Bearing pressure of soil from seismic force on column

[apaulos15]

I am analyzing an existing building with several steel moment frames, and was wondering how to approach calcing out the pressure on the soil from the seismic forces on the columns. Each moment frame is on a grade beam 16" wide and 1' deep. Say for a 10' high frame with columns spaced 10' apart, the seismic force is 50 kips, which would put 50 kips of tension/ compression at either column. Any input on any example problems or references is appreciated!

 

[KootK]

Are there no piLes beneath The columns? If not, I'd tFeat your grade beam as a strip footing. It doesn't sound very promising with respect to capacity.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[apaulos15]

There are no piles beneath the columns. Would you be able to give me an example of how to approach this problem if I treat the grade beam as a strip footing?

 

[KootK]

Actually, I rescind my earlier comment. In your scenario, I would not treat it as a strip footing. Strip footings span one way in flexure: the short way. In your situation, I'd approach the design as a very long, narrow conventional spread footing Or beam on elastic foundation. You can find examples of spread footing design in most any foundations textbook or concrete design textbook. There are also good examples in the CRSI Handbook and the Structural Engineering Reference Manual.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.