A flavour of Mace projects in the city
Last week I visited 5 Broadgate which is another Mace site. It is right by Liverpool Street Station and is prime banking territory. UBS is having built a 700,000 sq ft building, based on a single block form, with a gun- metal grey finish. At 12 floors it will include up to four trading floors, each able to accommodate approximately 750 traders, allowing UBS to consolidate its London trading operations into one building.
So here is the problem:
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In order to overcome this issue the corner would be hung from a truss on the roof as well as Macalloy hangers on the 1st and 2nd floors.
Here is a picture of the 3rd floor with the Macalloys in use
The (big) truss on the roof cantilevers out to allow the perimeter column to hang in tension and suspend the corner. Jacking was used to ensure it had ‘picked up’ the perimeter.
This system seems to have worked well on site. It is reasonably simple to set up and control (with jacking). Mace plan to pour all 11 floors of corner concrete at once so that there is no differential movement between the floors. The Macalloys and roof truss will be ‘stressed’ so that any elastic extension is accounted for with pre camber.
On the South Bank Tower we will also be using Macalloy cables, but ours will be used in the permanent design. The proposed force in them will be 7600kN. Anyone else got any experience with them?
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Great explanation and diagrams Richard. The ‘Temporary Solution’ diagram shows the effectively proped cantilevers nicely hanging from the Macalloy ‘props’ and the outer columns doing nothing (tension above the lower two floors from the truss but nothing at the lower levels). I am reading the final condition as being without the roof level truss and each composite floor cantilevering out. If this is the case, surely the corner columns will only ever act as a tie to ensure an equal distribution and even deflection (Not quite as per the Permanent State digram). This surely means that it would have been possible to omit the corner column from the permanent state altoghter; quite a sexy, if less robust, option. And perhaps the answer lies in that last thought… I do like this explanation of a temporary works plan – good stuff.
Pretty neat…don’t quite get the jacking bit AND ( Mr Picky!) I think that there should be a compressive force into the beams from the Macalloy ties in the temp condition
I can see what Richard means…seems that the edge columns would be doing a similar job in the temporary condition and if called for in robustness… so would just help form large Vierendeel cantilevering beams beams if a main compressive column went missing
Rich
An ideal topic for you to drop in to for CPR if the conversation so warrants it. Excellent input
Kind regards
Neil