The Leadenhall Building at 122 Leadenhall Street in London, also known affectionately as the Cheesegrater due to its unique shape, is 47-stories tall and is the UK’s 4th largest building. Featuring a cutting edge high-performance building envelope incorporating passive heating and cooling elements, 85% of its construction took place off-site, making it one of the largest and most complex prefabricated projects to date.
Unfortunately, in early November, a large bolt broke off and fell to the ground, while another bolt broke and fell inside the building. Fortunately nobody was hurt, but the event has caused a great deal of concern. The bolts in question are key structural components and each one is similar in size to a human hand. There are a total of 3,000 of these bolts.
According to BBC News:
British Land said the structure was still open to workers but a full investigation was under way and all remaining bolts were being fully examined.
“There is no risk to the structural integrity of the building,” the company said.
“Public safety is our priority so we have taken a number of precautionary measures.”
Pavlo Inglesis, of the Quality in Construction Blog writes:
The Leadenhall building is an amazing building and engineering achievement but that sounds like a really major failure and it is probably a miracle that there were no casualties on the ground. It sounds more like a material failure rather than an installation failure but of course this is just only an assumption since no more details were published. There are many questions that need to be answered by the supplier/fabricator/manufacturer of these bolts but it shouldn’t be difficult to figure out what happened and why they failed. It sounds funny to even question the structural integrity of the building after the failure of 2 bolts while at the same time it’s easy to start “blame games” in such cases. On the other hand the failure does sound embarrassing and generated some bad publicity. Blaming the contractor, the Developer or the fabricator will not help the investigation. The important thing here, is for everyone to make sure that such incidents will not happen again and basically learn some lessons after fully investigating the causes.The big challenge would be to find out that root cause and then probably start checking all of the 2998 remaining bolts of the frame…. Who can be sure after that?
Inglesis reports that British Land, the developer of the project, expects a full report to be published after the first of the year. Currently, the general contractor and structural engineer on the project are inspecting each of the other 2,998 bolts.