Sarwidi designs earthquake-resistant buildings

Sarwidi designs earthquake-resistant buildings

Sri Wahyuni, The Jakarta Post/Yogyakarta

In the wake of the apocalyptic tsunami that hit major parts of Aceh and North Sumatra, people living in earthquake-prone areas throughout the country must be wondering about the desirability of earthquake-resistant homes.

Most parts of Indonesia are earthquake-prone.

However, poor anticipation and limited scientific efforts to predict the arrival of earthquakes means that natural disasters become fatal, especially large magnitude quakes.

"The quake itself is not lethal, but the ruins of a building ripped off by the quake can kill people," said Sarwidi, who holds a doctorate in civil engineering from the Yogyakarta-based Indonesian Islamic University (UII), and who underlined the urgency for people living in areas prone to earthquake to have earthquake-resistant houses.

Encouraging people to construct buildings resistant to earthquakes, according to Sarwidi, is not difficult, as science and technology have made it possible to determine the zones as well as the intensity of potential earthquakes around the globe.

"By encouraging people to build only earthquake-resistant buildings in areas considered prone to earthquakes, we can prevent such natural phenomenons from turning to disasters," said Sarwidi, who is also director of the UII Center for Earthquake Engineering, Dynamic Effects and Disaster Studies (CEEDEDS).

"Earthquakes may occur, but we can prevent them from destroying our houses by making them resistant to earthquakes," he added.

Earthquake-resistant houses are relatively affordable. Additional cost is only needed to make a more "elastic" or ductile building.

"The keys to an earthquake-resistant building are 'not too heavy or brittle'," he said.

CEEDEDS has conducted a series of observations in several regions in the country that have been hard-hit by earthquakes, and the studies have proved that the majority of damaged buildings have not been appropriately constructed.

They are buildings that are traditionally designed, built by local workers, using locally available materials, and are not constructed under the supervision of a professional. They are the kind of buildings that most Indonesian families occupy, even in urban areas.

"Therefore it is urgent that information be disseminated to improve people's knowledge about the concept or theory of a building's resistance to earthquakes," he said.

For this purpose, CEEDEDS has issued a manual on how to build simple, earthquake-resistant buildings, titled Manual Bangunan Tahan Gempa untuk Rumah Tinggal Sederhana Tembokan (Earthquake- resistant Building Manual for Simple Concrete Homes), that anyone, especially mandor (traditional construction supervisors) can use as a reference.

In many traditional buildings a mixture of bricks and cement is used, instead of a concrete construction with reinforcing steel structure inside as the foundation band that renders them resistant to sway or quake.

The manual also suggests ensuing that walls, usually made of either clay bricks or batako (concrete blocks), are made in the right way by adding enough vertical and horizontal concrete frames.

"Ideally, every three square meters of wall should be framed with vertical and horizontal concrete supports. Reinforcing steel bars, eight millimeters or 10 millimeters in diameter, are sufficient for this purpose," Sarwidi explained.

No less important when constructing a house that purports to be resistant to earthquake, according to the manual, is the existence of a roof band.

Such construction in principle unites the structure of the entire building, making a house more resistant to sway and quake.

Evidence supporting the CEEDEDS concept relates to an earthquake that jolted the Central Java town of Banjarnegara: a house on a riverbank was left intact while other houses in the vicinity were shattered. The house was designed using CEEDEDS concepts.

"I have made instruments, which I call Alat Goncang Gempa (earthquake simulator), to prove that a house with such a structure is resistant to earthquakes," Sarwidi said.

It is necessary to confirm the concept because Suwardi strongly believes that many traditional houses are built without considering safety and strength, which includes concrete foundation bands, concrete frames for wall reinforcement and concrete bands for the roof.

"My research has revealed that a house built using these concepts can resist 11 consecutive quakes," he said.

Therefore, it is urgent that these building concepts be disseminated to as many people as possible, especially those living in areas prone to earthquake.

CEEDEDS has promoted the ideas to mandor in several earthquake-prone regions.

"We welcome anyone who would like to know more about our innovations for earthquake-resistant buildings," Sarwidi said.