Transferring Earth Loads thru Rigid Diaphragms at Exposed Basement
Transferring Earth Loads thru Rigid Diaphragms at Exposed Basement
(OP)
I have a building roughly 300’ x 175’. It is built into a hill. There is a concrete foundation wall between the basement slab and the first floor. Between the first and second floor, the north and west walls are concrete and built into the hill. The south and east walls are mostly exposed (at grade). The floor construction at both elevated floors is concrete topped precast plank supported by steel beams and columns. The second floor is at grade at the north and west elevations. It is steel columns and girders and bar joist girders. The roof is metal deck.
They will be backfilling after the floors are in place, because against my better judgment they do not want the expense of counterfort retaining walls. I am incredibly concerned about unbalanced earth pressure particularly the ability to transfer it through the diaphragm at the first floor. I know I’m going to need to dowel the concrete topping to the foundation wall to help transfer shear. Any words of advice as to what else I might need to consider? Should I be considering passive pressure on the single story basement wall?
They will be backfilling after the floors are in place, because against my better judgment they do not want the expense of counterfort retaining walls. I am incredibly concerned about unbalanced earth pressure particularly the ability to transfer it through the diaphragm at the first floor. I know I’m going to need to dowel the concrete topping to the foundation wall to help transfer shear. Any words of advice as to what else I might need to consider? Should I be considering passive pressure on the single story basement wall?






RE: Transferring Earth Loads thru Rigid Diaphragms at Exposed Basement
RE: Transferring Earth Loads thru Rigid Diaphragms at Exposed Basement
Be sure you also include the seismic loading on the retaining wall and take that wall reaction into the diaphragm.... This load can be huge. Be sure you have a soils report and they tell you what loading to use.
RE: Transferring Earth Loads thru Rigid Diaphragms at Exposed Basement
If I consider at rest pressure everywhere, I have a net force of about 14 klf that needs to go into the diaphragm.
RE: Transferring Earth Loads thru Rigid Diaphragms at Exposed Basement
You don't indicate what load you are designing for, but remember that if the wall on the high side doesn't move, then the applied load will be at-rest (not active). Also, make sure to account for any water pressure that may develop on the uphill side.
Mike Lambert
RE: Transferring Earth Loads thru Rigid Diaphragms at Exposed Basement
Also I'm curious what others would say about designing the walls for at-rest pressures but checking stability with active pressures. i.e. if the structure is going to overturn it needs to move.
EIT
www.HowToEngineer.com
RE: Transferring Earth Loads thru Rigid Diaphragms at Exposed Basement
EIT
www.HowToEngineer.com