Hydrostatic Uplift Vs Column Gravity Loads

[concrete12]

Hi All,

My current problem is that my column gravity loads (only self weight of the structure multiplied by a factor of 0.9) is less than the hydrostatic uplift (multiplied by a factor of 1.2). This is only problematic for one column.

When designing my hydrostatic slab (reinforced concrete), I have modelled all columns (aside from the problem column) as supports and modelled the problem column as a point load (acting in the opposite direction as the hydrostatic uplift). I was wondering what deflection I should be limiting the hydrostatic slab to at the location of the problem column as this column acts as a support for the 7 floors above the hydrostatic slab. Can anyone also advise where I can find this information in the Australian standards?

 

[XR250]

Wait, you have enough buoyancy to float 7 stories?

 

[concrete12]

Hi XR250,

Yes the hydrostatic pressure for one specific column is larger than the dead load (self weight ) carried by the column. All other columns carry enough load.

Please note that the column without enough dead loads becomes an edge column, so it has a larger tributary area on the basement floor which attracts more hydrostatic pressure.

 

[1503-44]

How can you attract more hydrostatic pressure?

--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[HTURKAK]

As far as i understand , you modelled the raft slab supported by columns and loaded with hydrostatic uplift. Is this true ?

In this case the soil stress under subject column is not positif and uplift would develop then the raft probably will tilt ..

Will you post some more info . to understand the situation ?









I cannot give you the formula for success, but I can give you the formula for failure..It is: Try to please everybody.

 

[manstrom]

Can you add concrete mass to create higher DL?

 

[JLNJ]

Shouldn't it be 1.6*H rather than 1.2?