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RE: UBC 97 - SEISMIC DESIGN GRANULAR SILOS[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: seaint(--nospam--at)seaint.org
- Subject: RE: UBC 97 - SEISMIC DESIGN GRANULAR SILOS
- From: "Harold Sprague" <spraguehope(--nospam--at)hotmail.com>
- Date: Thu, 16 Feb 2006 15:59:35 +0000
Stefan,Given your constraints, treating the silos as nonstructural components per section 1632 should result in a more conservative design.
I just get nervous when I see the UBC zones being used. There were many significant changes in the transition to the IBC. Studies have shown that you can be very far off with base shear calculations when compared to using seismic specral ordinates.
It might be worth a little extra time and see how your design would look if you used the ASCE 7-05. You don't have to tell your client, but it would be an intersting check.
It is worth noting that the Veletsos paper is about the best document that there is on seismic design of silos and bins containing granular material.
Another good document for reference is Tubular Steel Structures by Troitsky. But the Veletsos paper is what should be used for seismic design.
Regards, Harold Sprague
From: "Stefan Reumers" <Reumers.S(--nospam--at)ellimetal.com> Reply-To: <seaint(--nospam--at)seaint.org> To: <seaint(--nospam--at)seaint.org> Subject: RE: UBC 97 - SEISMIC DESIGN GRANULAR SILOS Date: Thu, 16 Feb 2006 09:01:44 +0100 Thanks Harold, The thing about UBC'97 not being the most appropriate code for calculating silos is exactly what I told our client but he would not listen. So I am stuck with this code. The discussion now is wether or not to use section 1632. However trying to keep the wall-thicknesses of the silos within realistic limits, I proposed to apply the Veletsos, Younan and Bandyopadhyay-report (Dynamics of solid-containing tanks, prepared for the department of energy, Washington, D.C.). This report allows for a part of the horizontal force to be transferred to the bottom (in our case the cone-cylinderjunction of the silo) through intergranular friction. For those who are interested in this report, it can be downloaded here : http://www.osti.gov/bridge/purl.cover.jsp?purl=/453784-sUxqbN/webviewabl e/ This report also formed the base for parts of the new Eurocode 8 Part 4 (Design of structures for earthquake resistance - Silos, tanks and pipelines). If any-one has experience with this method of design please let me know. Kind regards Stefan Reumers -----Original Message----- From: Harold Sprague [mailto:spraguehope(--nospam--at)hotmail.com] Sent: woensdag 15 februari 2006 20:31 To: seaint(--nospam--at)seaint.org Subject: RE: UBC 97 - SEISMIC DESIGN GRANULAR SILOS It sounds like this is an attempt to use importance factors and the 1997 UBC to achieve a perceived higher performance. I would suggest that you use a more up to date code like the ASCE 7-05 and perform a more sophisticated analysis. Conservatism on loads does not necessarily buy you better performance. Applicability of the UBC 97 to properly design granular silos is a reach. There were some adjustments made in the NEHRP that have been reflected in the ASCE 7-05. I would urge you to look at the ASCE 7-05 section 15.3.1 and 15.3.2 which had granular silos in mind when it was created. It was in the ASCE 7-02 as well. Further, there has been coordination between nonstructural components and nonbuilding structures in the NEHRP / ASCE / IBC process to try to account for this as much as possible. Not much was included in the UBC 97. This was in the early days of the nonbuilding structures effort. I would look at the relative stiffnesses of the aluminum silos and the concrete support structure. I would also treat the contained product as just an impulsive mass. We have looked at the potential of a convective component but there is not enough data. Regards, Harold Sprague > >-----Original Message----- >From: Stefan Reumers [mailto:Reumers.S(--nospam--at)ellimetal.com] >Sent: Wednesday, February 15, 2006 6:58 AM >To: seaint(--nospam--at)seaint.org >Subject: UBC 97 - SEISMIC DESIGN GRANULAR SILOS > > > >I have to design 24 aluminium silos 720 m3 each for the storage of granular >Polyethyleen. > >These silos are mounted on a 20 m high concrete structure. > > > >Prescribed earthquake code is UBC '97. > > > >Does Section 1632 apply or can I use Sections 1634 together with Section >1630 ? > >This makes quite some difference in the total lateral force. > > > >In addition, our customer asks for an importance factor of 1,50 as to my >opinion granular storage silos would only require an importance factor of >1,0. > > > > > >Any help would be much appreciated > > > > > >Stefan Reumers > >Engineering Silo Dept. > >Ellimetal nv >
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- RE: UBC 97 - SEISMIC DESIGN GRANULAR SILOS
- From: Stefan Reumers
- RE: UBC 97 - SEISMIC DESIGN GRANULAR SILOS
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