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January 2020

Taller, faster, better – London’s latest super-tower

Taller, faster, better – London’s latest super-tower 1100 750 Canopius

This article is from The Construction Index

When 22 Bishopsgate is completed later this year it will not only be another landmark for the City of London but it will also be a demonstration of the ingenuity and expertise of the UK structural steel industry.

The development comes with a flourish of superlatives: it will be the tallest tower in the financial district; it will be serviced by what are promised to be the fastest lifts in Europe; and the 57th floor will be home to the highest public viewing platform in western Europe.

Standing at 278m tall, the building will provide 118,000m2 of flexible workspace for all sizes of businesses and will house 12,000 workers, a gym, indoor market, cycle storage hub, art gallery and social spaces.

Yet this achievement will be all the more remarkable for having been built upon the remains of the previously stalled Pinnacle scheme.

22 Bishopsgate incorporates the below-ground elements of its predecessor, including three floors of basement and a raft slab supported on piled foundations. Reusing all the existing piles, which were not in the optimum positions for the new structure, meant introducing transfer structures at basement level and level two to support columns that do not have a pile directly below them.

From ground level upwards it is a steel-framed structure surrounding a large central core, with minimal internal columns ensuring long clear spans of up to 17m. Severfield was contracted to provide the connection design and then fabricate and construct the steelwork on site. According to main contractor Multiplex: “The final building will contain 17,023 tonnes of steelwork, made up of 14,593 individual pieces of steel.”

Designed by PLP Architecture for AXA IM-Real Assets and Lipton Rogers, 22 Bishopsgate presented challenges both in design and delivery. The design required superelevations and axial shortenings, and posed complex geometrical questions, particularly at the two double-height outrigger truss floor levels. Delivery was restricted to two access points: one shared pit lane on Bishopsgate and the out-of-hours use of the undershaft between 22 Bishopsgate and 122 Leadenhall.

“The floor slabs are composite with cellular steel beams, providing a diaphragm-action restraint to the perimeter columns,” says PLP. “There are three column positions on either side of the core to act as outrigger lateral stability structures. These outriggers, contained within two plant room floors, are connected to the core through storey-deep trusses.”

The basement level transfer structure supports one column that extends up to the full height of the building. The transfer structure is a 15m-long plate girder weighing approximately 97 tonnes. Meanwhile, the level two transfer structure is another giant steel member that also transfers loads from perimeter columns. This plate girder weighs more than 100 tonnes and is 14m long.

To preserve an existing access route to the basement loading bay Severfield designed, fabricated and erected a structure nicknamed the ‘Rhino’ truss because of its shape. This truss weighs around 150 tonnes and is composed of site-bolted booms, nodes and diagonals, with the heaviest node weighing approximately 20 tonnes. Two tower cranes were required to install it.

This article was first published in the September 2019 issue of The Construction Index magazine (magazine published online, 25th of each month.)

This article is from The Construction Index

City of London’s tallest skyscraper set for topping out

City of London’s tallest skyscraper set for topping out 1100 750 Canopius

This article is from New Civil Engineer and was written by Connor Ibbetson

The tallest building in the City of London will be topped out today.

Standing at 278m tall, 22 Bishops Gate Street, will become the tallest addition to the growing City of London skyline – standing 48m taller than the city’s previous tallest tower Heron Tower.

Designed by PLP Architects, WSP has worked as the project’s consultant, while Multiplex has acted as main contractor.

The 62-storey office tower will be the second tallest building in Western Europe, just behind the Shard which measures 310m.

However, 22 Bishopsgate will have London’s highest occupiable floor space, with a public viewing gallery and bar on the top floors accessed with dedicated lifts from the public lobby.

WSP took over the running of the project in 2015 at the site of the canned “Pinnacle” project, which was little more than a hole in the ground, with the basement and tower foundations renamed by Londoners as “The Stump” after former developers backed out after the project became non-profitable

WSP project engineer Alex Black-Roberts told New Civil Engineer that to keep the project viable, WSP would had to maximise the floor space within, which presented the first challenge as the existing Pinnacle foundations were too small for the final version of 22 that designers had drawn up.

