Architectural – 140 William Street is one of the most noteworthy building designs by the Melbourne firm Yuncken Freeman.
Technological – Its innovative structural application of steel and concrete, leading to open floor plates that are now a standard feature of high rise office buildings.
Containing 41 floors and standing at 152m tall, BHP House was designed in a ‘Modern Style’ during the 1960s. The design was promoting the use of steel in Australian construction and sought to establish new national height standards for a steel-framed structure. Consisting of three dominant materials - steel, concrete and glass - BHP House was the tallest building in the city upon completion. The building's expressed gridded structure was a clear break from the sheer curtain walls of the 1950s and 1960s, and like the pioneering skyscrapers of Mies van der Rohe, it was designed as a three dimensional sculptural monument, detached from the surrounding cityscape. In the architectural field, BHP House is regarded as one of the most notable projects by Yuncken Freeman Architects due to cutting edge techniques for an office building such as flush glazing, minimalist interiors and expressed structural bracing. Yuncken Freeman carried out a series of experiments for the design proposals of BHP House in the construction processes of their own offices in 1970, located at 411-415 King Street, Melbourne. Under the advice of Fazlur Khan, a structural engineer from Skidmore, Owings and Merrill, the design revolves around four basic components in order to reinvent the tower as a ‘cantilever’ and achieve the properties of a ‘giant stiff structural tube’. The four components consist of a steel-framed flooring system, a steel-framed central core, a steel and glass façade, and steel trusses that connect the central core to the façade. Innovative techniques were employed to lay the foundations of the building – a concrete raft which was poured in a single continuous action. The weight of the floor structure was reduced by using open-web steel beams and a lightweight layer of concrete. Along with cap and belt trusses, this flooring system performed a stiffening effect and allowed structural loads to be transferred down through the central steel-framed core and the outer steel-framed façade, eradicating the need for internal columns and providing flexibility for internal spaces. The design of the building was also notable for the ‘total energy system’ which allowed electrical generation using BHP natural gas. BHP House set the standard for many subsequent office buildings and led to the change of Melbourne Town Planning Codes which were altered to cater for increased building heights and floor areas.
