load capacity of 6x6pt 6' span

[Soundguy]

i left my %$# black book on my desk and I'm out driving between jobs. ( only posting at stoplamps! )

offhand anyone know the load capacity of a 6x6 pt, 6' span between supports?

thanks

soundguy

 

[rtimgray]

I have an old table from "Wood Structural Design Data" that says the safe load for a dressed (S4) 6x6 beam at 6' is 3,697 lbs (it's 2,772 if you go to 8'). I just have an old waterstained photocopy, but I think it came from an old Pole Building book that I checked out from the library years ago.

Hope this helps.

 

[Soundguy]

thanks, That's even better than I was looking at. I used a quick span calc for a 1960# load, so i am good to go. double checked it on some other tables and looks good.

thanks

soundguy

 

[LD1]

thanks, That's even better than I was looking at. I used a quick span calc for a 1960# load, so i am good to go. double checked it on some other tables and looks good.

thanks

soundguy

So......what are you building and how much load do you for see????

And is this a mid-point single load.....or an evenly distributed load?

 

[Soundguy]

I could use up to 2000# of capacity if i had it available.. if I calculate less I'll plan for less.. while some of the load could be single middle I actually plan for it to be spread out over a 4' section. i need to build a low 'gantry' to swing a n implement on for repair or painting. have been using loaders.. but i don't get the side clearance I need, and overspray is always an issue, plus I don't work under unsupported hyds, so i always have to block the load with 6x6 timbers anyway.. so since I have them on handi was going to rig up a cradle.

soundguy

 

[LD1]

I have an old table from "Wood Structural Design Data" that says the safe load for a dressed (S4) 6x6 beam at 6' is 3,697 lbs (it's 2,772 if you go to 8'). I just have an old waterstained photocopy, but I think it came from an old Pole Building book that I checked out from the library years ago.

Hope this helps.

That is a little higher than what I came up with. That may be for hardwood beams???

thanks, That's even better than I was looking at. I used a quick span calc for a 1960# load, so i am good to go. double checked it on some other tables and looks good.

thanks

soundguy

Thats a little closer. Ofcourse the more distributed the load is, the higher the capacity. But I based my # on the following:

6' span
6x6 (5.5x5.5 nominal) SYP lumber. IF it is something other than SYP, the results will be different.
Assuming a SINGLE point load dead center,

Your MAX would @ L/360 deflection (which means the beam will deflect 0.2" at max) is.......2353#:thumbsup:

 

[Soundguy]

yep, i looked at lp 240/360 and hit it conservatively, so I'm fine.

thanks guys.

and in fact.. i think my 1961# # was for a 7' span when I punched it in.

either way I'm good, thanks!

 

[LD1]

6' span with L/360 deflection = 2353# max
6' span with L/240 deflection = 3530# max
7' span with L/360 deflection = 1728# max
7' span with L/240 deflection = 2593# max

So yea, I think you will be fine whatever you do. Even if you wanted a 7' span. Because honestly, you could even use L/180 deflection if you wanted for what you are doing.

The L/360 is mostly for floor joists and such that would look like crap if they sagged. So minimal deflection is a must in a case like that. In reality though, wood will deflect ALOT before it breaks.

Think about it this way...alot of pole barns are built with 2x4 purlins laid flat and spanning 4'. Using L/360, technically they should only be able to support 68 lbs.:confused2: And I know for a fact that one of them can support my WHOLE body weight at ~3x's that. :confused2:

 

[Soundguy]

yep, on an acceptable deflection ( not really relevant even) on a 7' span, 2000# will be quite safe... fiber stress of most wood / beams is about 1100 psi..