29-06-2012, 12:25 PM
EARTHQUAKE RESISTANT STRUCTURES
EARTHQUAKE RESISTANT STRUCTURES.pptx (Size: 1.16 MB / Downloads: 99)
What is an Earthquake?
An earthquake is a sudden, rapid shaking of the Earth caused by the breaking and shifting of rock beneath the Earth’s surface. Man has been terrified of this phenomena for ages, as little has been known about the causes of earthquakes, but it leaves behind a trail of destruction.
Earthquakes occur when tectonic plates move and rub against each other. Sometimes, due to this movement, they snap and rebound to their original position. This might cause a large earthquakes as the tectonic plates try to settle down. This is known as the Elastic Rebound Theory.
Natural Calamities
Natural calamities are the phenomenon which can’t be prevented, but we can take precautions to minimize their effects. Calamities such as Floods, Cyclones, Volcanic eruptions, Tsunamis and Earthquakes can cause a lot of damage to life and property, and cause disturbance to our day-to-day life.
Building Stiffness and Flexibility
The taller a building, the longer its natural period tends to be. But the height of a building is also related to another important structural characteristic: the building flexibility. Taller buildings tend to be more flexible than short buildings. (Only consider a thin metal rod. If it is very short, it is difficulty to bend it in your hand. If the rod is somewhat longer, and of the same diameter, it becomes much easier to bend.
How Earthquakes affect Reinforced Concrete Buildings
A typical RC building is made of horizontal members (beams and slabs) and vertical members (columns and walls), and supported by foundations that rest on ground. The system comprising of RC frame. The RC frame participates in resting the earthquake forces. Earthquake shaking generates inertia forces in the building, which are proportional to the building mass.