|
Heavy Duty Scarf Joint Design
#20560
07/04/09 07:55 AM
|
Joined: Mar 2002
Posts: 961
Ken Hume
OP
Member
|
OP
Member
Joined: Mar 2002
Posts: 961 |
Hi,
Can anyone point me towards a downloadable book or paper that illustrates various options and considerations for the design of a very heavy duty scarf joint. I would imagine that this might well be included within the pages of a bridge building manual or the like. I am looking for inspiration to help establish a good timber / bolted / banded design that is capable of medium to longer term adjustment.
Regards
Ken Hume
Looking back to see the way ahead !
|
|
|
Re: Heavy Duty Scarf Joint Design
[Re: Ken Hume]
#20562
07/04/09 11:20 AM
|
Joined: Dec 2007
Posts: 1,882
TIMBEAL
Member
|
Member
Joined: Dec 2007
Posts: 1,882 |
Here is one Ken. http://www.tfhrc.gov/structur/pubs/04098/14.htmWill T. should have some stuff. It will be interesting to see what you come up with for this scarf. How long is the timber you are making, 68' was it? Tim
|
|
|
Re: Heavy Duty Scarf Joint Design
[Re: TIMBEAL]
#20563
07/04/09 12:34 PM
|
Joined: Mar 2002
Posts: 961
Ken Hume
OP
Member
|
OP
Member
Joined: Mar 2002
Posts: 961 |
Hi Tim,
This is a good document and just the very thing needed to kick start the brain into action to think about the issues that need to be addressed. The composite will be 84'.
Regards
Ken Hume
Looking back to see the way ahead !
|
|
|
Re: Heavy Duty Scarf Joint Design
[Re: Ken Hume]
#20566
07/04/09 06:57 PM
|
Joined: Jan 2008
Posts: 918
bmike
Member
|
Member
Joined: Jan 2008
Posts: 918 |
that is capable of medium to longer term adjustment.
what does that mean? in what context will you be 'adjusting' it?
|
|
|
Re: Heavy Duty Scarf Joint Design
[Re: bmike]
#20567
07/05/09 03:04 AM
|
Joined: Nov 2006
Posts: 850
mo
Member
|
Member
Joined: Nov 2006
Posts: 850 |
Hey All, here is a good one. Strongest one I know of W/O bolts. All wood, opposing keys (in the 5" slot) to knock around down the road. Precision is beneficial on this one, otherwise you might get some splitting at the abutments (sp?). my apologies for the sloppy ink, from awhile ago. Great Scarf Joint. A little labor intensive, but in the grand scheme of things.... Happy 4th!
|
|
|
Re: Heavy Duty Scarf Joint Design
[Re: mo]
#20569
07/05/09 07:25 AM
|
Joined: Mar 2002
Posts: 961
Ken Hume
OP
Member
|
OP
Member
Joined: Mar 2002
Posts: 961 |
Hi M & M.
The wood is bound to dry in service and so it would be important to be able to tighten up any metal bolts or hoops employed so that the joint can be kept tight in service.
Regards
Ken Hume
Last edited by Ken Hume; 07/05/09 07:26 AM.
Looking back to see the way ahead !
|
|
|
Re: Heavy Duty Scarf Joint Design
[Re: Ken Hume]
#20570
07/06/09 03:36 AM
|
Joined: Nov 2006
Posts: 850
mo
Member
|
Member
Joined: Nov 2006
Posts: 850 |
Ken,
I don't see the point in your new thread. You have asked a question about a reasonable issue, but have given no circumstances.
I am lost in this thread.
Last edited by mo; 07/06/09 03:39 AM.
|
|
|
Re: Heavy Duty Scarf Joint Design
[Re: Will Truax]
#20573
07/06/09 03:52 PM
|
Joined: Mar 2002
Posts: 961
Ken Hume
OP
Member
|
OP
Member
Joined: Mar 2002
Posts: 961 |
Hi Will,
Thanks for those links - both of which seem to require registration and paying a fee. I agree that English Historic Carpentry is also my usual start point for selecting an all timber scarf joint as found mainly in buildings. Unfortunately this scarf joint is unsupported and will have to generate the same load, moment and shear carrying capacity as a continuous timber, hence the already recognised need for metal reinforcement. The marriage of differing materials is not uncommon in bridge, mill and ship building (rope / timber mast joints) and, thinking aloud, I seem to recall that the TFG Lexington Bellifortis trebuchet mast was banded to help hold it together. I shall need to retrieve TF No 44 to see what clues and / or design considerations are detailed within.
The manual reference provided by Tim is excellent and its worthy of note that the engineering for this document was done by Dr. B Brungraber.
Mo,
Thank you for your contributions. I did say at the outset that this was to be a heavy duty joint and would need a bolted / banded design.
Please don't punish yourself (or me) - all will be revealed in due course when I am a little more confident (or not !) about being able to produce a workable design solution. Regards
Ken Hume
Looking back to see the way ahead !
|
|
|
Re: Heavy Duty Scarf Joint Design
[Re: Ken Hume]
#20574
07/06/09 04:09 PM
|
Joined: Mar 2002
Posts: 961
Ken Hume
OP
Member
|
OP
Member
Joined: Mar 2002
Posts: 961 |
Hi,
I have now retrieved TF No 44 and Colonel Neel says "some main beams appear to be made up of several pieces scarfed and laminated, held together with Dutch pins and bound with rope coils, or with iron bands". What are Dutch pins ?
Regards
Ken Hume
Last edited by Ken Hume; 07/06/09 04:11 PM.
Looking back to see the way ahead !
|
|
|
|
|
|
|