Corroded nuts, bolts likely caused steel in statue to fail, ‘ankle’ critical for stability: Expert

New Delhi/Mumbai: Corroded nuts and bolts likely contributed to the collapse of the Shivaji statue by causing a failure in steel members forming the frame inside the statue, according to a structural engineer.

‘Ankles’ of a statue, where the weight of the entire structure comes to rest upon, are most critical for stability and hence, require special attention during the design stage, said Amresh Kumar, a structural engineer with a consultancy.

On Monday afternoon, the 35-foot statue of Chhatrapati Shivaji Maharaj, the Maratha warrior king, collapsed. The statue, built by the Indian Navy, was unveiled by Prime Minister Narendra Modi at the Rajkot fort in Maharashtra’s coastal Sindhudurg district about eight months back.

While officials have claimed that winds blowing at speeds of 45 kilometres an hour caused the collapse, wind speeds up to almost three times these are accounted for while designing a structure, according to the Bureau of Indian Standards.

“In this statue’s case, external factors such as loads or climatic conditions do not appear to have caused trouble. Rather, corrosion in the nuts and bolts, as mentioned in the PWD report, could have caused a failure of steel members making up the frame inside the statue,” Kumar told PTI.

On August 20, an assistant engineer at the Maharashtra Public Works Department (PWD) had written to Naval commander Abhishek Karbhari, Area Coastal Security Officer and Area Civil-Military Liaison Officer, pointing out that the nuts and bolts used in fixing the statue on the fort were catching rust because of exposure to ocean winds and rains.

“While steel members forming a structure – in this case, the statue’s frame – are commonly protected against corrosion, the nuts and bolts used in connecting these members are commonly ignored, leaving them more vulnerable due to exposure to environment,” Kumar said.

He recommended that along with members, nuts and bolts also be protected, either by painting or galvanising, especially in coastal regions where the air is rich in moisture and salt, and is therefore, more corrosive. Galvanisation refers to applying a protective layer of zinc on steel or iron, usually by dipping them in molten zinc.

However, despite the highly corrosive environment, the corroding of nuts and bolts, thereby causing a collapse in about eight months following construction should not have happened, according to the engineer.

Bolts employed in connecting the steel members and providing stability can often be procured at a construction site much before they are due for installation, Kumar said.

He suggested that therefore, regular checks at the site, especially before installing them or using them in construction, are required.

The toppling of the Shivaji statue bears a striking resemblance to that of a 40-foot-tall statue near Birsa Munda Hockey Stadium and Rourkela Airport in Odisha, which happened in June last year – both the statues gave way near the ‘ankle’ region of the people they were depicting.

The ‘ankles’ of a statue – where the weight of the entire structure comes to rest upon – end up being the most critical to its stability, Kumar said.

“Statues are, in essence, tall and slender structures supported on a compacted base, in which anchor bolts are closely or densely packed. Special attention, therefore, needs to be given to ‘ankles’ during the design stage, such that the statue's centre of gravity is maintained and does not cause tensions at the base,” he explained.

He added that in regular structures, like buildings, beams and columns are arranged in a ‘grid’ manner such that if a column fails, the surrounding members act as “back-up” to preserve structural integrity.

“On the other hand, statues are usually ‘vertical cantilevers’ in that they are supported at one end (at the base) and free at the other. The framing members and connecting bolts at the base are the sole bearers of the weight acting at the point and, therefore, there are no ‘back-up’ members in an event of failure,” Kumar said.

The statue in Odisha had been installed in January last year, ahead of the FIH Odisha Hockey Men’s World Cup 2023, and was dedicated to hockey players.

Meanwhile, Chetan Patil, the structural engineer named in the offence registered in connection with the Shivaji Maharaj statue collapse, has claimed that he was not the structural consultant for the statue.

“I am nowhere related to this. I did not have any work order that I was appointed to. The work was given to the Thane-based firm. I was just told to work on the platform on which the statue was being erected,” he said.

Speaking to the Marathi channel ABP Majha over the phone, Patil, named in the FIR along with the artist Jaideep Apte, said that he had submitted the design of the platform to the Indian Navy through the Public Works Department (PWD) and had nothing to do with the statue.

“It was a company in Thane which had done the statue-related work,” Patil is heard saying while speaking to the channel. Asked why he was named in the FIR, Patil said his name was drawn into it.