Brisbane Airport Rail Link is an 8.5 km elevated spur line linking new stations at Brisbane
Airport's domestic and international terminals with the city and the Gold Coast. The structure is
typically constructed using precast prestressed concrete girders up to 38m span, which are
supported on precast piles and in-situ concrete piers. Other major crossings included two crossings
of Schulz Canal and the Gateway Arterial Roads where spans up to 55m were achieved using
post-tensioned cantilever piers and "drop in" spans.
The elevated rail link required over 900 precast prestressed concrete girders of varying
length, all of which were designed using SAM. For typical spans, 2D grillages were used to allow
quick and simple results transfer between analysis and design. The grillages also allowed for the
effects of the curved track geometry, and the consideration of 'derailment' load cases. For the
more complex structures including the crossings of Schulz Canal and the Gateway Arterial Road, 3D
models were utilised so that substructure load effects could also be determined from the same
models.
SAM was also used for design of the station platform structures for which 2D models were used
to establish a more complex variety of load effects such as pedestrian loads, column loads from
the roof structures, etc. In addition, SAM was used for designing the precast floor system used
for the platforms.
The software's integrated analysis and design method for designing the large number of precast
girders provided major time saving benefits. Conventional methods would have required significant
manual manipulation of the analysis results which would have taken significant additional time,
and also increased the risk of data transfer errors.
The precast girder section used for the Brisbane Airport Rail Link was specifically developed
for the project. This was particularly well suited for SAM as a variety of section options were
able to be assessed in a short time, and detailed sets of calculations were able to be produced
(stress checks, crack control stress increment checks, ultimate limit state checks, shear
calculations and so on) for each of the girder types.
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