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Re: Vertical component of EQ in UBC97 and IBC2000

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Christopher,
Unfortunately, private companies do not like to have "failures" even elemental "failures" published. They depress the stock market. Most of the "seismic structurally challenged structures" (structural political correct speak) were not in the public domain. I will share what I can. One of the companies was a large publicly held aerospace contractor.

I'm real curious about the tank hoop stress failure and the bridge crane failures. Were any reports published?
RE: EERI Northridge Earthquake, January 17, 1994, Reconnaissance Report

Were the tank failures really overstress in the girthwise direction like you'd get with over-pressure or simply side wall failures? This is still debated.

Was the failure mechanism determined?
Elephant's foot was previously viewed as a sloshing failure, but when you actually do the shake table tests, it is fairly rare that you get a sustained motion that can trigger a sloshing wave form. It can be done more easily at greater distances from the source. The buckling occurred along the complete circumference at the base of the tank.

What did the failures look like? Any pictures?
Figure 7.2 EERI Northridge Recon Report

Were the tanks liquid-filled?
Yes

Were the tanks intended to be pressurized or simply gravity tanks
Gravity

Were the tanks horizontally mounted or vertical?
Unanchored mounted on SOG

What sort of supports were used? Did the supports also fail?
Unanchored.  No.

What failed on the bridge cranes? Girders, end trucks, connections?
Nothing until it hit the ground.

Did the structure itself fail or did either the bridge or trolley jump the rails?
Jumped the rails

Were there seismic hold-downs on the bridge or trolley?
No hold downs.

Were the cranes under load at the time?
No

Regards,
Harold Sprague




From: Christopher Wright <chrisw(--nospam--at)skypoint.com>
Reply-To: <seaint(--nospam--at)seaint.org>
To: <seaint(--nospam--at)seaint.org>
Subject: Re: Vertical component of EQ in UBC97 and IBC2000
Date: Tue, 9 Nov 2004 10:47:35 -0600


On Nov 9, 2004, at 10:23 AM, Harold Sprague wrote:

There were some tanks that had hoop stress failures. There were bridge cranes that collapsed.
What a great thread--makes all the political rants worthwhile. I'm real curious about the tank hoop stress failure and the bridge crane failures. Were any reports published?

Were the tank failures really overstress in the girthwise direction like you'd get with over-pressure or simply side wall failures?
Was the failure mechanism determined?
What did the failures look like? Any pictures?
Were the tanks liquid-filled?
Were the tanks intended to be pressurized or simply gravity tanks
Were the tanks horizontally mounted or vertical?
What sort of supports were used? Did the supports also fail?

What failed on the bridge cranes? Girders, end trucks, connections?
Did the structure itself fail or did either the bridge or trolley jump the rails?
Were there seismic hold-downs on the bridge or trolley?
Were the cranes under load at the time?

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/


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