The Travellers Sandridge Bridge Redevelopment The Travellers : Sandridge Bridge Redevelopment The Concept In 2001, the City of Melbourne Council held a competition calling for ideas to redevelop the existing (and disused) historic Sandridge Rail Bridge.
In 2001, the City of Melbourne Council held a competition calling for ideas to redevelop the existing (and disused) historic Sandridge Rail Bridge.
Nadim Karam with Atelier Hapsitus proposed a cultural interpretation called “the Travellers” – consisting of 12 large scale sculptures that move across the bridge. These represent a celebration of different historic periods of immigration to Melbourne.
10 No stainless steel sculptures (approx 7m tall x 5-10m wide)
Bogie mechanism and infrastructure to facilitate movement of sculptures across the bridge
$2M construction budget, 9 month delivery programme
Must be delivered prior to 2006 March Commonwealth Games
Arup Melbourne commissioned to provide structural, mechanical and cad design services.
Establish and rationalize geometries of sculptures using a family of parametric curves, working from the artist’s concept sketches.
Confirm structural adequacy of proposed sculpture forms
Provide information to fabricators in electronic format to enable fabrication.
Develop concept design of bogies and assist bogie manufacturer with final detailed design.
Develop performance based specifications for infrastructure installation to bridge for Travellers.
Sculptural/ Structural Forms
2 No. identical planes, joined together using diagonal members following an arc projected from the planar form
Perimeter members typically 80x80x3thk SHS
Internal planar members typically 40 x 40 x 3thk SHS
Diagonals typically 38 x 3.2thk CHS
Orthogonal members around perimeter typically 48 x 3.2 CHS
Sculpture and structure “one and the same”
Overall process overview
Internal Design Cycle
Geometric Translation (2)
Free-form spline geometry received from the architect was rationalized into a standard set of arcs and straights in Rhino via an automated routine
Prior to export from Rhino, all arcs in the model were rebuilt as a series of lines, and all lines were checked for nodal connectivity.
Wax print and 1:1 steel prototypes were used to understand the interface between geometry, analysis and fabrication
The data required for fabrication was automatically stripped from the 3D model using VBA and tabled as spreadsheets. With this information, no drawings were needed for steel fabrication.
Geometric Translation (3)
Custom Rhino and VBA scripts were developed to generate entities within the 3D model, and to translate data between different processes.
The requirements of fabrication and analysiswere used to structure the geometry generation, which avoided later
rebuilding and cleaning of the 3D model and other translation difficulties.
Structural Analysis and Design (1)
All sections from stainless steel 316L
Sculptures have been assessed using the “Dallard” method of buckling analysis. Typical buckling lambda values of order of 20. Modal buckling analysis used to calculate modes of failure and corresponding buckling load factors (lamda).
Primary live load is wind loading. Effective solidity typically 25%.
Structural Analysis and Design (2)
Natural Frequency typically >4Hz
Stiffness of sculpture frames derived from triangulation of most members and relatively short individual member lengths.
Full continuity at all connections
Structural Analysis and Design (3)
GSA derived combined axial and bending stresses C1 and C2 used to quickly establish stress state within each sculpture. Allowable stresses reduced according to qui buckling factor.
Spreadsheet information and cad files fed directly to fabricators - Shop drawings were not required,
1 to 1 templates derived from cad files used by fabricators to ensure correct member fit during fabrication
Tight radii formed using plate sections (8mm thick) which were fully welded.
All member to member connections FSBW (TIG welded) All welds ground back and polished.
Fixing to Bogie
Sculptures fixed to welded platform which in turn is bolted to 323 dia spigot member. Spigot member supported by roller taper bearings at base (to support vertical load) and roller thrust bearings at top (to support horizontal loads)
Prototype assembly tested for static 100kNm moment during trial horizontal and rotational movement.
Total length of steelwork = 3.77km
Average sculpture weight = 2.3t
Heaviest Sculpture = 7.7t
No. Steel elements = 4455