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Re: stainless steel cable

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Chuck,
 
Good point, did not think of this one. 
 
If the end (terminal) post is made out of wood, it may be really affected.  The pretension may create shear and flexural stress (say, 12 to 16 KSI) that are high even for Ipe.  When the post moves/yields, the tension is gone, and the cables are loose.
 
But may be, the cables are anchored into the abutments?  With the steel plates Yi mentioned, this may somewhat mitigate the situation.  
 
Steve Gordin, SE 
----- Original Message -----
Sent: Tuesday, May 24, 2005 11:14 AM
Subject: Re: stainless steel cable

I suggest you go back in a few months & check it again.  Creep in wood is a killer for these things.  If some little kid gets hurt, this is really going to seem like a bad idea.
Chuck Utzman, P.E.

Yi Yang wrote:
We just did a project, included a exact same scenario as you described.  It was a pedestrian wood bridge on a private property, with 4x4 IPE post.  The cables were spaced at 3" apart, so to satisfy the requirement, the max deflection for the cable needs to be 1" or less with 50lbs point load at mid span.
I calculated the tension on the cable to be about 350 lbs for it have a 1" or less deflection when a 50lbs force is at the mid span (ignore the cable weight).  When the cable was installed, the post had a little splitting problem, so they put the steel plate on the back side.  The contractor put a bucket of sand, 50lbs, at the middle, and tighten the cable, while measuring it with a level and tape, until the deflection is about 1".  The cable supplier had a spring loaded gage to measure the tension, and it came out to be about 360 lbs.  The county building inspector was happy with that.
 
 
 
Y i   Y a n g,   S. E.            
STRUCTURAL DIVISION
SUMMIT ENGINEERING INC.
707.527.0775.x15
Santa Rosa, California
 


From: S. Gordin [mailto:mailbox(--nospam--at)sgeconsulting.com]
Sent: Monday, May 23, 2005 9:36 PM
To: seaint(--nospam--at)seaint.org
Subject: Re: stainless steel cable

Thank you, Harold.
 
It is a guard rail for a pedestrian bridge.  The manufacturer sang me a good old "We've done it for many years, worked just fine."     
 
To make a long story short, after I posted my question, I searched online, and found the spec for such railing at Johnson Architectural Site.  That spec generally conformed what I found earlier analytically - the maximum spacing of the posts and cables, and pretension required not to allow a 4" sphere to pass through.  The "good old" solution came out to be not that adequate.
 
But seriously, who would want to actually pull those cables apart and stick his head in?  Can happen though...
 
V. Steve Gordin, PhD
Registered Structural Engineer
Irvine CA
  
    
----- Original Message -----
Sent: Monday, May 23, 2005 7:51 PM
Subject: RE: stainless steel cable

Is this a "guard rail", "hand rail", or "passenger vehicle guard rail". 
There is an article that was published some years ago, but is still valid. 
I am out of the office right now, but I will look into it when I return.  A
lot of it has to do with how you plan to anchor it.  They can be anchored
with wedges, preform anchors, or loops on thimbles and using eye bolts.

Regards,
Harold Sprague




>From: "S. Gordin" <mailbox(--nospam--at)sgeconsulting.com>
>Reply-To: <seaint(--nospam--at)seaint.org>
>To: "Seaint(--nospam--at)Seaint. Org" <seaint(--nospam--at)seaint.org>
>Subject: stainless steel cable
>Date: Mon, 23 May 2005 11:33:35 -0700
>
>Good Morning,
>
>Can anybody recommend me some down-to-earth manual for the design of
>stainless steel cables? Nothing fancy, just railing.
>
>TIA,
>
>Steve Gordin, SE
>Irvine CA

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