“One of the biggest engineering challenges was building a much bigger building on the smaller existing foundations [left over by the previous developers],” he said. “We snitched these together with our new foundations, reusing 100% of the Pinnacle foundations and 50% of the basement, all of which was strengthened with our own new piling.

“Without building the bigger footprint on the smaller foundations, the project would have been unviable,” he added.

On the 37th floor three pairs of outriggers on each side of the building connect the steel frame to the concrete core. This has the benefits of allowing engineers to build wider floors by reducing stress exerted on the building by high winds, but also allows for a smaller core – maximising usable square footage in the building.

Logistics involved in such a tall build presented another challenge, Black-Roberts said. “For a building this size, and with over 1,000 people on site, just getting people, plant, and materials in and out, and up and down, has been a real challenge we had had to over-come with a balanced schedule for the internal hoists and [four tower] cranes.”

This article is from New Civil Engineer and was written by Connor Ibbetson

This high-tech London skyscraper is the envy of every office worker

This high-tech London skyscraper is the envy of every office worker 1100 750 Canopius

This article is from Wired written by Chris Stokel-Walker

At 22 Bishopsgate, architects have created a skyscraper with new technology woven into every aspect of the design.

London’s newest skyscraper is only the second tallest building in the UK (after The Shard), but the 278-metre tower rises highest when it comes to technology.

The 62 storeys of 22 Bishopsgate, due to open soon, build in a host of innovations, from the way the design protects pedestrians in London’s financial district against downdrafts caused by the whipping winds, to the military-designed logistics system to prevent traffic snarls around its base.

“In some instances we encountered problems we couldn’t solve and technology helped us solve them,” says Karen Cook of PLP Architecture, the company that designed the building. For instance, those winds: adding a new tower to an already complex skyline can cause the air to move in mysterious ways, and stringent planning laws in the City of London prevent new constructions from inadvertently causing wind tunnels on the ground.

PLP worked with engineers from Formula 1 to model every 10 centimetres of the building and the impact it would have on wind flows. The engineers created large-scale canopies, similar to those on the back of a race car, made out of steel and glass and ultra-high-performance reinforced concrete, to tamp down the wind flow – testing 23 different designs before settling on the best one.

The City of London was also keen to reduce the impact on traffic flows around the building: with space for vast numbers of tenants across the 1.275 million square feet of office space, and a density of one person per eight square metres, there’ll be huge numbers of people travelling to and from the building every day. The commuter crush is partly covered by the 1,700 cycle spaces in the basement, but deliveries are another problem.

A consolidated delivery management system, designed by an ex-army engineer, reduces the number of trips made to 22 Bishopsgate. “Instead of all the goods going to the building, they all go to a dispatch centre outside the city, they are offloaded, scanned for security and stored until the tenant requires them,” says Cook. A digital goods management system lets inhabitants call on supplies as and when they’re needed, delivering the goods outside of peak hours and using low-emission vehicles. This will halve the number of vehicles travelling to the building.

It’s not just the behind-the-scenes logistics of the building that are super-powered, though. Even the building’s facade is fine-tuned to tease out every last improvement. Glass with a lower proportion of iron than usual allows 60 per cent more light into the building than standard glass does, while each office unit will be assigned its own IP address so that those within the unit can intelligently alter the blinds using an app specific to the building.

Eight mobile phone beacons, part of a network providing five-bar connectivity throughout the development, will be placed on each of the 57 floors of office space in the building, able to transmit all four major phone networks – and they can be adjusted according to each tenant’s needs.

Unusually, the lifts, developed by manufacturer Otis and travelling at eight metres per second, were installed during the building process – to help 1,200 construction workers and their tools move around quickly. A biometric security system, using facial recognition software, can provide or prevent access to the building automatically, and once inside office workers using the building’s app can control everything from the ambient temperature to the level of light through the windows – as well as book meeting rooms and time in the on-site spa.

“The whole concept for the IT in the building is that it’s seamless,” says Danny Hall, of Lipton Rogers Developments, which has been overseeing the tech infrastructure within the building. Every action taken within 22 Bishopsgate will be sent into the cloud and analysed to monitor how tenants use the building. “We want the app to be a portal into the building, getting you through barriers, and a technological environment with which you can interact with the building,” he says.

This article is from Wired written by Chris Stokel-Walker