Lateral Resistance to EQ

[NHstructural]

I have been reading a lot of codes lately and seem to recall something that I can't find again. I thought I read that I could not rely on soil friction for lateral resistance to a seismic event. I really don't want to have to use rock anchors.

I doubt my memory so maybe someone can definitively tell me I am wrong or right and alert me to where I might have found it. If I did in fact read it, I suspect it was either in IBC 2006 or 2003, ASCE7-05, or even ACI 318-02.

Thanks for your thoughts.

 

[shin25]

Look at the PCI design hand book 6th edition. The examples use soil friction to resist lateral forces. (These examples contradict your statement)

 

[whyun]

Seismic base shear may be resisted by soil friction, passive pressure or combination thereof. Geotechnical engineer may prohibit soil friction for certain site conditions including areas with liquefaction potential.

 

[JAE]

See table 1804.2 in the IBC. It implies that lateral sliding is possible with seismic loads (see the footnotes).

However, be sure, in your load combinations, to take into account the vertical component of seismic demand as this will reduce the friction amount.