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Feature article


A Structural Engineer’s Viewpoint.

WORDS BY Phil Gardiner

There have been huge advances in technology over the last 150 years which have influenced Victorian architecture, but how much?

The rolled steel sections we use today were starting to be introduced in 1902 and were well entrenched by 1924 when Dorman Long won the contract to build the Sydney Harbour Bridge. Even our section sizes are still imperial conversions for most steel beams and columns.

Reinforced concrete for structures was developed by Monier and others in the 1870s and adapted by John Monash in Melbourne in the early 1900s. Although material qualities and placement techniques have developed greatly, it is still fundamentally the same. Other building technologies such as elevators and air conditioning may well have had more impact on the way buildings are designed than the progression of structural technology.

So what has changed? Bolts and welds have replaced rivets, higher steel strength, ‘COR-TEN’, stainless steel and tubular sections have been developed. With concrete, the commercial strengths have increased by factors of 10, reinforcement has improved in strength and ductility and we have post tensioning and precast concrete systems. Although these are hardly new; the first prestressed bridge was built in Germany in 1938, and Frank Lloyd Wright and Burley Griffin used precast systems in the early 1900s. The future may bring us commercial geopolymers, ultra-high strength concrete (Ductal) and other new materials.

In reality, what has changed is the imagination of designers and the technology available to analyse and construct each concept. If we take the history of our own practice, founded as W.L Irwin & Associates in 1953 as a starting point, and the work undertaken since that time, I believe the changes in the use of technology by our local designers can be demonstrated.

Pre-Second World War, Melbourne had produced many fine buildings and designers, but was predominantly delivering more classical structures using technology that had been in use for many decades. There are differences in the design solutions, such as the Capitol Theatre and Newman College by Burley Griffin, which created different forms using traditional materials and methods (his ‘knit lock’ precast system may be a real technological change).

Post-Second World War Melbourne saw a new creativity following a trend of similar freedoms that developed in Europe after the First World War. Skilled labour with a different view of the world returned to our industry that was still affected by austerity measures and shortages of steel and energy. This is the decade in which John Connell, Bill Meinhardt and Bill Irwin established enduring practices in Melbourne. These consultancies subsequently spawned most of the other practices formed in Melbourne.

Labour intensity with minimal material content was, for this period, the driver for many designs. Bill Irwin was fortunate to team with McIntyre, Borland and the Murphy’s on the design for the Melbourne Olympic Pool, where a conventional steel and concrete structure was conceived in a unique and minimalist way. Form absolutely represented the function, this world’s first prestressed structure utilised sprung tie down rods to prestress the main trusses supporting the seating plan and roof. The elegant glass curtain end walls were also a new technology for Melbourne, perhaps best demonstrated by ICI House, designed by Sir Walter Osborn McCutcheon.

Produced in the same era with structural design by in-house engineering director Harvey Brown, ICI House replaced the T&G building and the St Pauls Cathedral Spire as the tallest building in Melbourne and also incorporated precast floor structures and a side core. It was well ahead of its time.

Bill Irwin was joined in the 1950s by the brilliant young graduate Ron Thyer and by V Roy Johnston, a more experienced engineer who also had qualifications in advanced mathematics. These skills were certainly put to the test on Barry Patten’s Sidney Myer Music Bowl, a pioneering tensile structure conceived and delivered over a decade ahead of Frei Otto’s similar structures.

In the spirit of minimalism, the form of the bowl canopy represents mathematical purity of engineering form and was also influenced by aeronautical and materials science input from the Aeronautical Research Laboratories and CSIRO. I am still amazed at the brilliance of the engineers who analysed this structure without the aid of even a calculator, let alone a computer.

Anecdotes tell us that Roy spent a lot of time modelling the cable catenaries by hanging strings on a wall to develop the geometry. The skin also relied on newer technologies with ‘Alum-ply’ panels formed by bonding aluminium sheet onto plywood, a development of earlier skins used for aircraft. The fabricated steel columns enhance the overall elegance by employing a structurally pure cigar shape with narrow ends and a broader middle, putting material where needed to resist buckling.

The State Library had a concrete dome in 1911 (Bates Smart with John Monash) but modern monolithic thin shells really came about in the 1950s when Boyd with Bill Irwin gave Melbourne a suburban version on the High Street; the Jordanville shops. Like the Olympic Pool and Sidney Myer Music Bowl, these structures represented a structural purity. Sir Roy Grounds’ Australian Academy of Science Dome in Canberra was completed in the same era.

The next real technological change perhaps came in the 1960s. Work on the modernist BHP House by Yuncken Freeman & Partners commenced in 1967, with John Fowler of Irwin Johnston & Partners working with Fazlur Khan of SOM on the structural design for the 152m tall tower, at the time the tallest in the Southern Hemisphere.

The ‘core-and-outrigger’ system adopted for BHP House emerged internationally in the mid-1960s but this building was the first to use a steel framed system of core, outrigger and belt trusses. BHP House also utilised permanent steel deck formwork (Bondeck) for one of the first times. Complex mathematics was required to model the structural stiffness under windload and the oral history tells us that this analysis was done on a MIT mainframe computer used by the space program.

Perhaps equally interesting is the advice from John Fowler that the computing power of this main frame was virtually matched by the Commodore 64, a pioneering home computer that sold for US$595 in 1982, only 15 years later. Nevertheless, what we were seeing in the late 1960s and 1970s was the introduction of real computing power into building design and the resulting ability to analyse more complex structures.

Melbourne Olympic Pool,

Images courtesy of Irwin Consult.

Academy of Sciences,

Images courtesy of Irwin Consult.

Sidney Myer Music Bowl,

Images courtesy of Irwin Consult.

