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

RE: EMPIRICAL RELATIONS FOR THICKNESSES.

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Sherman,

Thanx for ur update on the news that the revised report of ACI COMMITTEE 350
is likely to be out soon which will support empirical stipulations spelt out
in FINTEL'S book.

I agree with your approach of design. Me too, do the same thing. From
experience I know, if the depth increases beyond 4-5 m, it is very likely
that shear would govern & dictate the thicknes of the wall, especially.

Actually, I was looking for some references, codal especially, which would
go along with FINTEL'S recommendations. You know, sometimes you have a rush
of the project and you need to proceed with the shop drawings ahead of the
DESIGN. And, these emipirical relations do help you to atleast begin the
drafting work & finalize the same after you have completed the final design;
whereafter you can go back to drafting to revise the details, if there is a
need to.

Also, before you set off for the final design, these preliminary sizing of
the members do help you to get to the final design.

I hope you understand what Iam trying to make my point here.

Any way thanx, for ur time & effort for the same.

Regards,

SYED FAIZ AHMAD


From: "Sherman, William" <ShermanWC(--nospam--at)cdm.com>
Reply-To: <seaint(--nospam--at)seaint.org>
To: "'seaint(--nospam--at)seaint.org'" <seaint(--nospam--at)seaint.org>
Subject: RE: EMPIRICAL RELATIONS FOR THICKNESSES.
Date: Mon, 28 Jan 2002 10:16:21 -0500

The 1974 edition of Fintel's Handbook suggested thickness to span ratios of
1/12 for cantilever elements and 1/16 for propped cantilever elements. ACI
350 has drafted a document for "Design Considerations for Environmental
Engineering Concrete Structures" which will likely note these as reasonable
rules of thumb to start with. (This document is still in the committee
voting process.) The new ACI 350 code due out "any time now" will require a
minimum thickness of 12-inches for walls 10 ft or greater in height and in
contact with liquids (Section 14.6.2). You aren't likely to find "empirical
relationships" for design in ACI codes and standards since they are
intended
to address minimum final design requirements rather than preliminary or
approximate methods.

I generally check minimum thickness required for shear first and then
required area of steel at point of maximum moment. I try to avoid bar sizes
greater than #8 bars in uniformly reinforced slabs and walls. Fintel's'
Handbook also suggests that a 1% reinforcement ratio generally provides
economical structures.

> -----Original Message-----
> From: syed faiz ahmad [mailto:syedfaiz23(--nospam--at)hotmail.com]
> Sent: Sunday, January 27, 2002 12:15 PM
> To: seaint(--nospam--at)seaint.org
> Subject: EMPIRICAL RELATIONS FOR THICKNESSES.
>
>
> Hi there!
>
> PROBLEM:
>
>   - Empirical relations for establishing preliminary
>     thicknesses of:
>
>             - walls
>
>             - bottom/floor slab
>
>
>    in the design of water retaining structures,
>    sanitary structures, swimming pools, etc is
>    required.
>
> AVAILABLE REFERENCES:
>
>   - ACI 350  is silent on the subject, except it
>     suggests a minimum wall thickness of 300 mm
>     (12-in) should be used for depths 3 m
>     (9.84 ft) & above. The reasons forwarded are
>     related to detailing problem due to rebars on
>     both the faces including concrete cover.
>
>   - for slabs, it is silent completely.
>
>   - B.S (British code of practice) in a reference
>     DESIGN OF LIQUID RETAINING CONCRETE STRUCTURE
>     bY: R.D. Anchor, stipulates:
>
>         -  wall thickness = depth/10
>
>         - for slabs, however, it is silent.
>
>   - In yet another reference HANDBOOK OF CONCRETE
>     ENGINEERING by: Mark Fintel, the following is
>     suggested:
>
>         - wall thickness = depth/16
>
>         - slab thickness = span/16
>
>   - In case of wall thickness it looks to be on
>     a lower side as compared to B.S
>     recommendations for the same.
>
>   - But this recommendation in the above
>     reference is not supported by any related
>     documents of ACI.
>
> CONCLUSION:
>
>   - based on others experiences on the subject
>     the following is solicited:
>
>         - the usual empirical relations
>           practised by others.
>
>         - citation of any related references on
>           the subject.
>
> Thanx in advance. Regards,
>
> SYED FAIZ AHMAD; MENGG, MASCE
> SENIOR STRUCTURAL ENGINEER
> SAUDI OGER LTD
> RIYADH, SAUDI ARABIA.
>
>
> _________________________________________________________________
> MSN Photos is the easiest way to share and print your photos:
> http://photos.msn.com/support/worldwide.aspx
>
>
> ******* ****** ******* ******** ******* ******* ******* ***
> *   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
> ******* ****** ****** ****** ******* ****** ****** ********
>

******* ****** ******* ******** ******* ******* ******* ***
*   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
******* ****** ****** ****** ******* ****** ****** ********




SYED FAIZ AHMAD; MENGG, MASCE
SENIOR STRUCTURAL ENGINEER
SAUDI OGER LTD
RIYADH, SAUDI ARABIA.


_________________________________________________________________
Chat with friends online, try MSN Messenger: http://messenger.msn.com


******* ****** ******* ******** ******* ******* ******* ***
*   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
******* ****** ****** ****** ******* ****** ****** ********