the loads throughout the whole building.
These old sandstone tenements were built to last. :-)

On 11 Aug, 22:32, sm_jamieson wrote:
I have just exposed the existing RSJs to which new load is to be
applied to support my roof.
The BCO said the bearings may need to be exposed but has said nothing
more. For peace of mind I
probably need a structural engineer to check things, but can anyone
give a rough feel for the loadings here ?

Old fashioned RSJ, width 125mm, height 150mm, flange thickness 10mm at
the edges, 15mm at the web,
web thickness 10mm. Span is 2800mm. Can anyone tell me what type of
loads this beam can take (assuming bearings are OK). Also, what type
of point load could it take near the middle of the span ?

Thanks,
Simon.

Right, I've thought of the best solution now, assuming the RSJ can
take the point load (struct eng ?)
Fix some timber into the web both sides of the RSJ by bolting throught
the flange M10 bolts every 600mm or so.
Then remove a single brick from the headers that are bearing directly
on the RSJ (could there be some slippage ??),
and wrap a long leg hanger up the timber, over the top and down the
back and nail in. Will hang below the RSJ like is
often done in loft conversions. Joist may need to be notched at the
top if it ends up just a little higher than the top of the RSJ.

Variation: no brick removal just fix hanger up and over the timber
infill and bolt this to the flange.

Only question - this is an RSJ with tapered flange, so I guess the
timber should be shaped at the bottom to follow the flange,
and bear in mind the bolts will be doing more than in a UB with flat
flanges. Up and over RSJ probably best, since force is more
direct onto RSJ and less the timber infill.

Which of these variations sound the best ?

Cheers,
Simon.

Simon wrote:
On 11 Aug, 22:32, sm_jamieson wrote:
I have just exposed the existing RSJs to which new load is to be
applied to support my roof.
The BCO said the bearings may need to be exposed but has said nothing
more. For peace of mind I
probably need a structural engineer to check things, but can anyone
give a rough feel for the loadings here ?

Old fashioned RSJ, width 125mm, height 150mm, flange thickness 10mm
at the edges, 15mm at the web,
web thickness 10mm. Span is 2800mm. Can anyone tell me what type of
loads this beam can take (assuming bearings are OK). Also, what type
of point load could it take near the middle of the span ?

Thanks,
Simon.

Right, I've thought of the best solution now, assuming the RSJ can
take the point load (struct eng ?)
Fix some timber into the web both sides of the RSJ by bolting throught
the flange M10 bolts every 600mm or so.
Then remove a single brick from the headers that are bearing directly
on the RSJ (could there be some slippage ??),
and wrap a long leg hanger up the timber, over the top and down the
back and nail in. Will hang below the RSJ like is
often done in loft conversions. Joist may need to be notched at the
top if it ends up just a little higher than the top of the RSJ.

Variation: no brick removal just fix hanger up and over the timber
infill and bolt this to the flange.

Only question - this is an RSJ with tapered flange, so I guess the
timber should be shaped at the bottom to follow the flange,
and bear in mind the bolts will be doing more than in a UB with flat
flanges. Up and over RSJ probably best, since force is more
direct onto RSJ and less the timber infill.

Which of these variations sound the best ?

Cheers,
Simon.


If these timber joists are hanging on only one side of the RSJ, then you
have a twisting action as the loads increase and begin pulling on that side.
Is this something you are allowing for?

Timber is at least fifteen time weaker than steel, so any infill of the web
of the RSJ will mean nothing to actual load bearing properties of the steel.
Drilling into or through the steel can change its loading character
dramatically. Holes under stress can allow cracking to take place through
the rolled grain of the RSJ in certain circumstances. 600mm spacing sounds
like one of these circumstances.

I still think spending a little time talking to, not hiring, a proper
engineer will help out on your project and let you do the works without any
faffing about. Even if you give the engineer a retainer for their
consultation, it's better than trying and failing with this type of job.