140 William Street,

Images courtesy of Irwin Consult.

Estates House at 114 William Street, also by Yuncken Freeman and Irwin Johnston, followed, but in concrete, as did Eagle House with John Connell as engineers. This was also the time of the invention of the self-climbing tower crane by Favelle in Melbourne. The Favco, or Kangaroo Crane as it was known in the USA, became a common sight across Melbourne’s construction sites, providing quick and safe lifting and the ability to climb with the building. These cranes became most famous during the construction of the World Trade Centre towers and are still used extensively today.

The modern era now saw tall buildings in mainly concrete, or steel with glass and aluminium curtain walls as commonplace. Precast panels were also in greater use. A beautiful example of this technology is the State Government Offices in the Parliament Precinct by Yuncken Freeman and Irwin Johnston & Partners. These classically proportioned buildings designed and built in the 1960s used load bearing precast panels for the first time on a building of this type.

Precast concrete also found its use in high rise residential structures – developed by the Ministry of Housing – across inner Melbourne in the 1960s, following the success of the ‘Concrete House Project’ started in the 1940s.

Moving into the 1970s, the emphasis shifted to minimising labour on sites for cost and industrial relations reasons. Construction time also became much more of an issue. The State Bank Building by Eggleston McDonald & Secomb and Irwin Johnston & Partners at 385 Bourke Street was commenced in 1975 and certainly used more computing power for its analysis. By this time we had a telephone line link to a main frame in St Kilda Road and sent our data ‘down the line’ on pencil marked cards. It took several hours to mark the cards and 20 minutes to walk to the bureau to find you missed a comma and the run had failed. The real technological advances here were construction related; the building progressed quickly with a jump start on erection columns to allow the tower to commence whilst the podium was constructed. This technique is finding favour again today.

The steel framed floors were also protected against fire with a ‘non-asbestos’ fire spray for the first time. Following this building, Melbourne became a ‘concrete town’ and was amongst the leaders in the world for the development of very high strength concrete – column strengths of up to 110MPa were achieved in the late 1980s. This reduced column and core wall size which is essential for efficient floor plate design. The Rialto Tower by Perrot Lyon Mathieson with WL Meinhardt Engineers was the leading example at the time, along with other tall towers at 101 and 120 Collins Street, and subsequently the Eureka Tower in the 1990s.

In-house desktop computing gave us relatively enormous analytical power in the early 1980s for everything except finite element and similar complex systems. Irwin Johnston & Partners introduced our first ‘desktops’ in 1981 and used them and their next generations to successfully deliver the design for Parliament House Canberra for Mitchell Giurgola & Thorp. A massive building with enormous complexity, the task would have been difficult to comprehend without computing. A recent paper in ‘The Structural Engineer’ by Allan Mann of Jacobs (UK) titled ‘Insight Not Numbers – A Brief History of Computing in Structural Engineering’ gives a good account of the development of computer aided analysis from the early 1950s to the current day. As this developed further it became possible to draw, set out and construct more complex geometries releasing more creative opportunities.

The 1990 recession killed off the big concrete office projects and pushed the focus back to smaller and public buildings with a greater emphasis on design. Mathematical forms came again in the 1990s, expressed in ARM’s Architecture’s façade treatments for Storey Hall and Promedicus. The Promedicus façade followed a geodesic dome form with Irwin Johnson & Partners setting up a mathematical algorithm to generate the geometry and set out to facilitate the structural analysis. Materials did not change much in the 1990s.

The new millennium saw the reintroduction of timber into mainstream buildings. The use of sustainable forest products combined with technology to manufacture these into laminate veneer lumber (LVL). Laminated beams and cross laminated timber (CLT) emerged with the Forte Building by Lend Lease, demonstrating what could be done with CLT, and The Library at the Dock by Clare Design + Hayball. Our own work on The University of Melbourne, Melbourne School of Design for John Wardle Architects and Studio NADAA also products for the hanging studio and atrium roof. Local commercial manufacture is essential for these to become mainstream products. Other manufactured timber and timber/ steel composites such as ‘posijoists’ and ‘tecbeams’ have had an impact on construction methodology for high density residential with midrise buildings such as The Green at Parkville by Australand (now Frasers Property Australia). Using manufactured assemblies of floor cassettes and wall frames sped up construction and reduced site labour.

Offsite manufacture has been through a major thrust of technological development in recent years, whether it be façade elements, floor components, building services assemblies or whole modules; such as Fender Katsalidis’ Little Hero and DesignInc’s Nicholson St. projects built by Hickory. The use of ‘Advanced Manufacturing Concepts’ drawn from the automotive and related industries to produce buildings and building components under factory conditions should continue as local manufacturers keep investing in this space.

The second decade of the 2000s has seen continued growth in computing power and what we can do with it. 3D drafting and BIM are becoming the norm, which has brought with it the need to analyse complex structures in 3D more efficiently. Parametric modelling of structures, once the prevail of major institutions such as Arup, is now possible at desktop level. This provides the ability to transfer models for analysis via Grasshopper from Rhino and other graphical design tools, directly into structural analysis packages for rapid assessment of alternatives, which gives even more freedom to designers to work with unusual geometries. The future will undoubtedly bring more developments in this area; if the last 30 years are anything to go by, the next 30 years will exceed our imagination.

3D printing of simple building structures is already possible. The commercial development of sophisticated ultra-high strength concretes and geopolymers that can be placed robotically is surely coming in our lifetime. How this impacts the design of buildings rather than just the efficiency remains a big question. Looking at how technology has been adopted and adapted by Melbourne’s design professionals over time should instil confidence that architects and designers will always find a way to use new technologies in a creative way.