A second test of a wood frame structure with metal roof also passed the 10.0 earthquake simulation but scientists credited a layer of rubber tires underlying the foundation as the reason. “It wasn’t the wall material at all,” says test sponsor and home designer Dr. Alan Early. “It was the foundation. We used recycled tires as shock absorbers under the slab.”
These concrete houses have a footprint of 270 square feet and are designed for a family of six. Both the concrete and wood houses have unique green building features for environmental friendliness. The house bases have 40% of steel rebar replaced by bamboo of the same diameter. Bamboo is both lighter and stronger than traditional materials and its cultivation is environmentally friendly. Both houses are erected on a layer of discarded automobile tires as a very low-cost and successful shock absorber/damper mechanism.
IAF has developed an improved construction method for rapidly building mass quantities of earthquake-proof housing. The concept is to build houses on a factory assembly line. This speeds up the process from the typical 3 to 4 weeks to build a house to the ability to build 20 houses in a single day.
The houses are built using specialized steel forms that can both set up and then release from the concrete quickly. Furthermore, the rebar reinforced “early strong” cement sets up rapidly. Several concrete additives, including fly ash, petrochemical byproducts and super plasticizers, all of which are readily available in Indonesia, increase concrete strength. The total capital cost to set up a factory is USD $100,000.
The design of the house features a steep roof with wide overhangs that is practical for heavy winds and rain and matches the typical Indonesian style of house. The homes are designed for a family of six making $100 a month. Most families with lesser income already live in very safe bamboo houses. Extensive coordination and consultation with the Research Institute for Human Settlements of the Indonesian Ministry of Public Works have ensured this design conforms to Indonesian cultural tastes and preferences. Individual families qualifying for government loans will provide proof of land ownership and work on their own home. The houses will cost only $995.00.
Unfortunately, suffering from homelessness or living in inferior housing is not unusual in Indonesia. The tsunami disaster in 2004 destroyed 21,659 homes and the Mount Merapi earthquake in 2005 flattened another 4,000 homes. Of the 5,800 lives lost in the earthquake, many were crushed in their poorly built houses or were hit by heavy roof tiles that shook loose. Because of a housing backlog, the current demand for safe and affordable housing can easily top four million homes, says Early.
The IAF anticipates that Early’s design will ultimately be an important part of the solution to the significant housing shortage in Indonesia. An earthquake greater than 10.0 on the Richter scale is only likely to occur every 1500 years. For a structure to withstand such forces is unprecedented in known shake tests and actual earthquakes. The concrete home withstood not just one test, but the accumulated effect of 10 earthquakes ranging from one to over 10 on the Richter scale. “To pass these vigorous tests with only minor hairline cracks is unheard of and to our knowledge hasn't been successfully done anywhere else in the world,” says Early. “We are ecstatic about the results and are looking forward to making this safe home design available to the people of Indonesia!”
Issued: May 10, 2007
Page: pp.42-43
Copyright: 2007 R.W. Nielsen Company