Construction World March 2015

STEEL CONSTRUCTION

BEAUTIFUL STEEL Paragon Architects was approached by Investec during 2011 to propose a design to accommodate amongst other tenants, the law firm Fluxmans. In keeping with the mores of Investec and the tenant, a classical architectural approach was adopted, although the language was not that of classical architecture.

Following a discussion with the local residents’ group, a design evolved that comprised a raised platform at street level that included parking but was expressed as a planted volume. Most of the plants, especially the trees were pre-grown so that once they were planted during October 2013, they had reached some level of maturity. They included: Acacia xanthophloea, Celtis africana, Viburnum sinesis and Ficus microcarpa. Access to the street was to be welcoming. Sitting atop the platform were the offices themselves, that were heavily screened to the east and west with deep overhanging sun screens on the north. Steelwork forms The steelwork forms and integral part of the design and the engineers developed a language that was as elegant as possible. The columns are 24 m long in a single length and from the 5 th floor to roof they taper to 250 mm from 500 mm. There are 12 columns externally and 16 internally. The sunscreens were designed from a series of sun studies executed by the mechanical engineer and internally the orientation of the blades directs your gaze to the treed residential suburbs beyond. Revised fire regulations required an extra staircase and this was included in the architectural design. Glazing The glazing formed an integral part of the design and included the following glazing specifications: AGC: double glazed Stopray clearvi- sion 50T, spandrels with clear glass, double glazed back painted unit and 3,85 m high ground floor vision panels. The biggest unitised glass panels are 4,5 m x 1,4 m. This office building is located on Jellicoe Avenue close to the corner with Oxford Road. It is essentially on the border with Dunkeld, which is a residential area. There was close co-operation with the local residents and this was taken into account when designing the five storey, 10 000 m 2 building. The simplicity of the steel structure supports the large over sailing concrete roof while the monolithic nature of the pristine white north wall that floats above the ground with the help of the steel structure behind stands in contrast to the fineness and delicacy of the steel louvres on the east, west and north that takes grates care in displaying its textured, soft nature. The basement also enters the mix to create a green, textured podium for the structure to occupy. Why steel was chosen For the columns, tubular steel was chosen to keep the structure as slender as possible (due to the stiff nature of tubular steel) while maintaining a smooth finish in and to achieve an automotive metallic finish. The columns were also finished off by adding a tapered section at the top which was formed by rolling flat steel sheets. The columns on the north, east and west elevations were five storeys high, so steelwork was chosen for ease of construction as >

these columns were going to be very difficult to construct in shuttered concrete over that height. Tubular sec- tions where chosen for their bending properties in both directions primarily, and also for their elegance. They allowed for the choice of the elegant taper at the top of the columns. The steelwork frame element hiding inside the northern façade was chosen to be constructed from steel- work for the same reason of build-ability. The framing structure for the brickwork substrate behind the tiles would have been very difficult to construct in shuttered concrete as an element on its own, which only

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interacts with the building at the fifth floor. The louvres that shade the building on the east, west and north elevations were manufactured from large flat steel sheets, lasercut to form interlocking louvre blades

which come together to create a ripple pattern Steelwork on this project

The slenderness and proportion of the tapered tubular steel columns give the building and elegant aesthetic that sets is apart from its neigh- bours. The ripple that is created by the louvre blades add another level of detail that finishes off the overall concept. The fineness of the steel elements work together to create a truly special building. Sustainability considerations Passive design principles were considered during the design process and the steel louvres form a major part in the east/west and north shading of office areas. The louvred profiles needed to be designed in such a manner that they could be fabricated in panel sections and easily erected on site with no welding required. The louvre blades were designed to be profiled and cut from single sheets by interlocking the faces in order to achieve minimal wastage and maintaining the integrity of the texture. Challenges and solutions The challenge was always the tight programmne. OmniStruct did a fantastic job on the steelwork’s quality considering the time implica- tions. Another challenge was to make the connections elegant and pleasing to the eye: designing with an appreciation for fabrication and transportation while keeping an eye on the end product so as not to defer the connection away from the original concept of ‘beautiful’.

CONSTRUCTION WORLD MARCH 2015