On Thu, 13 Aug 2009 23:10:02 GMT BigWallop wrote :
If these timber joists are hanging on only one side of the RSJ, then you
have a twisting action as the loads increase and begin pulling on that side.
Is this something you are allowing for?

Timber is at least fifteen time weaker than steel, so any infill of the web
of the RSJ will mean nothing to actual load bearing properties of the steel.
Drilling into or through the steel can change its loading character
dramatically. Holes under stress can allow cracking to take place through
the rolled grain of the RSJ in certain circumstances. 600mm spacing sounds
like one of these circumstances.

I agree about considering the effects of torsion, but can't see that drilling
holes in the beam will have an effect on the steel that's left. I am though a
little puzzled at the OP saying he wants to drill holes in the flange rather
than the web. Running the same calc through our ProSteel program shows that
even a 50mm hole through the web is quite OK - smaller ones for through bolts
will have a negligible effect.

I still think spending a little time talking to, not hiring, a proper
engineer will help out on your project and let you do the works without any
faffing about. Even if you give the engineer a retainer for their
consultation, it's better than trying and failing with this type of job.

No argument there. We do have SuperBeam users who offer a calcs by mail
service and others who will not do them without a site inspection. If I were
offering engineering services I would definitely be in the latter camp.

--
Tony Bryer, 'Software to build on' from Greentram
www.superbeam.co.uk www.superbeam.com www.greentram.com

On 14 Aug, 07:38, Tony Bryer wrote:
On Thu, 13 Aug 2009 23:10:02 GMT BigWallop wrote :

If these timber joists are hanging on only one side of the RSJ, then you
have a twisting action as the loads increase and begin pulling on that side.
Is this something you are allowing for?

Timber is at least fifteen time weaker than steel, so any infill of the web
of the RSJ will mean nothing to actual load bearing properties of the steel.
Drilling into or through the steel can change its loading character
dramatically. *Holes under stress can allow cracking to take place through
the rolled grain of the RSJ in certain circumstances. *600mm spacing sounds
like one of these circumstances.

I agree about considering the effects of torsion, but can't see that drilling
holes in the beam will have an effect on the steel that's left. I am though a
little puzzled at the OP saying he wants to drill holes in the flange rather
than the web. Running the same calc through our ProSteel program shows that
even a 50mm hole through the web is quite OK - smaller ones for through bolts
will have a negligible effect.

I still think spending a little time talking to, not hiring, a proper
engineer will help out on your project and let you do the works without any
faffing about. Even if you give the engineer a retainer for their
consultation, it's better than trying and failing with this type of job..


Whoops, drilling through the web of course - I "mis-wrote" !
The torsion thing I mentioned in an earlier post - yes it is a
concern.
I'm not sure how you talk to a struct eng without hiring one (unless
you have a mate)
- please let me know !
As far as 10mm holes at stated intervals - I cannot see a problem with
that. However,
I would probably drill them just either side of an exact central line.
The timber infill is not adding strength to the RSJ - it just gives a
connection method
and stabilises the hanger. If hanger is wrapped over, the top of the
RSJ takes up some
strain. Method I mentioned is standard for loft joists - at least it
has been mentioned several
times in web searches. Not always with joists hanging from both sides.
If hanger is up close, leverage is only over half the RSJ width = 2.5
inches.
Only question is added point load on RSJ, and torsion. I believe I
will have to hire a struct eng
for this - unless I meet one round the shops to talk to !
I guess the weight above the RSJ and side restraint will need to be a
factor in counteracting
the twisting forces. However, torsion would be an issue on any beam
supported off the side
of another.

I've drawn some plans for the struct eng, and he will need to do a
site visit (look at bearings).
The bearing on one end of the RSJ is quite a lot, and new support can
be offered 1/3 along the
RSJ via aircrete wall and padstone if required.

I'll let you know what the struct eng says. And if I have to pay
him ;-)


Cheers,
Simon.

