BUILDING MATERIALS

When choosing materials for a building in high-risk earthquake zones, there are two ways to deal with seismic waves:  1) build the structure rigid enough that it is able to resist disintegration because of its cohesion and solidity, or 2) build the structure flexible enough so that it will bend rather than break.  Different building materials thus respond to earthquakes in different ways (Tazieff, 1989).

 

  

UNREINFORCED MASONRY

Buildings built of unreinforced masonry are among the most susceptible to earthquake damage because 1) the floors and roof are often weakly attached to the walls, causing the walls to fall outward while the earth shakes; and 2) the walls are normally not strong enough to absorb the force created by the shaking—it is easily pulled apart.  However, even though unreinforced masonry is the worst choice for building material, it is also the cheapest.  Thus, lower income groups and periphery countries often experience more destruction and deaths than higher income groups and core countries (U.S. Congress,1995).

 

  

CONCRETE AND REINFORCED MASONRY

Buildings with reinforced masonry, concrete frames, or precast concrete are generally less dangerous than unreinforced masonry; however, they are still not the most desirable building materials.  The frame of the building can fail during an earthquake even if the walls have absorbed the force of the shaking earth; concrete panels can collapse during an earthquake because of insufficient connections between walls, roof and floors (U.S. Congress,1995).

 

  

WOOD

Wood is the favored material for smaller buildings such as single-family homes.  The wood is flexible and will bend without breaking or failing.  A wood frame will rarely collapse in an earthquake, however, if the house is on unsecured concrete foundations, the building may fall off the foundation (U.S. Congress,1995).

 

  

STEEL

Steel frames are generally the ideal building material for taller structures because of its strength, durability, flexibility and ductility; steel buildings are unlikely to fail during an earthquake.  However, the Northridge earthquake of 1994 proved steel buildings to be vulnerable to the ground shaking as well.  More than 100 steel-framed buildings were cracked from the earthquake near the confluences of the steel frames and the steel columns (U.S. Congress,1995).