single footing, biaxial bending,soil tension! Adjust pressure? 2

[IJR]

Pals

Occassionally I have footings with double bending and tension on some corners.

I usually model these using stiff springs and get rid of springs that have tension in them.

I usually end up with some area in compression, which I keep at about 75% of total area minimum(on fear of overturning)

Is there any manual method or any useful software that iteratively makes the foundation compression only?

respects

ijr

 

[Ron]

Change the stiffness of the springs in the primary contact area to accommodate increases in soil displacement (elastic compression)due to higher loading in the center of the footing. This should bring the corner conditions closer to compression.

Keep in mind that you might actually have a condition where you lose contact due to bending. Primarily occurs when there is a high moment on the footing.

 

[kslee1000]

I think several commercial structural programs such as STAAD, RISA are now capable of handling this situation by using the commend - compression spring support in the analysis.

 

[BAretired]

There was a similar discussion recently at:

http://www.eng-tips.com/viewthread.cfm?qid=236147

BA