  Poor construction in Haiti was a major reason so many people died when a 7.0 magnitude earthquake struck the impoverished nation in January. (photo: Reuters) |
Attaching shutters to windows or embedding steel bars in new structures are some of the simple measures that should be employed to stop buildings from killing occupants in natural disasters, experts say.
Poor construction in Haiti was a major reason so many people – up to 300,000, according to the president – died when a 7.0 magnitude earthquake struck the impoverished nation in January, architects and disaster specialists say.
And in quake-prone Chile, where an earthquake and a subsequent tsunami killed about 500 people in February, the government is investigating to what extent rules on fortifying buildings against seismic shocks were followed.
“You don’t need to be helpless. You can build safer, you can build better to reduce both the financial cost but of course also the life [cost],” says Margareta Wahlstrom, U.N. Special Representative of the Secretary-General for Disaster Risk Reduction.
“It’s not the earthquake that kills people, it’s the buildings that collapse in the earthquake.”
While some countries put great emphasis on erecting buildings that can survive tropical storms, floods or earthquakes, many others lag far behind, she says.
Safe construction is not part of international development policies either, Wahlstrom says, adding that she hopes it will now be included after Haiti and Chile.
A step in that direction is a new handbook for rebuilding after natural disasters released by the World Bank last week.
Intelligent design
Safer buildings alone will not always prevent deaths. Houses should be located away from hazardous areas, where possible, and combined with an early-warning system, evacuation plans and public education on what to do when a disaster strikes.
But as part of an overall strategy to minimize deaths and destruction, intelligent building design is one of the most straightforward solutions.
For example, shutters on windows will prevent wind from blowing through the building and lifting it off the ground. Tying the roof to the walls will stop it from being blown off.
To protect new buildings against earthquakes, walls can be reinforced with crisscrossing diagonal steel beams or concrete columns. Such – often life-saving – features add less than 10% on average to building costs, experts say.
Designs should take account of what resources are affordable and available locally. For example, in areas where water is short, building concrete houses is not viable, as making concrete requires a lot of water.
Easier drawn than done
While there is no shortage of clever ideas, implementation can be complicated, especially in developing countries.
For a start, most people in poor nations live in houses that they have built themselves, mostly without an understanding of structural engineering or knowledge of ways to make them safer.
Rolling out a nationwide campaign for safer construction of homes may have the greatest impact in the long term, experts from engineering firm Arup say.
However, organizations involved in post-disaster reconstruction can help by building houses that can be easily replicated by local people. Those willing to build their own homes can be trained how to build with disasters in mind.
Training in how to build safely is one of the services that a new consulting centre in Haiti’s capital will provide.
Architecture for Humanity, a non-profit design and building group, is planning to open the centre in April for three years.
BUILDING SAFER BUILDINGS
Here are examples of simple and more advanced techniques to make buildings safer in natural calamities:
Earthquakes
To withstand earthquakes, buildings have to be sturdy. To achieve that:
- The most stable buildings are symmetrical, for example, square rather than L-shaped.
- The materials used should be flexible so they bend rather than break under impact. For example, stonework or brickwork is not flexible, while timber and masonry reinforced with steel are.
- When inserting doors or windows into a wall, leaving equal spaces between them will ensure the wall is stronger as no section of it is too narrow.
- Horizontal beams, known as “ring-beams,” should be provided at ground and roof level to tie the building together.
- Brickwork panels can be either tied to concrete columns or reinforced with steel bars.
- Buildings can be built around a steel frame.
- Walls can be reinforced with crisscrossing diagonal steel beams.
- Traditional houses made of stone, mud or timber can be reinforced by attaching steel-and-concrete bars outside and inside their walls and connecting them.
- Traditional mud-plastered roofs can be improved by inserting a sheet of plastic between the layers of mud to stop leaks. That way the roof won’t require repeated re-plastering that makes it heavy and dangerous in the event of an earthquake.
Floods
- When building a cyclone shelter, engineers in India advise putting the foundation deep in the ground to avoid erosion from prolonged exposure to water and making the corners curved to reduce the impact of strong wind and water.
- Houses can be built on stilts or on higher ground
- A novel idea is a “floating house,” which a group of architects built last year for actor Brad Pitt’s Make It Right foundation in New Orleans. The house is designed to rise off the ground on steel masts as flood waters pour in.
Tropical cyclones/typhoons/hurricanes
- Shutters on windows will prevent wind from blowing through the building and lifting it off the ground.
- Tying the roof to the walls will stop it from being blown off.
- Building a roof with a gentle slope will reduce the impact of the wind on it and help drain the water off the roof to prevent leaks into the interior.
