Tom is on target as usual.
It was never the intent to discourage the use of the formulas in API or AWWA. The intent of the NERHP and the ASCE 7 was to foster updating to the more current ground motions and to present equations on how to employ the new ground motions. As the API and AWWA have developed, the NEHRP and ASCE have referenced those documents.
In the future, the NEHRP will represent more of the cutting edge of code development using the ASCE 7 as the base. You will also find the NFPA 59A currently provides some information regarding vertical seismic ground motions not present in the current codes, but can drive the design of liquid containing structures especially in areas of close proximity to thrust or subduction faults.
Regards,
Harold Sprague
To: seaint@seaint.org
Subject: Re: Fundamental period of tanks
From: Tom.Hunt@fluor.com
Date: Thu, 27 Dec 2007 12:43:59 -0800
Dave,
From API 650, the first mode sloshing wave period (Tc), in seconds, is taken from the below formula:
Tc = Ks x square root of D
Ks = 0.578 / square root of tanh(3.68H/D)
Thomas Hunt, S.E.
Fluor
"Dave Adams" <davea@laneengineers.com>
12/27/2007 12:04 PM
Please respond to seaint
<seaint@seaint.org> Fundamental period of tanks
Hello everyone,
Those of you who deal with non-building structures: How are you spending your time determining the fundamental period of flat-bottom tanks (T-sub-i in ASCE 7-05, Section 15.7)? Are you actually modeling and calculating the value or using simplified equations from material standards (i.e. AWWA or API)? ASCE 7 appears to really discourage the use of simplified equations.
Thanks,
Dave K. Adams, P.E., S.E.
LANE ENGINEERS, INC.
Tulare, CA 93274------------------------------------------------------------ The information transmitted is intended only for the person or entity to which it is addressed and may contain proprietary, business-confidential and/or privileged material. If you are not the intended recipient of this message you are hereby notified that any use, review, retransmission, dissemination, distribution, reproduction or any action taken in reliance upon this message is prohibited. If you received this in error, please contact the sender and delete the material from any computer. Any views expressed in this message are those of the individual sender and may not necessarily reflect the views of the company. ------------------------------------------------------------
Don't get caught with egg on your face. Play Chicktionary! Check it out!