I'm trying to calculate some stresses and stuff for a new platform/
stairway design, and I have a question about a stairway. I've got
the formulas for beams and stuff, but I'm wondering - I have a
diagram he

http://mysite.verizon.net/richgrise/...RS_Layout1.pdf

The stairway is supposed to support 1,000 lbs per step. Now, in
this diagram, the black numbers are dims in inches, and the red
numbers are supposed to correspond to pounds - can I treat that
as a vector and "resolve" it to 806# along the length of the stringer,
and 591# perpendicular to the stringer, such that I only need to do
the stress for the 591?

Thanks,
Rich

Rich Grise wrote:

can I treat that
as a vector and "resolve" it to 806# along the length of the stringer,
and 591# perpendicular to the stringer, such that I only need to do
the stress for the 591?

For bending (which will be the most interesting part): Yes.

But a sidenote: 51° for a stair is *absolutely* not acceptable. You can walk
upstairs, but not down.


Nick
--
The lowcost-DRO:
http://www.yadro.de

On Wed, 06 Feb 2008 19:56:05 +0000, Howard Eisenhauer wrote:
On Wed, 06 Feb 2008 20:48:29 +0100, Nick Mueller
Rich Grise wrote:

can I treat that
as a vector and "resolve" it to 806# along the length of the stringer,
and 591# perpendicular to the stringer, such that I only need to do
the stress for the 591?

For bending (which will be the most interesting part): Yes.

But a sidenote: 51° for a stair is *absolutely* not acceptable. You can walk
upstairs, but not down.

My first thought was-

"That ain't a stairway, Its a Ladder"

But I've seen as bad as that in many buildings getting up to the roof
top or equipment penthouse. It certainly wouldn't meet code for any
public area or residence though.

I guess I'll have to use ladder rules, then. :-)

What it's for is access to a radiotelescope tower, so there's no public
access. (i.e., workers can theoretically be trained. ;-) )

Thanks!
Rich

Howard Eisenhauer wrote:

But I've seen as bad as that in many buildings getting up to the roof
top or equipment penthouse.

Unsuited for frequent access. Once a year is OK.

It certainly wouldn't meet code for any
public area or residence though.

You'll only come down backwards. Or the stairs are samba-style (if you are
using that expression. If not: http://de.wikipedia.org/wiki/Sambatreppe).
But still they are a pain and quite dangerous.


Nick
--
The lowcost-DRO:
http://www.yadro.de

Nick Mueller wrote:

Howard Eisenhauer wrote:

But I've seen as bad as that in many buildings getting up to the roof
top or equipment penthouse.

Unsuited for frequent access. Once a year is OK.

It certainly wouldn't meet code for any
public area or residence though.

You'll only come down backwards. Or the stairs are samba-style (if you are
using that expression. If not: http://de.wikipedia.org/wiki/Sambatreppe).
But still they are a pain and quite dangerous.

Nick
--
The lowcost-DRO:
http://www.yadro.de

Seems like a standard ship ladder, can't be that dangerous, just need to
have a clue. I believe they are available as pre-fab off the shelf items
from some of the regular ladder manufacturers.

Nick Mueller wrote:

Howard Eisenhauer wrote:

But I've seen as bad as that in many buildings getting up to the roof
top or equipment penthouse.

Unsuited for frequent access. Once a year is OK.

It certainly wouldn't meet code for any
public area or residence though.

You'll only come down backwards. Or the stairs are samba-style (if you are
using that expression. If not: http://de.wikipedia.org/wiki/Sambatreppe).
But still they are a pain and quite dangerous.

Nick
--
The lowcost-DRO:
http://www.yadro.de

That samba stair is certainly interesting.

BTW, the ships ladder stairs are quite useable forwards without killing
yourself. I've done it personally multiple times while shooting video at
the same time.

"Nick Mueller" wrote in message
...
Howard Eisenhauer wrote:

But I've seen as bad as that in many buildings getting up to the roof
top or equipment penthouse.

Unsuited for frequent access. Once a year is OK.



Working in commercial HVAC I deal with these types of stairs everyday. I do
agree they do not meet code any where, at least for public access, but the
once a year use comment is pretty extreme! if the stairs are used by a
limited number of people, a few times a day they should be fine. Again,
local code may dictate otherwise.
Greg

You'll only come down backwards. Or the stairs are samba-style (if you are
using that expression. If not: http://de.wikipedia.org/wiki/Sambatreppe).
But still they are a pain and quite dangerous.


Otherwise known as alternating tread stairs. I ordered one for a storage
mezzanine in our building. Lapeyre is the main supplier of them in the US, here
is a link to some photos, try the fourth one for a comparison to regular
stairs:

http://www.lapeyrestair.com/products...?albm=atsSteel

They have a funny feel to them as you use them. The effective rise is very
small, so you go up slowly compared to regular stairs.

--
Dennis