Seismic Loads Due to Soil (Basement)
Seismic Loads Due to Soil (Basement)
(OP)
We are designing a commercial building that has a walk-out basement. Are there seismic loads due to the soil behind the walls that we have to take into consideration?
I checked ASCE-7-05 and I could not find anything. Chapter 19 made no sense to me at all.
I checked ASCE-7-05 and I could not find anything. Chapter 19 made no sense to me at all.






RE: Seismic Loads Due to Soil (Basement)
RE: Seismic Loads Due to Soil (Basement)
From the CBC/IBC: (similarly in ASCE 11.8.3)
1802.2.7 Seismic Design Category D, E or F. Where the
structure is determined to be in Seismic Design Category D,
E or F, in accordance with Section 1613, the soils investigation requirements for Seismic Design Category C, given in Section 1802.2.6, shall be met, in addition to the following.
The investigation shall include:
1. A determination of lateral pressures on basement and
retaining walls due to earthquake motions.
RE: Seismic Loads Due to Soil (Basement)
Is there a code reference for this?
RE: Seismic Loads Due to Soil (Basement)
1) Analytical (models with springs or with forces and springs) - Watch the attach as an example
2) FEM Model (you should model the structure-soil interaction with non-reflecting boundaries), is the most accurate solution but takes more time.
Analytical:
You need to calculate the deflection of a soil column subjected to the EQ, and then assume that the structure has the same deflection because the move together. And then according with the stiffness of the structure you can obtain the member forces.
FEM Model:
You have to model the structure, the soil (3H to each side, 2H deep, where H is the structure height), and the interaction between them. It's very important the boundary conditions that you addopt. A non-reflection boundary is the best solution, because them doesn't reflect the seismic waves. Bye,
Sebastian
RE: Seismic Loads Due to Soil (Basement)
RE: Seismic Loads Due to Soil (Basement)
As I know, there is no such code that directly covers this issue, however, ASCE7-05 session 15.7.9.3.1 (page 171) covers the issue of increased lateral pressure of granular material on tank walls during seismic shaking, I think this is a good reference. Besides, this is an educated logic deduction. I have used it in designing in several of my previous projects.
RE: Seismic Loads Due to Soil (Basement)
RE: Seismic Loads Due to Soil (Basement)
Can you give me a code reference for that?
Berniedog
RE: Seismic Loads Due to Soil (Basement)
Do a google search and you will find good material on it.... as well as here in these forums.
RE: Seismic Loads Due to Soil (Basement)