A primary reason behind devastation brought about earthquakes is that many buildings, especially in high-seismic zones, are either old or not designed to withstand strong seismic forces.
One of the most effective techniques to protect them is base isolation, which reduces the impact of ground shaking by separating the structure from the moving earth.
Base isolators refer to flexible pads or bearings used to separate a building’s structure from its foundation. These range from rubber bearings, friction bearings, ball bearings and spring systems, which help reduce damage to buildings during earthquakes.
Options limited for now
However, traditional base isolators are highly expensive, making them inaccessible to many, especially in rural and economically weaker regions, where resources for earthquake-resistant construction are limited, explains Mohan SC, Associate Professor, Department of Civil Engineering and Associate Dean-Infrastructure and Planning, BITS Pilani, Hyderabad campus.
This challenge is met best through sustained efforts to make a ‘base isolation technology’ affordable for ordinary people, Mohan told businessline on the occasion of World Science Day. A research team by him at the Advanced Structural Engineering Lab, BITS-Pilani, Hyderabad campus, has developed low-cost base isolation solutions.
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Affordable technolgies
“The research is ongoing, with continuous efforts to refine and develop even more advanced and efficient base isolation designs. The ultimate goal is to make earthquake-resistant construction affordable and accessible, particularly for vulnerable communities where the cost of conventional isolation systems is prohibitive,” Mohan says.
Proposed technologies include a non-reinforced elastomeric isolator that uses locally available rubber material, an easy-to-manufacture solution. There is also a fibre-reinforced elastomeric isolator that integrates low-cost natural fibre sheets instead of expensive synthetic fibres. It reduces costs while ensuring durability. A third proposed technology is un-bonded mesh elastomeric layered isolator that utilises a steel mesh sandwiched between rubber layers, enhancing vertical stiffness and flexibility.
‘Shake table’ tests
Thee isolators were rigorously tested on real-life scaled building models using a ‘shake table,’ an advanced facility that simulates actual earthquake conditions. The shake table replicates real seismic ground motions, allowing researchers to assess how well buildings equipped with these isolators withstand earthquakes. Test results confirmed that these isolators can be effectively used for lightweight houses, significantly enhancing earthquake resilience by reducing structural damage, Mohan said.