On Wed, 12 Aug 2009 02:36:23 GMT, a certain chimpanzee, "BigWallop"
randomly hit the keyboard and
produced:

Also, Fire regulation now say that the steel must have a minimum of three
hour protection from direct heat along the full length of any structural
works. So allow for the BCO to add that equation once the works have begun.
Each Building Control Person seems to have their own particular way to
create an adequate heat barrier on these things, so ask them first about
this, before getting pads and other things done.

For a forty storey apartment block maybe, but not any normal house. A
two or three storey house would need 30 minutes, flats and commercial
buildings up to (IIRC) 30 metres high 60 minutes.

The pre-1985 regulations had 'deemed to satisfy' standard fire
protection details in them. Thanks to the way the regulations now
offer the designer more freedom to choose more innovative methods of
meeting the requirements, this information has been removed, and you
have to get it from the plasterboard manufacturers. They, of course
would prefer you to pick their specialist plasterboards and fixing
materials rather than use one board for all situations. So good luck
in finding out how much standard wallboard you need to give 30 minutes
fire resistance to a 7" UB.
--
Hugo Nebula
"If no-one on the internet wants a piece of this,
just how far from the pack have you strayed?"

In message , Hugo Nebula
writes
On Wed, 12 Aug 2009 02:36:23 GMT, a certain chimpanzee, "BigWallop"
randomly hit the keyboard and
produced:

Also, Fire regulation now say that the steel must have a minimum of three
hour protection from direct heat along the full length of any structural
works. So allow for the BCO to add that equation once the works have begun.
Each Building Control Person seems to have their own particular way to
create an adequate heat barrier on these things, so ask them first about
this, before getting pads and other things done.

For a forty storey apartment block maybe, but not any normal house. A
two or three storey house would need 30 minutes, flats and commercial
buildings up to (IIRC) 30 metres high 60 minutes.

The pre-1985 regulations had 'deemed to satisfy' standard fire
protection details in them. Thanks to the way the regulations now
offer the designer more freedom to choose more innovative methods of
meeting the requirements, this information has been removed, and you
have to get it from the plasterboard manufacturers. They, of course
would prefer you to pick their specialist plasterboards and fixing
materials rather than use one board for all situations. So good luck
in finding out how much standard wallboard you need to give 30 minutes
fire resistance to a 7" UB.

Hmm... I don't like the sound of *commercial* buildings needing 60 mins.
Is that for floor supporting beams only or would it include portal frame
where the roof is the main load?

Most recently constructed *change of use* barns on farms will be BS 5502
steel portal frame.

I had planned to use Oak cladding for any supporting steel in my
Victorian barn but am now concerned about meeting 60 mins fire
resistance.

regards

--
Tim Lamb

"Hugo Nebula" abuse@localhost wrote in message

On Wed, 12 Aug 2009 02:36:23 GMT, a certain chimpanzee, "BigWallop"
randomly hit the keyboard and
produced:

Also, Fire regulation now say that the steel must have a minimum of
three hour protection from direct heat along the full length of any
structural works. So allow for the BCO to add that equation once the
works have begun. Each Building Control Person seems to have their own
particular way to create an adequate heat barrier on these things, so
ask them first about this, before getting pads and other things done.

For a forty storey apartment block maybe, but not any normal house. A
two or three storey house would need 30 minutes, flats and commercial
buildings up to (IIRC) 30 metres high 60 minutes.

The pre-1985 regulations had 'deemed to satisfy' standard fire
protection details in them. Thanks to the way the regulations now
offer the designer more freedom to choose more innovative methods of
meeting the requirements, this information has been removed, and you
have to get it from the plasterboard manufacturers. They, of course
would prefer you to pick their specialist plasterboards and fixing
materials rather than use one board for all situations. So good luck
in finding out how much standard wallboard you need to give 30 minutes
fire resistance to a 7" UB.


This might help
http://www.mace.manchester.ac.uk/pro...faultSteel.htm

It's a lot of reading, but worth the effort.

