Earthquake Resistance Design – Introduction

by ce on March 11, 2012

Earthquake is a natual disaster in the form of ground shaking caused by the sudden release of energy in the Earth’s crust. This energy release is usually originated from dislocations of the crust and volcanic eruptions. The other sources of energy release that produce earthquake-like event are man-made explosions and collapse of underground tunnel. The ground motion resulted from an earthquake produces large-magnitude forces of short duration on any buildings and infrastructures on the Earth’s surface near the source of the earthquake.

These large forces generated from earthquake may collapse or damage buildings and other infrastructures and may cause a lot of loss of lifes. Thus earthquake has been recognized as a major problem for mankind. To minimize the impact from earthquake, buildings and other infrastructures such as bridges, dams, etc. must be properly designed to resist the earthquake forces. Before we go into details on how to design structures to resist earthquake forces, it is wise to understand the way the earthquake forces induced onto the structures. Unlike other types of forces in which they are externally applied to structures, the earthquake forces are basically inertia forces.  It means that the earthquake forces are generated due to the mass movement of buildings or infrastructures initiated by their base movement as shown in Figure below. Since the earthquake force is inertial force, its magnitude is a function of mass of the structure.

Building under Earthquake

In analyzing a structure against earthquake loads, we may consider the earthquake forces consisting of horizontal components along two perpendicular directions and a vertical component.

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