#7: Leadenhall Building – London (2015)
The Leadenhall Building, widely known as the “Cheesegrater,” opened as one of London’s technically distinctive skyscrapers, but problems with some of its structural bolts emerged soon afterward. Several large bolts used in the building’s unusual external structural system fractured, prompting an extensive investigation into whether the failures represented isolated defects or a broader risk. Engineers determined that hydrogen embrittlement had affected certain high-strength bolts, making them vulnerable to cracking despite appearing suitable when originally installed. Protective measures were introduced while the affected components were identified, and a large-scale replacement program was undertaken rather than waiting for additional failures to reveal themselves. Thousands of bolts were inspected, with a substantial number ultimately replaced as part of the corrective work beginning in 2015 and continuing afterward. Because the Leadenhall Building deliberately exposes much of its structural engineering as part of its architecture, the problem attracted particular attention within the construction industry.
