Damping coefficients for ground types (seismic engineering)

[graduatequestions]

Can anyone explain to me/point me in the direction of some good resources on damping coefficients for different ground types?

I know the waves propegate differently through different material & if you are on a soft ground your loading will be more severe than if you were on rock...and that say if you are on a hill the loading will be more onorous but i'm not sure how to calculate the effect of any of these aspects!

Any help would be appreciated!

 

[graduatequestions]

Nobody got any pointers on this?

 

[dgillette]

What are you looking for, concepts, specific values, or what? Linear analysis, equivalent-linear analysis, or non-linear with permanent strain allowed? One graduate-level 3-semester-hour course would cover most of it, and like so many other things in geotechnical engineering, explanations and answers are extremely context dependent. For example, what's the Young's modulus of steel? 29,000,000 psi. What's the Young's modulus of sand? Depends on grain-size distribution, grain shapes, density, confining stress, method of compaction, plane-stress vs plane-strain vs triaxial, direction of loading w.r.t. anisotropy, loading s unloading or reloading, amount of strain, and probably something else I haven't thought of. In other words, things that don't lend themselves to one-sentence answers. Damping would be similar.

Anyway...If it's for concepts and the math, because I have it handy, I use "Soil Dynamics" by Tien Hsing Wu, originally published by Allyn and Bacon in 1971, then self-published in 1975. Not sure how easy it is to find. I haven't read it, but you might try Steven Kramer's book on earthquake engineering of dams, which probably has good info on response analysis, which would have include strain-dependent damping, modulus reduction, and all that stuff; and a dam is kind of like a hill.

The hill will quite likely require a 2-D analysis (QUAD4M, QUAKE/w, FLAC, PLAXIS), not 1-D (SHAKE).