Engineering and Construction

The purpose of this section is to present examples of structural damage caused by earthquakes. A lot of
this damage is related to foundation conditions.

1 Torsion   Torsional problems develop when the center of mass of the structure is not located at the center of its lateral resistance, which is also known as the center of rigidity. A common example is a tall building that has a first floor area consisting of a space that is open and supports the upper floors by the use of isolated columns, while the remainder of the first floor area contains solid load-bearing walls that are interconnected.

The open area having isolated columns will typically have much less lateral resistance than that part of the floor containing the interconnected load-bearing walls. While the center of mass of the building may be located at the mid-point of the first floor area, the center of rigidity is offset toward the area containing the interconnected load-bearing walls. During the earthquake, the center of mass will twist about the center of rigidity, causing torsional forces to be induced into the building frame.

2 Soft Story   A soft story, also known as a weak story, is defined as a story in a building that has substantially less resistance, or stiffness, than the stories above or below it. In essence, a...

3 Pancaking   Pancaking occurs when the earthquake shaking causes a soft story to collapse, leading to total failure of the overlying floors. These floors crush and compress together such that...

4 Shear Walls   There are many different types of structural systems that can be used to resist the inertia forces in a building that are induced by the earthquake ground motion. For...

5 Wood-Frame Structures   It is generally recognized that single-family wood frame structures that include shear walls in their construction are very resistant to collapse from earthquake shaking. This...

6 Pounding Damage  Pounding damage can occur when two buildings are constructed close to each other and as they rock back-and-forth during the earthquake, they collide into each other...

7 Tsunami and Seiche   Tsunami is a Japanese word that when translated into English means harbor wave and it is defined as an ocean wave that is created by a disturbance that vertically displaces...