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RE: IBC 2006 - SEISMIC DESIGN OF STEEL - 2205.2.2[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: <seaint(--nospam--at)seaint.org>
- Subject: RE: IBC 2006 - SEISMIC DESIGN OF STEEL - 2205.2.2
- From: Harold Sprague <spraguehope(--nospam--at)hotmail.com>
- Date: Sat, 21 Feb 2009 22:19:43 +0000
The R factor is intended to indicate the level of performance intended. If you drop the R value low enough, you are approaching an elastic response. As such, inelastic behavior as required by higher R factors, is not necessary. The inelastic behavior of concentric braced frames happens in the connections for systems such as the SCBF. |
When we created the nonbuilding structures section in the mid 1990's, it was an effort to address issues such as these. There was an effort to eliminate OCBF's for buildings. We needed to retain them for nonbuilding structures such as large electric power plant boiler buildings. The SCBF's were not practical. And the decision to preclude them from building structures was not well grounded. We made a considered decision to allow OCBF in trade for lower R values which created higher demand. With the implied linear response, we were justified in deleting the ductility requirements as contained in the SCBF section.
The only reason that I brought up structures with no gussets was to exemplify that we do not necessarily need to develop ductility in the gussets. We still have the intended code structural performance with structures that do not meet the ductility requirements.
Regards, Harold Sprague
Subject: Re: IBC 2006 - SEISMIC DESIGN OF STEEL - 2205.2.2
Date: Sat, 21 Feb 2009 08:19:03 -0600
Problem: virtually all our connections involve gussets. What then?
William L. Polhemus, Jr. P.E.
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On Feb 21, 2009, at 1:25 AM, Harold Sprague <spraguehope(--nospam--at)hotmail.com> wrote:
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