Researchers develop low-cost braces to improve earthquake resistance of buildings and bridges

Tribune News Service

Vijay Mohan

Chandigarh, May 19

Researchers have developed a low-cost device that will improve the resistance of buildings to earthquakes. Called buckling-restrained braces, these have several advantages such as all-steel components, on site fabrication and assembling, post-earthquake inspection and easy replacement.

The development assumes significance as large parts of the country are vulnerable to earthquakes and seismic activity.

According to the Ministry of Earth Sciences, about 60 percent of the Indian landmass is prone to earthquakes of different intensities, with 11 per cent and 18 per cent of the area falling into the top two riskiest zones. India has experienced a number of devastating earthquakes in the past.

The earthquake resistance of buildings and other structures can be improved by using seismic force-resisting systems or vibration control devices. Buckling-restrained braces are the special structural elements that serve both purposes.

Researchers at the Indian Institute of Technology, New Delhi, have fabricated unique hybrid braces that have high strength ductility and energy dissipation potential, the Ministry of Science and Technology said in a statement issued today.

Prof Dipti Ranjan Sahoo and Dr Ahmad Fayeq Ghowsi studied the seismic performance of over 10 full-scale hybrid braces. Tests are being conducted on specimens with improvements and modifications and a patent has been applied for the bracing system.

A hybrid system comprises two parts – a non-replaceable elastic steel brace and a replaceable buckling-restrained brace connected lengthwise. The core elements are designed to undergo inelastic deformation under stress to provide the required strength, ductility and energy dissipation during earthquake induced vibration.

“These braces can be customized depending on the seismic demand expected on buildings or bridges located in different seismic zones of India,” Prof Sahoo said in a statement. “The proposed technology is effective in new constructions and has a great potential for the upgradation and retrofitting of seismically deficient reinforced concrete and steel framed structures, such as residential or office buildings, hospitals and schools,” he added. These braces can also be used in steel and concrete bridges to enhance their earthquake resistance.

“The implementation of this technique in existing structures reduces overall retrofitting cost and minimizes the intervention and downtime. It is possible to design a structure to achieve the required performance objectives in terms of strength and serviceability utilising the hybrid buckling-restrained braces,” the ministry’s statement said.