The perimeter beams and columns are interconnected so as to function as an external framework, thereby integrally resisting a major portion of the lateral forces and controlling the dynamic performance of the structure. Computer-aided design is programmed to include such factors as member sizes, concrete strength and reinforcement ratios; temperature, humidity, loading conditions and age of loading; shrinkage, creep, column and facade shortenings; wind and movement effects, meteorological and model-testing data.

The twin-tower complex is effectively constructed by incorporating prestressing cables in a high-rise tower from levels 1 to 38, for subsequent stage-stressing purposes when the integrated sky-rise tower alongside is being built segmentally to the upper levels of the project. In this way, all columns below level 38 are subjected to similar loadings at the same time and the elastic and non-elastic shortening values are kept relatively consistent for the lifetime of the structure. Melbourne, Victoria, 1985 (Fig. 12).

12 Rialto Building Project, Melbourne, Victoria

Concrete construction in remote areas has frequently called for technical ingenuity and supplying aggregates of adequate quality at an economic price. As a solution to a particular problem on the Weipa Bauxite Project in Northern Queensland, consulting engineers Gutteridge Haskins & Davey designed a concrete mix based on the use of graded bauxite aggregate in combination with local sands to produce a structural concrete capable of being utilised for all building works, foundations, etc. for the facilities required for the Weipa Bauxite project. A test programme established feasibility and eventually bauxite concrete was used in all structural concrete work at Weipa, including a major bridge superstructure. In exposed conditions the surface was coated with tar epoxy to prevent ingress of salt water and potential deterioration of surfaces.

Notwithstanding the friable nature of the bauxite aggregate, the concrete has performed well and after 15 years in service shows no signs of major deterioration.

The use of bauxite concrete in the project reduced the cost of concrete by in excess of 30 per cent, which resulted in a major saving over the life of the project.

Another contribution to concrete technology by GH & D, was the application of gunite facing to the upstream face of the rockfill dam for Mt. Isa and Mary Kathleen Water Supply in the early 1950s. This provided a simple economical form for construction for locations lacking impervious core material.

Australian Academy of Technological Sciences and Engineering