Three factors drive our research: (1) relevance, (2) interest, and (3) training of students. While pursuing research, we aspire for a confluence of technical knowhow, stakeholders (e.g., users, policymakers), and a production line. Highlights of research work from our group are briefly presented below.

3D concrete printing

Work on 3D concrete printing started as a PhD student showed interest. In the initial years, methods to print concrete with a rather low initial yield strength (e.g., 30 Pa), and for horizontal spanning of printed concrete layers were developed. During this time the student co-founded micob.

Our next pursuit was driven by the needs of the Indian Army, namely, development of thousands of bunkers along international borders. Subsequently, we developed India's first 3D printed bunker for the Army that was tested under rounds of rocket launchers, T90 tank and other weapons. The bunker could be constructed very fast, and its cost was similar to equivalent conventional bunkers. The Southern Command of the Indian Army presented a commendation card to appreciate the work. Thereafter, the Indian Army announced adoption of these bunkers, and other 3D printed concrete structures. Hundreds of the bunker's variants have been deployed in the forward areas, including at high altitude. These bunkers were supplied on a commercial basis by micob.

A key limitation of the concrete being printed today across the world is lack of reinforcement in the printed layers, which makes it vulnerable to brittle failure. Our group has been working to develop methods to introduce intra-layer and cross-layer fiber mesh reinforcements in the printed concrete layers in a systematic and automated manner.

Seismic isolation

We started working towards the seismic isolation of the under-commissioning prototype fast breeder reactor in collaboration with Indira Gandhi Center for Atomic Research (IGCAR). The structural system of the reactor comprises a rather complex arrangement of fluid-shell system. We developed closed-form solutions to understand the dynamic behavior of different components. We further developed a simplified model of the reactor and examined the influence of seismic isolation on the reactor. Seismic isolation reduced the floor accelerations by an order of magnitude (e.g., by 10 times). Further analysis suggested that the reactor that is designed for the seismic hazard at Kalpakkam could possibly be deployed in regions with much greater seismicity, if suitable seismic isolation systems are utilized.

The above study considered sliding bearings for seismic isolation. Noting that India imports sliding bearings for almost all projects, we started working to develop a sliding isolation device in collaboration with IIT Kanpur. Harsha Engineers International Ltd. has been our industry partner. A series of tests suggest that the device is functioning as intended. Additional work is ongoing to further enhance the device. It is hoped that these devices will be commercially available one day.

Efforts noted above can be seen in the context of India's quest for net zero carbon emission through large-scale deployment of nuclear energy. National Thermal Power Corporation (NTPC) is expected to spearhead this exercise. It is increasingly being recognized that one or the other form of seismic isolation will be essential if a particular reactor is to be deployed across regions with varying seismic hazard.

A workshop on seismic isolation was organized at IIT Gandhinagar, which allowed exchange of ideas among stakeholders including national and international experts, nuclear industry (NTPC, IGCAR, BARC, NPCIL), and a potential manufacturer of isolation devices.

Resilience of power transmission networks

Cyclone Fani, which hit the coast of Odisha, caused collapse of and severe damage in 100+ high voltage power transmission towers. We then decided to study the lattice towers at the system as well as individual level.

The system's perspective involved explicit consideration of each of the 40,000+ towers in Odisha, realistic cyclone scenarios, and a representative structural fragility curve developed based on damage data collected from Odisha Power Transmission Corporation Limited (OPTCL) through a series of RTI applications. Relevant wind speed models and data were used to determine wind speeds at the locations of the towers. The study allowed insights on prioritizing the transmission towers in a region for strengthening, and cost-effective strengthening approaches. For example, strengthening around 3,000 towers in intuitively selected geographical clusters by "20%" could be a cost-effective strategy in long run.

The system's work got considerable media coverage: The Hindu BusinessLine, Indian Express, Economic Times, Telegraph, OdishaTV, Divya Bhaskar.

The individual tower's perspective involved wind tunnel tests and computational fluid dynamics-based analysis of a delta segment, which is frequently damaged in India, as noted in the reports of Central Electricity Authority (CEA). The aerodynamic forces were found considerably greater than what one would calculate using design standards.

Subsequently, we conducted a workshop on resilience of power transmission infrastructure that had representatives from OPTCL, CEA, IIT Roorkee, IIT Bombay, NPCIL, TCPL, SERC, and GUVNL among others. The discussions helped us identify problems to work on.