Henry Fountain from the New York Times looks at Haiti’s infrastructure past to explain the devastation:
Engineers and architects who have worked in or visited Haiti say that substandard design, inadequate materials and shoddy construction practices likely contributed to the collapse of many buildings in the earthquake that struck Tuesday.
Cameron Sinclair, executive director of Architecture for Humanity, a nonprofit design group based in San Francisco, said he was “horrified” when he visited Port-au-Prince and Gonaïves last October to assess the quality of construction there.
Mr. Sinclair said that design and construction were far worse than in other developing countries he had visited. “In Haiti, most if not all of the buildings have major engineering flaws,” he said.
The New York Times also discusses the quality of concrete:
Most houses and other structures are built of poured concrete or block, there being very little lumber available due to mass deforestation, said Alan Dooley, a Nashville architect who designed a medical clinic, built of reinforced concrete, in Petite Rivière de Nippes, a fishing village 50 miles west of Port-au-Prince.
Concrete is very expensive — much of the cement for it comes from the United States, Mr. Dooley said — so some contractors cut corners by adding more sand to the mix. The result is a structurally weaker material that deteriorates rapidly, he said. Steel reinforcing bar is also expensive, he said, so there is a tendency to use less of it with the concrete.
The BBC looks at why so many more people died in Haiti than in Chile. Currently only 700 are reported dead compared to 220,000 in Haiti–despite the fact that the Chile quake was 500 times stronger. The article reviews what is called the ‘strong columns weak beams’ system for keeping buildings upright:
The idea is that buildings are held up by reinforced concrete columns, which are strengthened by a steel frame.
Reinforced concrete beams are joined onto the columns to make floors and the roof.
If there is an earthquake, the idea is that the concrete on the beams should break near the end, which dissipates a lot of the energy of the earthquake, but that the steel reinforcement should survive and the columns should stay standing, which means the building will stay upright.
The problem is that an 8.8 magnitude earthquake is “towards the top end of what you’re designing for”, according to Professor Colin Taylor, professor of earthquake engineering at Bristol University.
Another advantage for the Chilean quake was that its epicentre was 21 miles (34km) underground, off-shore and 70 miles (115km) from the nearest big city, Concepcion.
The energy from earthquakes falls the further away you are from the centre.
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