Flat slab construction carries with it the inevitable risk of punching failure. When loads in the stress areas are increased, careful thought has to be given to criteria such as the quality of the concrete, additional reinforcement content, even enlarging the column heads. These options are neither time efficient nor cost effective, and rarely solve the problem to an acceptable performance level. In addressing any potential problems of punching shear at the major new Anthology Hale Works tower, the solution needed to be cost-effective, easy-to-install and certainly dependable.
At the heart of Tottenham Hale, one of North London’s most diverse communities, Hale Village is a multi-award winning urban development. It already includes a mixture of private and affordable homes, student accommodation and a range of non-residential uses including a gym, supermarket, community centre and church. Hale Village has been voted one of the top 30 best regeneration projects in the UK and the most Innovative Affordable Housing Scheme. The last piece of land currently being developed is Anthology Hale Works Tower. This elegant 108 metre high, 32 storey tower offers 279 homes and over 12,000 sq ft of mixed commercial use. There is a selection of studios, one and two-bedroom homes with other features including a 24-hour concierge, resident’s sky lounge and garden, expansive landscaping and private balconies. The striking design of the tower will act as a landmark for Tottenham Hale and Hale Village, whilst simultaneously achieving the highest design and environmental standards.
The prevention of punching failure is critical though
With flat slab construction and the increasing trend for thinner slabs, there is the inevitable risk of punching failure around column heads. So when loads in the stress areas are increased, consideration has to be given to issues such as the quality of the concrete, additional reinforcement content, even enlarging the column heads. These options are neither time efficient, or cost effective and rarely solve the problem to an acceptable performance level. Construction at Anthology Hale involves a single-storey basement box, partly situated above a live London Underground tunnel and bordered on one side by Tottenham Hale station, and existing buildings to the other three sides. The 32 storey building has a jump-formed core and concrete frame, with the first six levels being acoustically separated from the basement structure, due to the adjacent London Underground line. First and foremost flat slab floor is an economical form of construction, but it offers other benefits as well. The minimisation of shuttering time for example, simplification of reinforcement work, ease of underslab work such as ducting and just as importantly, the optimum use of space. However, with flat slab construction the risk of punching failure is always a critical issue. When increasing the loads in the stress areas, a great deal of consideration has to be given to variables such as the quality of the concrete itself, improving the reinforcement content and even enlarging the column heads. None of these options is necessarily time efficient or cost effective. They rarely solve the problem to an acceptable performance level either. So the ideal solution to resolving any potential problems of punching shear needs to be cost-effective, easy-to-install and certainly dependable.
Increased shear force resistance of around 70%
The reinforcement system used to prevent punching failure at Anthology Hale Works is the widely used Schöck Bole system. This reliable and trusted solution consists of double-headed studs and anchors, with spacing bars, which enable installation after the bottom reinforcement and before the top layer. Two spacer bars are welded to the vertical studs, which ensure the correct distance between uprights; and the forged stud heads guarantee a perfect finishing bond with the concrete. When compared with a typical stirrup reinforcement system, an increased shear force resistance of around 70% is achievable. It is a genuinely cost-effective and timesaving solution.
Other variants – plus Schöck design software too
In addition to the standard Bole solution, Schöck has developed three other punching shear reinforcement variants. The type U is a solution designed for installation before the lower mat; the type O is for installation after the top reinforcement layer; and the type F is designed for use in element slabs at prefabricating plants. The entire range is supplied ready for installation and provides a totally reliable solution to the problem of punching shear in flat slabs. There is downloadable user-friendly Schöck design software available too, which enables fast and simple dimensioning of the product to British Standards and the export of CAD drawings with dxf-format.
For further information on the Schöck Bole system contact the company on 01865 290 890 or visit www.schoeck.co.uk