# Re: Footing sliding resistance - Friction

• To: seaint(--nospam--at)seaint.org
• Subject: Re: Footing sliding resistance - Friction
• From: Daryl Richardson <h.d.richardson(--nospam--at)shaw.ca>
• Date: Mon, 20 Jun 2005 13:23:52 -0600
```Christopher,

```
The coefficient of friction of 0.45 simply means that 45% of the vertical load can be relied upon to resist lateral loading. This is not related to the width of footing, HOWEVER, the weight of footing can also be included in the vertical load as can the weight of backfill on top of the footing. As a result, increasing the footing width will also increase the weight resisting the loading.
```
Regards,

H. Daryl Richardson

```
----- Original Message ----- From: "Christopher Haffner" <chaffner(--nospam--at)gorge.net>
```To: <seaint(--nospam--at)seaint.org>
Sent: Monday, June 20, 2005 12:50 PM
Subject: Footing sliding resistance - Friction

I'm having a Monday morning brain freeze and thought this was a no-brainer
but can't find a definitive answer.

I am being told by the Geologist on a sloping (2H:1V) residential lot that
the coefficient of friction is .45 (no units).  He is also indicating that a
wider footing will add some needed resistance to sliding.

I don't think this is correct in that the coefficient should only depend on
the amount of gravity (vertical) load and not on the area of the bearing
area.  Therefore, making my footings wider won't really help my sliding
problem other than to add a little more weight.  Am I thinking clearly here?

Another question.......I will have some granular fill (varies from 1' to 6'
thick) below a basement floor slab.  I think this helps my sliding
resistance by adding weight to the system as it interfaces with the soil
below.  Since I am having the slope benched I would like to use this
resistance (weight x coef of frict).  Opinions????????

Chris

Haffner Consulting Engineering
www.haffnerconsulting.com
Office & Fax:  541-478-3052

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