Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

RE: Load factor for Cooling Tower

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Dear Harold,
Thanks a lot for your lengthy mail. The cooling tower which I am
designing is at an elevated level so sulphates are not a major issue
except for foundations.
As you suggested I will consider long term serviceability issues as per
ACI 350.
Regards
Ashraf

-----Original Message-----
From: Harold Sprague [mailto:spraguehope(--nospam--at)hotmail.com] 
Sent: 11 September 2006 19:04
To: seaint(--nospam--at)seaint.org
Subject: RE: Load factor for Cooling Tower

Ashraf,
The only ignorance is to NOT ask the question.  And this is a good
question!

ACI 350 is specifically written for environmental structures.

>From the Scope section of ACI  350:
"The code portion of this document covers the structural design,
materials 
selection, and construction of environmental engineering concrete 
structures. Such structures are used for conveying, storing, or treating

liquid, wastewater, or other materials, such as solid waste. They
include 
ancillary structures for dams, spillways,and channels.

They are subject to uniquely different loadings, more severe exposure 
conditions and more restrictive serviceability requirements than normal 
building structures. Loadings include normal dead and live loads and 
vibrating equipment or hydrodynamic forces. Exposures include
concentrated 
chemicals, alternate wetting and drying, and freezing and thawing of 
saturated concrete.

Serviceability requirements include liquid-tightness or gas-tightness. 
Typical structures include conveyance, storage, and treatment
structures. 
Proper design, materials, and construction of environmental engineering 
concrete structures are required to produce serviceable concrete that is

dense, durable, nearly impermeable, resistant to chemicals, with limited

deflections and cracking. Leakage must be controlled to minimize 
contamination of ground water or the environment, to minimize loss of 
product or infiltration, and to promote durability.

This code presents new material as well as modified portions of the ACI 
318-95 Building Code that are applicable to environmental engineering 
concrete structures."

>From the load factor section of ACI 350 the commentary reads:
"R.9.2.5 - This section addressees the need to consider loading due to 
weight of fluid or fluid pressure. Although fluid densities and heights
are 
usually well known, the load factor of 1.7 is used as a part of the
concept 
of environmental durability and long-term serviceability of the
structure."

Obviously a cooling tower is NOT an environmental structure.  However,
if 
you wish to consider long term serviceability, you should consider using
the 
crack limits and load factors contained in ACI 350.  Until the cooling
tower 
people develop a code of their own there is not much guidance.

In your area of the world, you have an issue with sulfates in the water
and 
soil.  Sulfates are a major serviceability issue.

Regards,
Harold Sprague





>From: "Ashraf, Mohammed (Qatar)" <mohammed.ashraf(--nospam--at)worleyparsons.com>
>Reply-To: <seaint(--nospam--at)seaint.org>
>To: <seaint(--nospam--at)seaint.org>
>Subject: Load factor for Cooling Tower
>Date: Mon, 11 Sep 2006 09:23:16 +0300
>
>Dear fellow engineers,
>
>I am designing a cooling tower. I have some doubt regarding the load
>factors to be used.
>
>For  fluid load (F), ACI 350-01 says U=1.4D+1.7F. But ASCE-02, says
>1.4(D+F). Which load combination to used for cooling tower basin
>design?.
>
>Ignorance is regretted.
>
>Thanks in advance,
>
>Regards,
>
>Ashraf
>

_________________________________________________________________
Search from any web page with powerful protection. Get the FREE Windows
Live 
Toolbar Today!   http://get.live.com/toolbar/overview


******* ****** ******* ******** ******* ******* ******* ***
*   Read list FAQ at: http://www.seaint.org/list_FAQ.asp
* 
*   This email was sent to you via Structural Engineers 
*   Association of Southern California (SEAOSC) server. To 
*   subscribe (no fee) or UnSubscribe, please go to:
*
*   http://www.seaint.org/sealist1.asp
*
*   Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you 
*   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 
******* ****** ****** ****** ******* ****** ****** ******** 
*** WORLEYPARSONS GROUP NOTICE ***
"This email is confidential.  If you are not the intended recipient, you must not disclose  or  use the  information contained in it.  If you have received this email in error,  please notify us immediately by return email and delete the email and any attachments. Any personal views or opinions expressed by the writer may not necessarily reflect the views or opinions of any company in the WorleyParsons Group of Companies."


******* ****** ******* ******** ******* ******* ******* ***
*   Read list FAQ at: http://www.seaint.org/list_FAQ.asp
* 
*   This email was sent to you via Structural Engineers 
*   Association of Southern California (SEAOSC) server. To 
*   subscribe (no fee) or UnSubscribe, please go to:
*
*   http://www.seaint.org/sealist1.asp
*
*   Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you 
*   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 
******* ****** ****** ****** ******* ****** ****** ********