Structure with one side retaining soil pressure loads

[mathcadboy]

I am currently designing a two-story concrete structure that is going to be located in a sloping terrain. The owner doesn't want to backfill or cut the land but he wants to make it sorta look like a "basement" (since only one side of the "basement" will have have soil in it).

Anyway, here are my concerns. I would like to know what is the most economical way in designing this kind of structure. I tried letting the concrete moment frame resist the lateral earth pressure loads, but it produces very huge moments in the columns. Is it more advisable to just build a separate retaining wall to hold the soil then build the structure independent on the soil pressures?

and a follow up question, does anyone here knows how to compute the capacity of a CHB block? the owner wants me to check at what level in the wall do we start just placing CHBs. By the way, the height of soil the structure will be retaining would be 3meters (about 1 story)

Thanks in advance to those who can give their insights.

 

[rowingengineer]

i have marked up your second option with where Hokie and I believe you will need return walls, that could be used at shear walls. Please forgive the poor writing as the drawing is black I had to use whiteout.

Withy ou second option you are creating a strong column at the 1.5m height if this column is attached or near the retaining wall. This can be problematic in high earthquake areas as the shear of the slab will be attached to the shorter column.


ANY FOOL CAN DESIGN A STRUCTURE. IT TAKES AN ENGINEER TO DESIGN A CONNECTION.”

 

[hokie66]

RE is correct. The fill between the walls means the individual walls may not need to be as strong in bending, but the global force from the hillside site is not abated. A frame of slab and columns will struggle to deal with this force, and the shear walls are the best approach. I like the first scheme best, as it only requires one full height transverse wall. The slab on the fill should still be designed as suspended, as the fill will settle.

 

[rowingengineer]

Yes I agree, should have mentioned i like the first option over the second, and would also design it as suspended as the fill will settle.

ANY FOOL CAN DESIGN A STRUCTURE. IT TAKES AN ENGINEER TO DESIGN A CONNECTION.”

 

[mathcadboy]

Thanks! I will take everything into consideration. Shear Wall is sounding like the right way to go.

 

[rapt]

2 points on this,

The moments the frame would have to be designed for would be the same as the wall moment if it was a free standing wall. Bttter to take it on larger columns or shear walls would be better still.

Make sure you calculate your forces from the retained material on the structure as full earth pressure, not active earth pressure in this case as it is a fully braced wall!