Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

Re: Structural steel--isolated joints

[Subject Prev][Subject Next][Thread Prev][Thread Next]
"I'd say that when that crane shakes the displacement is just about what it
would be if the pipe weren't there."

I'd agree, however the attachment is only a foot or  so above the columns
attachment to the primary crane support bent (two 10"x .25 wall pipes laced
together) so there is some resistance there and the column is relatively
stiff. It could be reasoned that the attachment is the main culprit to the
damage therefore don't reattach the new column right? Well I'd rather not go
that route... but if I can reattach it loosely, let the rail beam do it's
thing but restrain the beam if it walks too far. I witnessed the rail beam's
top flange moving at the rail beam splice as the crane passed, and it was
loaded with maybe 10 tons






----- Original Message ----- 
From: "Christopher Wright" <chrisw(--nospam--at)skypoint.com>
To: "SEAOC Newsletter" <seaint(--nospam--at)seaint.org>
Sent: Monday, August 09, 2004 11:25 PM
Subject: Re: Structural steel--isolated joints


> >I knew you'd have good information... and you didn't even say anything to
> >offend me,
> Call it a senior moment. ;->
>
> >Are you saying in this case lateral softness is a bad thing?
> Low frequency systems tend to deflect more and I think you want to avoid
> this.
>
> It's not entirely apparent what stiffens what. Hard to imagine that 64000
> lb machine including dynamic amplification wouldn't take a 6 in pipe
> anywhere it felt like. I'm guessing, not having seen the site, but I'd
> say that when that crane shakes the displacement is just about what it
> would be if the pipe weren't there. The loading on the pipe is probably
> limited by the crane displacement, which is the only reason the column
> didn't fracture years ago.
>
> If you're using the HSS section to stabilize the crane girder, it has to
> be able to carry the corresponding loads. If you attach the two members
> elastically to limit the loading you defeat the stabilization. You might
> want to get some notion about the loading and displacement that the crane
> imposes in the HSS section to see if it's really doing anything. Part of
> the reason the crane shakes might be that the column doesn't actually
> stiffen it, rather it just rides along. Check the relative stiffness
> while you're at it, to see what supports what. I think if this were my
> problem I'd take a good look at the rest of the structure, to see if the
> vibration might be affecting the other supports. The rail misalignment
> really beats the hell out of the machine. It'd be a good idea to remedy
> that while you're about it.
>
> Christopher Wright P.E.    |"They couldn't hit an elephant at
> chrisw(--nospam--at)skypoint.com        | this distance"   (last words of Gen.
> ___________________________| John Sedgwick, Spotsylvania 1864)
> http://www.skypoint.com/~chrisw
>
>
>
> ******* ****** ******* ******** ******* ******* ******* ***
> *   Read list FAQ at: http://www.seaint.org/list_FAQ.asp
> *
> *   This email was sent to you via Structural Engineers
> *   Association of Southern California (SEAOSC) server. To
> *   subscribe (no fee) or UnSubscribe, please go to:
> *
> *   http://www.seaint.org/sealist1.asp
> *
> *   Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you
> *   send to the list is public domain and may be re-posted
> *   without your permission. Make sure you visit our web
> *   site at: http://www.seaint.org
> ******* ****** ****** ****** ******* ****** ****** ********
>



******* ****** ******* ******** ******* ******* ******* ***
*   Read list FAQ at: http://www.seaint.org/list_FAQ.asp
* 
*   This email was sent to you via Structural Engineers 
*   Association of Southern California (SEAOSC) server. To 
*   subscribe (no fee) or UnSubscribe, please go to:
*
*   http://www.seaint.org/sealist1.asp
*
*   Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you 
*   send to the list is public domain and may be re-posted 
*   without your permission. Make sure you visit our web 
*   site at: http://www.seaint.org 
******* ****** ****** ****** ******* ****** ****** ********