Mid-storey box frame
Its not often you see one of these, a mid-storey box frame inserted within a block of flats.
It's not one of our designs I hasten to add, the thought of removing an entire wall length (two in this instance) whilst the flats above are still occupied isn't something we get excited about and rush out to do believe it or not.
In this case we were called to site by one of our clients taking over this job. The previous developer ran out of money and the new guys wanted to make sure the scheme was structurally sound before moving ahead with it.
The problem with box frames is always the bottom beam detailing and temporary works needed to install the whole thing. The top beam is easy enough, needles pushed up as high as they will go and the new beam installed just below it. The bottom beam though....that's within the floor??
As this is a first floor apartment we can only imagine they had access to the ground floor area below to provide temporary works to the floor as they cut out the floor bearing length and inserted the new bottom beam.
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Overall there were quite a few splice connections within the bottom beam (most likely for ease of installation) and the two intermediate columns span between top and bottom beams. Their column connections were nominal, so can only assume the end column connections provide the bulk of moment resistance to replicate the wall stability removed.
This couldn't have been a easy build, so props to the contractor whoever they are - it's a good effort.
On a side note, this is also the kind of thing that could make or break an airspace scheme should the freeholder of the property wish to vertically extend in future. Those long span beams may not have the ability to sustain an extra floor of load.
Associate Director, Structures, Bureau Veritas Building Control, supporting my Building Control Surveyor colleagues. Fellow of the ICE. Lead author of "Structural Robustness and Disproportionate Collapse in Buildings"
2 年Sean, When I was doing Party Wall work in London I was involved in a scheme which involved multiple walls being removed in an Holland Park mansion flat. The contractor did an amazing job with temporary works and all the steelwork went in safely. However, there was still cracking to the flat above. Everything had been done 'properly' (Party Wall notices, Licences to Alter from Freeholder etc.), and therefore the damage was sorted by the PW surveyors. But, I do find it odd that schemes go ahead where all the professionals know that there is likely to be damage to neighbours. I am never sure that the neighbours know though! It's great that the damages are resolved but it is still stressful being that neighbour.