Earthquakes are natural phenomena that cause the ground to shake violently, triggering landslides, tsunamis, floods and widespread destruction to lives and properties. Geology is the science which deals with the study of why, how, and where earthquakes occur. On the other hand, earthquake engineering is the filed of study dealing with the characteristics of the earthquake ground motion and its effects on engineered structures.
Aside from rain, snow, wind, and gravity loads, the design of prefabricated metal buildings are also affected by seismic or earthquake loads. Earthquakes can cause serious damage if not total collapse of man-made structures. Applicable building codes are constantly updated as more knowledge is gained about seismic action and its effect on the structural integrity of prefabricated metal buildings.
There are specific areas that are highly seismic or earthquake prone. Prefabricated metal structures located in these regions must be designed to deflect and resist the effects of earthquakes.
From the designer’s point of view, earthquake load differs from other loads in many respects since there are many uncertainties involved with its amplitude, duration, and frequency content. Earthquake ground motion can be vertical, horizontal or a combination of both. Since all prefabricated metal buildings are designed to withstand gravity loads, the lateral loads arising from a horizontal ground motion should be considered to prevent severe damage to the structures.
Sometimes, earthquake ground motions are cyclic and induces the reversal of stresses. Because of this, the axially load members of prefabricated metal buildings will have to be designed to resist both tension and compression while beam cross-sections will have to resist not only positive but also negative bending moments.
One important factor that affects the intensity of the seismic action on prefabricated metal buildings is the type of soil where the structure is located. Some particular ground characteristics magnify seismic shock effects.