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RE: STRUCTURAL STEEL: Large Pipe Column?

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Bill - We do have large cantilevers, and we have looked at fatigue.  We are currently handling this by using gusset plates at the base of our cantilever.

Amy Irwin Ellis, EIT
Carter & Burgess, Inc.
777 Main Street
Fort Worth, Texas 76101-2053
Tel: 817-735-7192
Fax: 817-735-6148
email: EllisAL(--nospam--at)c-b.com


>>> bill(--nospam--at)polhemus.cc 02/28/02 01:54PM >>>
Yes, Amy. This is from the AASHTO "Standard Specifications for Structural
Supports for Highway Signs, Luminaires and Traffic Signals," Fourth Edition
(2001), which IIRC you have.

Please note that in this case I'm designing a CANTILEVER STRUCTURE (i.e.
single column). There is apparently some research ongoing to determine
fatigue design parameters for "bridge type" structures, but the current
edition of the AASHTO Specification doesn't address such structures.

In the Commentary in Section 11: Fatigue Design, there is the following
passage:

"Square cross-sections have been much more prone to fatigue problems than
round cross-sections."

In the past, the Houston District of TxDOT has designed cantilever sign
supports using square tubes. I do not know what their record of performance
has been but I do note that they no longer allow such designs.

HTH.




William L. Polhemus, Jr. P.E.
Polhemus Engineering Company
Katy, TX, USA
Phone (281) 492-2251
FAX (281) 492-8203
email bill(--nospam--at)polhemus.cc

-----Original Message-----
From: Amy Ellis [mailto:EllisAL(--nospam--at)c-b.com]
Sent: Thursday, February 28, 2002 1:12 PM
To: seaint(--nospam--at)seaint.org
Cc: Greg Creamer; Darrell Thompson; vkimm(--nospam--at)hdrinc.com
Subject: RE: STRUCTURAL STEEL: Large Pipe Column?

Bill,

I am working on a project for the new Terminal out at DFW Airport.  DFW
specifies HSS 16x16 tubes for all overhead signs.  I was wondering about
your statement regarding not using rectangular tubes in the state of Texas
due to fatigue.  Could you elaborate on this point or let me know where to
look to find out more information.



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Bill - We do have large cantilevers, and we have looked at fatigue.  We are currently handling this by using gusset plates at the base of our cantilever.
 
Amy Irwin Ellis, EIT
Carter & Burgess, Inc.
777 Main Street
Fort Worth, Texas 76101-2053
Tel: 817-735-7192
Fax: 817-735-6148
email: EllisAL(--nospam--at)c-b.com


>>> bill(--nospam--at)polhemus.cc 02/28/02 01:54PM >>>
Yes, Amy. This is from the AASHTO "Standard Specifications for Structural
Supports for Highway Signs, Luminaires and Traffic Signals," Fourth Edition
(2001), which IIRC you have.

Please note that in this case I'm designing a CANTILEVER STRUCTURE (i.e.
single column). There is apparently some research ongoing to determine
fatigue design parameters for "bridge type" structures, but the current
edition of the AASHTO Specification doesn't address such structures.

In the Commentary in Section 11: Fatigue Design, there is the following
passage:

"Square cross-sections have been much more prone to fatigue problems than
round cross-sections."

In the past, the Houston District of TxDOT has designed cantilever sign
supports using square tubes. I do not know what their record of performance
has been but I do note that they no longer allow such designs.

HTH.




William L. Polhemus, Jr. P.E.
Polhemus Engineering Company
Katy, TX, USA
Phone (281) 492-2251
FAX (281) 492-8203
email bill(--nospam--at)polhemus.cc

-----Original Message-----
From: Amy Ellis [mailto:EllisAL(--nospam--at)c-b.com]
Sent: Thursday, February 28, 2002 1:12 PM
To: seaint(--nospam--at)seaint.org
Cc: Greg Creamer; Darrell Thompson; vkimm(--nospam--at)hdrinc.com
Subject: RE: STRUCTURAL STEEL: Large Pipe Column?

Bill,

I am working on a project for the new Terminal out at DFW Airport.  DFW
specifies HSS 16x16 tubes for all overhead signs.  I was wondering about
your statement regarding not using rectangular tubes in the state of Texas
due to fatigue.  Could you elaborate on this point or let me know where to
look to find out more information.



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*   Association of Southern California (SEAOSC) server. To
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*
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*   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
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