Expert Talk On New Ways To Combat Earthquakes  

Only precautions taken on your side can battle the loss incurred due to natural disasters. The Nepal earthquake in April 2015 that measured 7.5 on the Richter scale wreaked havoc in the country, crumpling not just life and property but the economy as well. In India, if your region falls in the high-risk zone which includes, the region of Kashmir, the western and central Himalayas, North or Central Bihar, the Rann of Kutch and even the North East Region- you need to be extra cautious about the project that you decide to buy into.

PropGuide reached out to Dr Shih-Ho Chao, Associate Professor in Structural Engineering, University of Texas at Arlington, for his opinions. Below is an excerpt of the interview.

Sneha Sharon Mammen: Is there a cost-effective way to strengthen buildings that aren't earthquake-proof?

Dr Shih-Ho Chao: There are many way to strengthen non-seismic resistant buildings such as using steel bracing, FRP, dampers, or even isolations. Its cost-effectiveness depends on particular structures.

Sneha Sharon Mammen:While inspecting land before a housing project is being made, what are the necessary procedures that one must undertake to ensure greater safety? 

Dr Shih-Ho Chao: Soil testing can be critical for soil contains certain types of sand and at locations having a high amount of water. These soils could have so-called “soil liquefaction” during a major earthquake which makes the soil become like water due to the ground shaking. As a consequence, it cannot support any structures built above it.  Other things that may need special attention are the available area and geometry of the land. If a building is built with a very non-symmetric shape due to the limitation of the available land, its chances to get damaged by an earthquake significantly increases.

Sneha Sharon Mammen: Opting for high-rises is a common phenomenon in the Indian housing market due to lack of space. How should real estate developers make these safer?

Dr Shih-Ho Chao: Modern design and technologies can effectively protect high-rise buildings from being severely damaged by a major earthquake. However, the design may involve higher level computer simulations to reach a more accurate assessment of behaviour and performance under earthquakes. This has become a common practice in the United States. Design firms in the United States and some other countries are moving towards a higher level of requirement, especially for high-rise buildings. Safety is only the minimum requirement. The design codes are gradually switching to so-called “performance-based design” procedure, which requires some buildings to have higher level of seismic performance such as no damage after frequent smaller earthquakes. Important buildings such as hospitals cannot suffer any damage even after a big earthquake. The performance of a specific building depends on owner's desire. Engineers can use many different ways to achieve these requirements. The developers are likely working with design firms to arrive at desired performance before the design is carried out.  

Sneha Sharon Mammen: As per your study and experience, what are the new ways to combat earthquakes (to minimise the risk)? 

Dr Shih-Ho Chao: There are several new ways such as using high-performance materials which are stronger, tougher, and more resilient. One of the examples is a recently emerged concrete material: ultra-high-performance fiber-reinforced concrete (UHP-FRC). This type of concrete material is five to six times stronger than conventional concrete, and much ductile (by “ductile” it means it can pull or push to a large deformation with failure) and tough. Conventional concrete is very inexpensive but can suffer severe damage or totally fail under an earthquake if the design and construction is not appropriately done. Using UHP-FRC not only can considerably enhance the concrete's seismic performance but also likely to reduce the design and construction errors due to the reduced steel reinforcement.  Other methods such as ductile dampers or isolation are also very reliable.

Sneha Sharon Mammen: Are there any incentives that the government provides to retrofit buildings in the United States?

Dr Shih-Ho Chao: I believe in California several cities provide assistance for owners who want to retrofit their old buildings.  The cost needs for retrofitting is much less than the economic losses if a building collapses or is severely damaged by an earthquake.  

Sneha Sharon Mammen: How can a layman with no expertise in structural engineering ensure that he is being offered an earthquake-proof house?  

Dr Shih-Ho Chao: The best way is to talk to the architecture or engineering firm who has designed the building. They know well if the building was designed to resist any earthquake.

Sneha Sharon Mammen: Indian cities mostly opt for traditional ways of construction. The long teslong-testedomes are slowly giving way to prefab homes. Do they pose any risk especially in areas which are high-risk zones?  

Dr Shih-Ho Chao: No matter what material is used, it has to be properly designed in order to fully develop its properties to resist earthquake force or dissipate earthquake energy. Before 1994, engineers in the United States believed that steel structures were more ductile and earthquake-resistant than reinforced concrete and other types of structures. However, the most damaged buildings in the 1994 California earthquake were the steel structures.  It was not steel's problem but the design problems. A brick home could perform well if it is properly designed and reinforced.