Is the CONCRETE FRAME HOUSE MOST SECURE for EARTHQUAKE RESISTANT HOUSE (2)

In the midst of my routine busyness (and bored to!) to wrote my PhD thesis, I tried again to fill this blog just in order not to neglect and fills my saturated time since being away from my wife and kids this (... ehem). My topic now is not far away from the theme of my thesis, traditional Javanese house and its relation to earthquakes.

STIFFNESS, STRENGTH, and DUCTILITY

As a result of the earthquake in Bantul 2006, many buildings whether it is called traditional or modern building, mostly badly hit by the devastated earthquake. Soon after, the government and hundreds of donors rebuilt shelters in the Bantul and surrounding areas with new houses through a reconstruction program. The popular reconstruction house types were built from bricks wall altogether with reinforced concrete frame. Those new houses are considered the safest or most appropriate to anticipate the future earthquake. Previous homes, especially the traditional houses, are considered less suitable for earthquake resistant buildings. So the people in Bantul and surrounding communities then build their homes with this type of reinforced concrete which was previously not widely used, especially by rural communities who had still familiar with the house bricks or wooden house using 'gedhek' or 'gebyok'. Now it can be ascertained when you come to the Bantul, old style house ‘tempo doeloe’ such as Javanese Limasan, is rarely used anymore in Bantul, and just as a memory.

Just to note, that houses by framework of concrete bricks indeed be one solution to the earthquake-safe building houses but not the safest one. The nature of the framework of concrete brick wall relies on the principle of stiffness and strength rather than ductile. The principles of earthquake resistant buildings are supposed to cover all three issues. Stiffness is the principle of building to resilience the shocks so that the building does not change in shape, while building strength is the principle of maximum load of an earthquake can be accommodated, so it is always associated with load resistance. Ductile in the other hand more to do with building endurance to change its shape (flexible, plastic), or absorb the force, according to the existing burden. The principle stiffness in buildings is by applying heavy materials such as bricks and concrete that is rigid or rigid and not flexible. While ductile is more suitable when using a material like wood and steel.

Unfortunately, the principle of prioritizing the stiffness first in building only fit for the area that have small earthquake risk since consideration to resist shocks will be relatively low. This is worst by the burden of building by using materials such as bricks and concrete slabs. High load in addition to relatively low plasticity are also vulnerable to the dangers of rolling for lateral or horizontal forces caused by the earthquake. It's also very dangerous if used as a residential building since it element will ruins the occupants under yet of lightweight materials such as wood. Furthermore, if the quality of implementation is also low, the risk of earthquake will be very-very high.

This is what bothered over my mind. New houses in Bantul were completely been built using bricks and concrete slabs. Regardless of whether its implementation is right or not, the use of this material type is still worrying for earthquake prone areas such as in Bantul. The houses with a high ductile principle should be more secure and less stressed rather than the reinforced concrete which is more rigid and brittle. Although some opinions said it would be very expensive for using wood, but the reinforced concrete building materials are also not that expensive now? And probably should not be forgotten, the potential use of local wood or bamboo or palm-coconut wood also still can be improved. And another thing, by building houses made of wood we will also return to preserve the Javanese traditional house which previously been widely used (in the future we will discuss why many traditional houses collapsed in the quake of 2006 in Java).