Foundation failure

Inertia-induced overturning moments generate increased compression and possibly tension forces in the end columns of a moment or braced frame and in the chords of a shear wall (Fig. 7.1). If the foundations have been under-designed for the magnitude of those forces, foundation

▲ 7.7 Foundation settlement of up to 500 mm contributed to the building damage. 1999, Izmit, Turkey earthquake.

(Sezen, H. Courtesy of the National Information Service for Earthquake Engineering, EERC, University of California, Berkeley).

failure occurs. Footings or piles fail when they are pushed excessively into the soil and displace the soil around them (Fig. 7.7). Piles can be pulled from the soil as a building topples over.

It is possible for some buildings to survive an earthquake by rocking. Once a building starts to rock, its natural period of vibration increases and this reduces its acceleration response. Sometimes, especially in shear wall buildings requiring seismic retrofitting, the acceptance of, and design for foundation rocking justifies less invasive strengthening. The Hermès building in Tokyo has been designed to rock, as explained in Chapter 2.

Engineers prevent foundation failure by assessing levels of design forces and sizing the foundations accordingly. The safest method of foundation design uses the Capacity Design approach. Foundation failure is avoided if foundations are designed stronger than the structural fuses in superstructure members.

▲ 7.7 Foundation settlement of up to 500 mm contributed to the building damage. 1999, Izmit, Turkey earthquake.

(Sezen, H. Courtesy of the National Information Service for Earthquake Engineering, EERC, University of California, Berkeley).

Was this article helpful?

0 0
Greener Homes for You

Greener Homes for You

Get All The Support And Guidance You Need To Be A Success At Living Green. This Book Is One Of The Most Valuable Resources In The World When It Comes To Great Tips on Buying, Designing and Building an Eco-friendly Home.

Get My Free Ebook


Post a comment