The Forestry Forum is sponsored in part by:

iDRY Vacuum Kilns


Forestry Forum
Sponsored by:


TimberKing Sawmills



Toll Free 1-800-582-0470

LogRite Tools



Norwood Industries Inc.




Your source for Portable Sawmills, Edgers, Resaws, Sharpeners, Setters, Bandsaw Blades and Sawmill Parts

EZ Boardwalk Sawmills. More Saw For Less Money!

STIHLDealers.com sponsored by Northeast STIHL


Woodland Sawmills

Peterson Swingmills

 KASCO SharpTech WoodMaxx Blades

Turbosawmill

Sawmill Exchange

Michigan Firewood, your BRUTE FORCE Authorized Dealer

FARMA


Baker Products

ECHO-Bearcat

iDRY Wood Lumber Vacuum Drying for everyon

Nyle Kiln Dry Systems






Author Topic: Free span with hammer beam truss Qs  (Read 3452 times)

0 Members and 1 Guest are viewing this topic.

Offline Rooster

  • Senior Member
  • ****
  • Posts: 688
  • Location: Lake Mills, by way of Fort Atkinson, WI
  • Gender: Male
  • Tools are extensions of ourselves... share a tool.
    • Share Post
    • Photobucket image storage account
Free span with hammer beam truss Qs
« on: August 16, 2009, 03:41:48 PM »
I have a potential client who is looking into building a 70ft wide free-span timberframe shop with about an 8/12  +/- pitch saltbox roof.   ???  :o (That's  what I thought!!)

What is the widest building width that a hammer beam truss can appropriately span?


Or has anyone built a timberfame girder truss to span long widths?

Looking for options and direction, ..."no need to re-invent the wheel"

Rooster
"We talk about creating millions of "shovel ready" jobs, for a society that doesn't really encourage anybody to pick up a shovel." 
Mike Rowe

"Old barns are a reminder of when I was young,
       and new barns are a reminder that I am not so young."
                          Rooster

Offline Raphael

  • Senior Member x2
  • *****
  • Posts: 1116
  • Age: 57
  • Location: Warren, CT
  • Gender: Male
  • Willing and able to do a boring job.
    • Share Post
Re: Free span with hammer beam truss Qs
« Reply #1 on: August 16, 2009, 06:50:07 PM »
This is definitely one for the engineers.  Wrangling the assymetrical forces of a saltbox roof under a single truss will be quite a challenge, have you got a sketch?

I've seen hammer beams spanning ~60ft and suspect some cathedrals go even wider, but these are buttressed structures.  A scissors truss might be another option.

As for the TF girder, I haven't done it but it's essentially the same problem as a bridge.
The Guelph bridge (a 1992 guild project) is 120' clear span.
... he was middle aged,
and the truth hit him like a man with no parachute.
 --Godley & Creme

Stihl 066, MS 362 C-M & 24+ feet of Logosol M7 mill

Offline moonhill

  • Senior Member x2
  • *****
  • Posts: 1379
  • Location: Down East, Maine
    • Share Post
Re: Free span with hammer beam truss Qs
« Reply #2 on: August 16, 2009, 08:19:43 PM »
I would say the possible client does not understand the hammer beam "truss".  Is this their idea?  Did it come from a glossy magazine?  Buttress indeed. 

If the building is 70' wide how long is it?

I have an engineer now looking at a 36' queen rod truss for my next possible up coming job.

Tim


This is a test, please stand by...

Offline Rooster

  • Senior Member
  • ****
  • Posts: 688
  • Location: Lake Mills, by way of Fort Atkinson, WI
  • Gender: Male
  • Tools are extensions of ourselves... share a tool.
    • Share Post
    • Photobucket image storage account
Re: Free span with hammer beam truss Qs
« Reply #3 on: August 17, 2009, 02:32:31 AM »
Thanks guys,

I haven't received a sketch yet, but I do know that the building is divided up into two halves...one end is a 42ft wide x 56ft gambrel roof style, two story draft horse barn, which also has 14ft x 56ft lean-to additions attached to each side.

42 +14+14=70ft

The other end of the building is the 70ft x100ft free span, saltbox style roof, timberframe farm and mechanics/ maintenence shop. 

70ft x 156ft total footprint.

He likes the look of old timber and is asking that it be made out of used barn material.  I have built a 51ft Multiple Kingpost truss covered bridge, so I feel more comfotable with that sort of system.  I also looked at some of the Guild's truss literature and found a couple of Queen/King truss combinations that would work for a shorter span.  We are still in the early stages of planning, and I have a couple of alternatives/compromises to propose if needed.

Tim,

30-36ft Queen trusses with hanging support rods are very common in Wisconsin Dairy barns built between c.1890-1920.  Let me know if you want to pick my brain on that one.

Rooster
"We talk about creating millions of "shovel ready" jobs, for a society that doesn't really encourage anybody to pick up a shovel." 
Mike Rowe

"Old barns are a reminder of when I was young,
       and new barns are a reminder that I am not so young."
                          Rooster

Offline Mad Professor

  • Senior Member
  • ****
  • Posts: 497
  • Age: 2016
  • Location: Northeast
    • Share Post
Re: Free span with hammer beam truss Qs
« Reply #4 on: August 17, 2009, 05:52:27 AM »
I been in some churches with large span hammer truss design.  The walls are mortared stone with a substantial buttress, also of stone, to support the outward thrust of each truss.

I think you will also have to consider a heavy snow load..........


Share via delicious Share via digg Share via facebook Share via linkedin Share via pinterest Share via reddit Share via stumble Share via tumblr Share via twitter

question
Minimum Pitch for a Hammer Beam Truss?

Started by Woodbender on Timber Framing/Log construction

16 Replies
21086 Views
Last post February 24, 2007, 01:12:26 PM
by Thomas-in-Kentucky
xx
Truss Design for 24' Free Span w/Attic Storage

Started by stilloggin on Timber Framing/Log construction

4 Replies
3972 Views
Last post November 10, 2006, 06:35:39 AM
by Max sawdust
xx
25ft Span Post Free: Milling My Own Beam Need Help!

Started by jemmy on Timber Framing/Log construction

6 Replies
849 Views
Last post October 06, 2017, 07:22:09 PM
by Mad Professor
xx
Clear Span Roof Truss Calculator

Started by Sedgehammer on Timber Framing/Log construction

151 Replies
7459 Views
Last post November 13, 2019, 10:35:03 AM
by Don P
 


Powered by EzPortal