On 14 Aug, 08:39, Simon wrote:
On 14 Aug, 07:38, Tony Bryer wrote:



On Thu, 13 Aug 2009 23:10:02 GMT BigWallop wrote :

If these timber joists are hanging on only one side of the RSJ, then you
have a twisting action as the loads increase and begin pulling on that side.
Is this something you are allowing for?

Timber is at least fifteen time weaker than steel, so any infill of the web
of the RSJ will mean nothing to actual load bearing properties of the steel.
Drilling into or through the steel can change its loading character
dramatically. *Holes under stress can allow cracking to take place through
the rolled grain of the RSJ in certain circumstances. *600mm spacing sounds
like one of these circumstances.

I agree about considering the effects of torsion, but can't see that drilling
holes in the beam will have an effect on the steel that's left. I am though a
little puzzled at the OP saying he wants to drill holes in the flange rather
than the web. Running the same calc through our ProSteel program shows that
even a 50mm hole through the web is quite OK - smaller ones for through bolts
will have a negligible effect.

I still think spending a little time talking to, not hiring, a proper
engineer will help out on your project and let you do the works without any
faffing about. *Even if you give the engineer a retainer for their
consultation, it's better than trying and failing with this type of job.

Whoops, drilling through the web of course - I "mis-wrote" !
The torsion thing I mentioned in an earlier post - yes it is a
concern.
I'm not sure how you talk to astructengwithout hiring one (unless
you have a mate)
- please let me know !
As far as 10mm holes at stated intervals - I cannot see a problem with
that. However,
I would probably drill them just either side of an exact central line.
The timber infill is not adding strength to the RSJ - it just gives a
connection method
and stabilises the hanger. If hanger is wrapped over, the top of the
RSJ takes up some
strain. Method I mentioned is standard for loft joists - at least it
has been mentioned several
times in web searches. Not always with joists hanging from both sides.
If hanger is up close, leverage is only over half the RSJ width = 2.5
inches.
Only question is added point load on RSJ, and torsion. I believe I
will have to hire astructeng
for this - unless I meet one round the shops to talk to !
I guess the weight above the RSJ and side restraint will need to be a
factor in counteracting
the twisting forces. However, torsion would be an issue on any beam
supported off the side
of another.

I've drawn some plans for thestructeng, and he will need to do a
site visit (look at bearings).
The bearing on one end of the RSJ is quite a lot, and new support can
be offered 1/3 along the
RSJ via aircrete wall and padstone if required.

I'll let you know what thestructengsays. And if I have to pay
him ;-)

Cheers,
Simon.

Well, I've had a local struct eng round. I'd told him the rough
details on the phone, and he was umming and ahhing about the double
RSJ I mentioned before. When he found out the floor load was on the
side walls and not the RSJs had said it "oh, its fine then".

He OK'd my plans for hanging one purlin off the RSJ with timber bolted
to the web and jiffy hangers, and said the existing weight on the RSJ
from the wall above was sufficient to overcome torsional forces.
He made a lot of fuss telling me how to fit masonry joist hangers for
some reason, but said to dry pack above the joist hanger flange and
leave it a week before the main roof tile load goes on.

He had done some calcs after I phoned him, but only charged me for
verbal advice (100 quid + VAT), and will write me a letter detailing
his general advice but without calcs. If the BCO was calcs at any
point, he'll get the info from his file and do the calcs for me (for
another 100 quid !)

Now I need to work out how to drill 10mm holes in the web of the RSJ.
10mm thick. Best drill bit, cutting paste etc ?

Simon.

In message
,
Simon writes
Now I need to work out how to drill 10mm holes in the web of the RSJ.
10mm thick. Best drill bit, cutting paste etc ?

Start small and work up to 10mm.

regards

--
Tim Lamb

We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember Simon
saying something like:

Now I need to work out how to drill 10mm holes in the web of the RSJ.
10mm thick. Best drill bit, cutting paste etc ?

Hire a magnetic clamp drill, and the job's much, much easier.