STRUCTURAL QUESTION

anyone have a chart or know what is the amount of weight that can be applied
to 1 1/4" square tube with 1/8" wall at a span of 5 foot to achieve minimum
deflection ... . I have been using it for handrail for per a customer's
specs, & did some for another customer that is questioning the size of it.
all OSHA says is strong enough to withstand 200 lbs with minimum deflection


TIA
Rob

 

A steel industry handbook (assuming it's steel) will give you the specs you
will need to perform a
calculation for deflection. What's "minimum deflection"? Is that 200# a
point or distributed?
In these parts the building code specifies the load conditions to be met
by a handrail and a guard. Have you checked your local code?

 

yes, steel A36 , 200# on any 2" point...
usually the customer is responsible for permits & "design" we merely
fabricate.. of course it takes more than a scratchpad to actually get it
built(my job), but the concept & liability is generally left to the
customer.

 

If the client is designing it and takes responsibility, why are
you worrying about it?

 

I said usually.. this is a different client, I am not worried about it ~
other than it not being up to osha's standard, which only states that it
must withstand 200# w/minimal deflection., I jumped my fat ass up & down on
it. )

 

Are you working for/with engineers?
I wouldn't stick out my neck as far as
liability goes for what probably wasn't enough
money. BTW, what's "minimal"? 1/480? 1/360?
It's a handrail, right?

 

Are you working for/with engineers?

yeah, engineers at various companies, usually process or chemical engineers,
not much help in the line of structural questions. according to OSHA.
minimal deflection is only described in another section which states that
under the 200 lb stress test, the rail cannot bend to a point less than 39"
high.
(which started with a total height of 42" Tall) it's really not clear.

 

3" in a 60" span is totally MASSIVE deflection,
and probably not one from which the member
could recover. You can't have that right.

If your engineers are stamping the work then it's not
your problem unless it's one of those places where it ALWAYS your
problem when stuff goes wrong, even though you're not in charge...

 

in theory my company does NOT do design, of course the people giving us the
jobs have no idea how or what it takes to build their ideas, so we "lay it
out" (make fabrication prints) & and have them approve the drawing before
construction. there's some small print on our blueprints that pretty much
says all that, I really don't know if it amounts to much legally.
I always thought it was an ISO thing. the 3" defelction doesn't freak me
out, i mean , i think we could actually use wooden 2x4's & keep OSHA
satisfied.. i dunno, it's not my call apparently.
Rob

 

You're probably right, a 2x4 should do the trick for a handrail load
depending on the span of course. However,
I think you've probably misread the code. It probably allows for
deviation for a specified height, or declares a minimum height.
The three inches may be the difference between what you have
drawn and what is required, but I don't think that 3" in 60" is an
acceptable
deflection in for ANYTHING accept a structure meant to be used once
and discarded after deformation.

 

I disagree, I need a chart that shows acceptable materials at specific
spans. I have seen them, I just can't seem to find one right now,

 

You really didn't think an engineer would tell you to go by published
material, did you?