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Concrete In Australia : December 2008
PERSPECTIVE Tribute to a creative structural engineer Line honours for the fastest time in the 1973 Sydney to Hobart Yacht race went to a yacht named Helsal. This would seem to be a fairly uninteresting matter other than for those of the Australian yachting fraternity except for the fact that Helsal was constructed from concrete (called ferro-cement in boatbuilding circles) and which earned the nickname The flying footpath. The choice of concrete for the construction of an ocean racing yacht would seem to be ludicrous were it not for the fact that the structural design consultant for Helsal was a structural engineer named Peter Ellen. He was one of Australia’s truly innovative structural engineers. Following his death about two years ago called as a Supreme Court expert witness where his specialist knowledge was highly valued. In 1986 he received both the Gold and Silver awards at the International Association of Shell Structures Conference in Osaka, Japan, for his developments in post-tensioned steel structures and subsequent steel and concrete composite construction. In 1987 he was guest Civil Engineering Peter Ellen … designed more than 250 structures in 14 countries. in Sydney, his family and friends honoured his life and work. However, this is the fi rst time Ellen’s story of lifetime achievement has come to the notice of Concrete in Australia. A New Zealander by birth, Ellen graduated from the former University of New Zealand in 1952. From 1952-55 he was employed by the Dunedin City Corporation. Following this he became Design and Development Engineer to the New Zealand Portland Cement Association. From 1962-67 he was a senior lecturer in structures at the University of NSW. A sign of things to come was his design and construction of a pre-stressed concrete diving board in the university’s concrete laboratory at Wattle Street and the design and supervision of construction in concrete of the Ellen family residence at Turramurra. It is believed this was the first pre- stressed concrete private residence constructed in Australia. From 1964-67 he worked for Lift Slab Australasia and in 1967 he formed Elstress, a design, consulting and contracting company in Sydney. Ellen moved to Hong Kong in October 1973 and established the design fi rm of Peter Ellen & Associates Ltd. Here he specialised in steel and concrete structures, particularly the designing, full-scale testing and construction of developments in Australia, the Philipines, Hong Kong, China and Japan. Peter Ellen was an expert on the modes of failure in both high-rise and low-rise buildings, particularly with reference to earthquakes. He was the author of over 80 technical papers and 15 unpublished reports of building failures and failure tests. He specialised in fracture mechanics of materials, particularly concrete, and developed new types of steel strand, reinforcing bars, and high strength concrete (over 200MPa). He was also the holder of many patents relating to structural systems and concrete technology. As a consequence of this he developed particular expertise in the application of advanced pre-stressed/post-tensioned technology to large-span and space structures, concrete and steel bridges, concrete pavements, marine structures and deep-sea structures such as the Norwegian oil platforms. He was often 16 Concrete in Australia Vol 34 No 4 Graduation Day lecturer at Cambridge University, UK on post-tensioned steel and fracture mechanics. In September 1989 he presented the Asian area Representative paper on “Membrane Space Structures” in Madrid on the 30th Anniversary of the International Association of Shell Structures. In 1991 he was invited to join an overview group to assess structural performance for special structures with Prof Fritz Leonhart of Stuttgart, Germany and Prof Heinz Isler of Burgdorf, Switzerland. During the period 1993-2002 Ellen was largely devoted to the development of high performance commercial concrete (50-150MPa) and its free fl owing properties to enable high productivity. Of particular note is the 40,000m2 floating, joint-free, 747 aircraft apron slab at Penang Airport. Other developments during this period include highly pumpable Portland Cement Grouts (80-10MPa) to seal and strengthen many kilometres of undersea tunnels. Grout pump lines exceeded 4500m and pumped over 600t of cement. Also in this period Ellen was invited to speak at New College, Oxford on topics such as Load testing and repair of bridges (April, 1997); Developments in pre-stressed concrete structures and, ironically, The use of the Thrust Line system of structural analysis to improve the effi ciency of explosive demolition and dismantling of structures (September, 1998). Ellen had more than 40 years experience in the practical implementation of his techniques, having designed more than 250 innovative, cost-saving structures in 14 countries. All of these structures had met or exceeded specifi cations, were within budget and to this day continue to give excellent service. He returned from Hong Kong to live in Sydney in 2001. He was an Individual Member of the Concrete Institute of Australia and a frequent attendee at technical meetings held by the NSW Branch of the Concrete Institute of Australia. He was a Fellow of the Institution of Engineers, Australia in addition to becoming a Life Member of the Institution of Professional Engineers of New Zealand in 2002. He had also been a member of the American Concrete Institute ACI Committee 125 Concrete technology in space applications since its formation. This committee produced Lunar concrete for the design, development and establishment of lunar moon bases. Source: the Ellen family, Sydney.