×
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!
  • Students Click Here

*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.

Students Click Here

Jobs

Eccentically Load Pad Footing Design

Eccentically Load Pad Footing Design

Eccentically Load Pad Footing Design

(OP)
In many design examples from the ACI318 Design Handbook (for footing strength design for Vu, Mu), the values of W or E is given in terms of a concentrically load P and subsequent q is derived (with proper load combinations) yielding a simple q=P/A.  This q is then used to evaluate Vu and Mu and subsequent As and Av.

My question is how can I derive the q in these terms when I have an overturning moment at the footing and essentially an eccentric P?  In some cases, applying 0.9D+E or 0.9D+1.6W, yields 'e' larger than the width of the footing (far beyond B/2) and yet q < Q allowable when evaluating stability of footing.  

Should I just give up trying to figure out what q is and use whatever allowable Q given by the soil engineer or by code since it's a sin to go beyond the Q.

I'd greatly appreciate your thoughts.
 

RE: Eccentically Load Pad Footing Design

You should move your Q to the Structural section if you want anyone to respond.  The BIM section is rarely ever visited.

Brad

RE: Eccentically Load Pad Footing Design

Lttang
for calculating q you have to derive stress equation as following:
q=P/A+MyX/Iy+MxY/Ix. by using this equation you can calculate q in any point and can draw shear and moment diagrams. now you can design footing by calculated stresses. recently i have deisgned a footing which belongs to very big elevated tank and i had the same problem. please let me know if you could not solve your poblem.  

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