Care centre’s fearless symmetry

A distinctive elliptical steel frame forms the structure for Maggie’s Nottingham, designed by CZWG at the Nottingham City Hospital Campus. The centre opened in November with interiors by Paul Smith and is the 15th in the network of Maggie’s centres for cancer patients and their families.

高质量的建筑一直是玛吉中心的重要组成部分，这一点已经得到了包括扎哈·哈迪德(Zaha Hadid)、OMA和弗兰克·盖里(Frank Gehry)在内的众多建筑师的认可。这并不是说诺丁汉中心的预算太过奢侈——就像之前的许多中心一样，它的成本很低——建造成本为145万英镑，折合每平方米4000英镑。

The site was sloping and full of trees, providing a secluded environment despite its proximity to other hospital buildings. CZWG’s Piers Gough came up with the idea of designing an almost entirely symmetrical building held within a steel frame of interlocking ovals. The oval elevations give the building a friendly, welcoming appearance. Initially, the intention was to have a predominantly timber frame with a steel roof structure but it became clear that this was impractical to build given the site constraints, and a steel structure with timber infills was used instead.

“A steel skeleton to form the overall shape with a timber infill was the quickest and most economic solution,” says Gary Lynch, a director of engineer Adams Kara Taylor. “What looks like a quite complex shape is broken down into very simple elements.”

这座360平方米的建筑高11米，在钢筋混凝土地下室基座上的钢结构上层结构中分为两层。地下室被尽可能地从附近树木的根部拉回，结合45度旋转形成的悬挑，使建筑看起来像是“漂浮”在更小的地下室上。这种安排限制了从地面的视野，为游客提供隐私，避免行人进入中心。

游客通过一座钢桥进入中央大厅，向下进入双层高的区域，这里有厨房、图书馆和会议室，或多达两间咨询室、一间日间卧室和一个大型会议空间。上部区域是一个更隐蔽的区域，用于休息或私人交谈，而从厨房和客厅延伸出来的宽敞阳台鼓励游客享受树叶环绕的环境。建筑外部覆盖着绿色琉璃瓦，顶部是铝屋顶。在室内，由Paul Smith设计的五颜六色的家具和家具既舒适又能引起人们的讨论。

For steelwork contractor Shipley Structures, the big challenge was the unconventional geometry of the 40-tonne steel carcass, which was erected in just two weeks.

“There is a lot of curving on the building — the overlapping elliptical structure that creates a cantilevered effect and the roof itself, which is created in an ‘s’ shape which meets in a central raised point,” says Glynn Shepperson, a director of Shipley Structures.

“It’s beautifully detailed,” says CZWG’s Gough. He had the idea for the ovals when he was looking through a book by Maggie’s centres co-founder Maggie Keswick Jencks on Chinese gardens, on which she was an authority.

“I saw these Moon Gates which are circular holes that you walk through and I played with that as a solid form. A circle was too
high so it became an oval, which was the shape that fitted the two-storey building we’d decided to do.

“The idea was to make a refuge nestling into the tree. It is almost perverse in its symmetry. It seemed intriguing to do a building that wasn’t free-form; the landscape around it is quite loose and free so the building could become symmetrical. The conceit is that the elevations are all ovals and they interlock like a Canadian log house.”

Steel frame construction

Trusses and deck

四个大型装配式钢桁架构成结构的周边基础，一个在每个标高的基础上。这些将上部结构的荷载转移到混凝土基座上，并在建筑底部形成引人注目的弯曲效果。

This steel deck also provided a stable platform from which to build with a minimum of temporary works. Each of the four sides of the building are constructed off this deck, with a total of 24 columns within the elevation including the four corner posts. These corner columns link the lower curve to the four curved eaves beams that link to create the symmetrical and elliptical form.

Steel support is provided internally for a central lift shaft and three split-level floors. The light steel, fully bolted skeleton is infilled with straight timber members. According to engineer Adams Kara Taylor, this system provided a simple and fast construction method to create an otherwise complex shape. The timber stiffens the steel frame against wind loads and out-of-balance loads created by the slight asymmetry of the steel frame.

Cantilevered balconies

Cantilevered, steel-framed canopies project from three sides, along with a pedestrian bridge to the rear elevation that provides direct access into the building at first-floor level.

All four external frames were provided with perimeter balustrading, integral seating and are clad in a combination of glazed, timber and metal louvre panels. Of the balconies, one is a true cantilever and two are cantilevers with prop supports.

Roof contours

为了保持结构的细线效果，创造更经济的解决方案，设计中使用了S355级材质的高强度钢型材。

This provided one of the biggest structural steelwork challenges. Where at all possible on the building, curved steel was avoided but its use was essential to create the desired roof contours. Here, the eaves are formed by curved 12.9m beams.

From each corner spring S-shaped fabricated rafters that converge at a square glazed roof light at the crown of the roof. Four further curved beams link the corner of each roof light to the centre of the eaves. Otherwise, straight members are used to form the roof structure.

“I’m particularly proud of the roof. It’s really pretty and comes out of the geometry of the corners,” says Gough, adding that the similarity
to a Chinese pagoda is a homage to Maggie’s interests and background.

Corner ‘ears’

The projecting “ears” — two per corner — give the illusion of intersecting but the oval form of the main steel frame actually terminates at a concealed corner column.

Shipley Structures的Glynn Shepperson说:“它看起来确实像一个连续的圆形。”

相反，焊接梯子框架上的构件伸出来，使建筑的角落具有独特的重叠形式。

Although these appear curved, each ear curve is made up of four members tied to the corner column by three horizontals that pick up the wind load. The top diagonal member takes the load of the rest of the ear, which is infilled in timber.

Each ear aligns with the curve of the roof and the underside of the building to create an oval.