INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Jobs

Determination of Lateral Capacity of Piles for Bridge Foundation

Determination of Lateral Capacity of Piles for Bridge Foundation

(OP)
I am currently redesigning a 3 span, single lane bridge. According to my calculations, the bridge is failing due to sliding, but I have not considered the lateral capacity of the pile (2 rows of 6 piles each) as a part of the resisting forces. I would like to include these in order to avoid increasing the dimensions of the footing, but the soil geotechnical report does not provide these values. Is there a way that I can estimate this? Also, should I consider the piles acting together as one unit or individually?

The piles are concrete (.3m x .3m) spaced at 1.36m apart center to center. The soil at the tip of the pile is considered to be "dense to very dense gray coarse gravel"

Thank you

RE: Determination of Lateral Capacity of Piles for Bridge Foundation

You need to do a lateral analysis of the foundation piles and pile cap. Usually, the geotech will do this using LPile or AllPile.

www.PeirceEngineering.com

RE: Determination of Lateral Capacity of Piles for Bridge Foundation

Both programs use Com624 for the lateral analysis.

www.PeirceEngineering.com

RE: Determination of Lateral Capacity of Piles for Bridge Foundation

Also, competent soil near the top of the pile is more effective for providing lateral resistance than competent soil near the pile tip.

www.PeirceEngineering.com

RE: Determination of Lateral Capacity of Piles for Bridge Foundation

(OP)
PEinc,

Thank you for your response. Unfortunately, I do not have access to this software, and I am unable to get this information from the geotech consultant. The bridge is actually located in Cambodia, and many of the consultants used for the project are difficult to contact. Is there any method for conservatively estimating the lateral capacity of the piles without the use of software? I found some specs used in India, which require calculating the force needed to displace the pile by 5mm, and using this force as the lateral capacity. This method requires analyzing the pile as a cantilever and determining the point of fixity of the pile. Unfortunately, I also do not know how to determine the point of pile fixity, but was assuming that approximating ~1/3 of the pile length would be sufficient. Do you have any further recommendations? Thank you again.

The soil characteristics are as follows:
firm brown silty clay (2m)
loose brown, yellow silty fine to coarse sand (4.5m)
medium dense light-gray clayey coarse sand (1.5m)
stuff yellow, gray silty clay (1.5m)
dense to very dense gray coarse gravel (6m)
*pile length is 10m

RE: Determination of Lateral Capacity of Piles for Bridge Foundation

I believe that COM624 is a free download from FHWA. Without this software, you could possibly design the bearing piles for the lateral load as very short, cantilevered soldier beams that are laterally supported by passive resistqance. This will give you the piles'bending stress and structural steel deflection but not soil movement. This isn't as accurate as using LPile or AllPileb but is better than no analysis. You may also want to check NAVFAC DM-7. There probably is graphical info in there on lateral resistance of bearing piles. DM-7 is also a free download.

www.PeirceEngineering.com

RE: Determination of Lateral Capacity of Piles for Bridge Foundation

Do a google search for "Duncan and Evans" + lateral loading of piles. They developed charts and equations for the same P-Y analyses that LPile uses.

RE: Determination of Lateral Capacity of Piles for Bridge Foundation

Yes, DM-7.02 has a graphical procedure beginning on Page 7.2-234 in my copy. I used to use it before we got L-Pile.

RE: Determination of Lateral Capacity of Piles for Bridge Foundation

(OP)
Thank you all for your help. I actually found the following document used in India, which was fairly easy to use for anyone else having a similar issue (the cover page is also quite catchy):

https://law.resource.org/pub/in/bis/S03/is.2911.1....

As a side note, unfortunately, FHWA no longer has COM624 available for download.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close