Need a book? Engineering books recommendations...

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

RE: Shear Key in Basement walls

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Jake:

I am kinda confused on the shear friction concept. I agree that one can use shear friction to transfer the active soil pressure from the stem wall to the base slab. Part of that load can be transferred to the foundation through friction between the base slab and the foundation. But what about the base slab itself - what do you design that for ? I would appreciate a clarification on process you use - especially the base slab design.

PS: The retained earth is 9 feet. This is a residence. I do not have the building dimensions off hand - the building is at least 40 feet wide x 100 feet long.

Gautam


From: "Jake Watson" <jwatson(--nospam--at)utahisp.com>
Reply-To: <seaint(--nospam--at)seaint.org>
To: seaint(--nospam--at)seaint.org
Subject: RE: Shear Key in Basement walls
Date: Fri, 11 Jul 2003 08:24:05 -0600

If this a standard house and you have reinforced the walls, shear friction
should do the trick. Then you won't have to worry about a fancy analysis to
justify it.

Jake Watson, P.E.
Salt Lake City, UT
  -----Original Message-----
  From: Tripp Howard [mailto:tripphoward(--nospam--at)yahoo.com]
  Sent: Friday, July 11, 2003 6:45 AM
  To: seaint(--nospam--at)seaint.org
  Subject: Re: Shear Key in Basement walls


  Just curious how many people use shear keys.  I've moved away from them
since they can be hard to form and make installing waterstops difficult.  I
typically just roughen the surface between the wall and the footing and
check it with the shear friction provisions.  What do others think about
doing it this way?

  On another note, I've gone away from using the traditional rubber
waterstops due to the difficulty in installing them properly.  If I need a
waterstop, I've been using a swellable hydrophilic waterstop such as
Volclay's Waterstop RX. You can adhere it to roughened surfaces and to join
ends you just but them together.  No welding or special glues required.
What are others opinions on these alternate types of waterstops?

  G M <newabhaju(--nospam--at)hotmail.com> wrote:
    To all:

I recently designed a basement wall as a cantilever retaining wall with
a
    shear key. The slab within the two ends of the retaining walls is a 5
inch
    slab on grade. Due to field condition, the contractor does not want to
    intstall the shear keys.

One way to reduce the shear demand at the base of the retaining wall is
to
account for the fact that the first floor provides some lateral support.
    However, because the first floor consists of wood construction, I am
hesitant to do this and prefer to be conservative. ( I do reinforce the
wall
    stem for this condition,though).

    The second alternative is to assume that the active force on the
retaining
    wallls at the opposite ends of the basement cancells each other out -
therefore, a shear key is not necessary. This condition should hold true
no
    matter how far the two retaining walls are located - in finite terms,
thoguh
    - provided they are of the same height and have simillar backfill. The
slab-on-grade will be subjected to compressive forces from the retaining wall and should act as a plate with compressive forces on all four sides
(
    four sides of the basement).

My question to you all is - how do you design the slab? I am thinking of
    taking a unit width of slab and finding the allowable compressive load
based
    on Euler's formula with a factor of safety. Since water will be
drainded,
    moment due to water pressure should not be an issue.

    If the wall design were to include seismic forces - (Mononobe-Okabe
equation)- how would one dissipate the shear for the worst case scenario
for
seismic forces acting in the same direction for the two opposite walls.

    Your comments would be highly appreciated.

    Gautam

    _________________________________________________________________
    Add photos to your e-mail with MSN 8. Get 2 months FREE*.
    http://join.msn.com/?page=features/featuredemail


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

  Tripp Howard


----------------------------------------------------------------------------
--
  Do you Yahoo!?
  SBC Yahoo! DSL - Now only $29.95 per month!

_________________________________________________________________
Tired of spam? Get advanced junk mail protection with MSN 8. http://join.msn.com/?page=features/junkmail


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