Building with Earth: Design and Technology of a Sustainable Architecture

136 Earthquake-resistant building

Earthquakes are caused by the movements
of tectonic plates or by volcanic activity. The
world’s most earthquake-prone regions are
shown in 15. 3. In Asia, earthquakes with
intensities of 8 on the Richter scale have
been recorded; in the Andes, ones measur-
ing up to 8.7. Annually, nearly a hundred
earthquakes are recorded with intensities
above 6, and twenty with intensities above
7 on the Richter scale. Several thousand
people are affected by earthquakes every
year.
Buildings are mainly struck by the horizontal
acceleration created by the movement of
the earth. The vertical accelerations created
by seismic activity are less then 50% of the
horizontal ones.
Since loam buildings are rarely higher than
two storeys, this section mainly discusses
the earthquake resistance problems of these
kinds of buildings.
In one- or two-storeyed buildings, the prin-
ciple danger during earthquakes is that
walls will fall out and roofs will come down.

Therefore, one of the main structural tasks

when designing earthquake-resistant build-

ings is to insure that walls do not fall out.

Structural measures

When designing for earthquake-prone

zones, it should be considered that the seis-

mic forces acting on a building are propor-

tional to its mass, and that deflection

increases significantly with height. When

designing two-storeyed buildings, therefore,

it is advisable that the ground floor be built

solid, while the upper floor is kept light,

preferably with a flexible framed structure.

Heavy roofs with slabs, slates and tiles

should be avoided in principle.

Walls usually fall outwards because they lack

a closed ring beam, sufficient bending and

shear strength, and because door and win-

dow openings weaken the wall structure.

Under seismic influences, forces are concen-

trated into the corners of these openings,

creating cracks. In order to reduce the dan-

ger of collapse, the following points should

be kept in mind:

1. Houses should not be located on inclined
   sites (15. 4).


2. The building’s resonant frequency should
   not match the frequency of the earth move-
   ment during earthquakes. This means that
   heavy houses with solid construction should
   not rest on hard rock bases, but instead on

bad good ideal

dangerous safe

15. 3

15. 2

15. 5

15. 6