Regarding Foundation Design 1

[Md Abu Baker Siddik]

Hello Everyone,
i have a query,
if a structure has been designed as "Fixed Base Joint", then can we design the foundation considering only compression / tension force or we need to consider base moment during foundation design?

 

[driftLimiter]

I think you will want to let on a bit more information.

Moments from a fixed base could be resolved into a tension compression couple. But it depends on the details and the foundation type.

 

[jayrod12]

In my opinion, given the current information, fixed base structure means they expect the foundation to provide the fixity at the base of the structure. Therefore it must be designed to resist the moment.

 

[Md Abu Baker Siddik]

Here i have attached onbe sample drawing of telecommunication pole. i am taking about this pole foundation.

 

[wth]

Assuming the fixed base joint is given as a single point, then of course you need to design the foundation so that it can resist overturning from that moment.

 

[WesternJeb]

OP, let's forget about the verbiage from the designer providing forces.

This telecommunication pole is going to be welded all around the base to the base plate. This detail provides rotational restraint, and ergo attracts a moment. This moment must be resisted.

 

[phamENG]

This is a very common structure and the foundations are quite straightforward. Given the generic nature of the question, I would suggest going to your supervisor and asking for assistance getting started on your foundation design. If you have specific issues, then by all means bring those back to us...but going from zero to start should be between you and your boss.

 

[SE2607]

I'm assuming from the sketch that the monopole is attached to a base plate and the base plate is attached to the footing with anchor bolts arranged in a circle. This is not a case of a point moment being applied on a grade beam by a skinny flagpole. Even if it were, the full moment wouldn't be in the footing, unless it was attached at the end of the grade beam. Assuming you've designed the weld connecting the monopole to the base plate, designed the anchors to resist the forces on them and designed the base plate to transfer the forces to the anchor, the forces on the footing are based on the resulting soil bearing pressure less the weight of the footing. You need to draw a free body diagram of the forces on the footing to determine where the maximum moment occurs and its magnitude. That point is likely at or near the anchor bolts nearest the maximum soil bearing pressure.