What You Should Know Before Buying an Earthquake-Resistant Home

In light of the devastating earthquakes in Japan, Indian Ocean, and most recently, Nepal, the question that comes to mind is how safe are our homes during an earthquake? Even aftershocks with enormous magnitudes are capable of significant damage to life and property. Engineering advances have ensured that your home can be built to resist modest to severe quakes.

While earthquakes themselves cause extensive destruction, buildings, bridges, and other structures tend to collapse and further the damage. Engineering techniques developed for earthquake-resistance structures minimize considerable sideways motion, allowing you to safely exit these buildings.

Properties of an Earthquake-Resistant Home

• The general consensus is that an earthquake-proof structure or building should be heavy to withstand the impact of any seismic activity. However, this is further from the truth. A lightweight building absorbs more impact than a traditional concrete one.
• The number one feature of such homes and apartments is a technique called “base isolation”. These buildings do not directly sit on the ground, and are protected from shocks. They may, at the most, sway in the event of a major earthquake.
• “Tuned mass dampers” can be used to dampen the swaying of buildings. These dampers are large devices that sway at the top of buildings, as opposed to the entire structure. A notable example of such a damper is the 660-tonne steel pendulum in the Taipei 101 building, suspended from the 92nd to the 87th floor, which counters movements caused by quakes and strong winds.
• Properly constructed in-fill walls strengthen the overall structure of the building. A strong core-shear wall will provide the necessary stiffness to reduce swaying. Friction dampers and yielding dampers also contribute to minimal damage during earthquakes.
• Materials of high ductility, where materials are subjected to large processes of plastic malformations, greatly reduce impact. The Burj Khalifa consists of such a design where a tubular system with structural steel absorbs a large amount of impact energy, and serves to minimize significant damage.
• Another factor to be considered is the soil on which the building stands. During earthquakes, sandy and clayey soils undergo liquefaction and surge to the surface causing damage.

Things to Remember While Buying or Renting a New House

• Always inquire and assess the building before renting or purchasing to avoid any major setbacks later. Take the help of a structural engineer and make an informed decision about your purchase. If you find any shortcomings, get the building retrofitted.
• The basic strategies to building a stable home are that,
• The soil must be stronger than the foundations
• The foundations must be stronger than the columns and
• The columns must be stronger than the beams

A few key points to remember:

1. Be aware of the seismic activity of the building site.

2. Determine if the building has excessive architectural features, such as cantilevered staircases, that are prone to seismic disasters.

3. Ensure the building has a simple circular or rectangular geometrical plan. Avoid or be wary of buildings that are H-, L-, U-, V-, and Y- shaped.

4. Check the stability of the staircase, if available, as it will be the only escape route during an earthquake. It should be designed to resist collapse.

5. Floating columns, which do not run into the ground, are an additional risk.

6. Stilt parking, commonly seen in apartments, require a ductile design for its columns.

The demand for earthquake-resistant homes is fairly new in India. While these techniques have been implemented in countries like Japan and United States, it will be some time till it gains a wider foothold in India. 

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