Basement walls against Earthquake sliding

[bensarengat]

Hello,

I`ve a 10 storey building with 1 + 1/2 basement ( i called that because the top basement just half embeded).
the total embeded height is about 4.5 meter.

i used prestressed driven piles for tower foundation, i`m also put some bored piles in foundation slabs to restrain flood load (some kinda of tension piles).

Now my concern is my building performance against sliding caused by lateral force (earthquake).
someone said that all the lateral force must restained by piles.
that means that my basement wall is built for nothing!

would you like to give me some reference about basement walls part against the building base shears + dynamic earth pressure + surcharge?

thanks,
best regards

 

[333OnlyHalfEvil]

It's been a minute since I've done something like this but the lateral forces acting on your basement walls that would cause sliding to come into play would be coming from the lateral earth pressure, hydrostatic pressure, earthquake pressure, etc. You get all of them and then plug them into the load combinations. For earthquake forces, if I remember right, it's just a simple distributed load with a plf of whatever your earthquake forces are.

Although you can restrain this force with your piles, you can also make use of the slab floor (if you have one) and the floor members. If your basement is 1.5 floors buried then it may become like a cantilever beam problem if you want to do it that way.

The problem I'm having with providing a better reply is that I did excavation shoring and we didn't use earthquake forces so I'm not 100% sure if that's even right but I'm pulling it off the design guide of another project that calculated earthquake forces in that way. For codes we used the Caltrans Trenching and Shoring Manual but I'm not really sure if it applies to you. It might be worth your time glancing through if you've never heard of it and there might be something in there about earthquake forces. Also, this url is a good blog post on the subject: Seismic Lateral Earth Pressure on Basement and Retaining Walls