The tender specified a large sign on a new steel structure with claddings surround. The many aspects that affected the final quality of this product are outlined below.
The Prismaflex sign ordered early as it was on the critical path for delivery. It was ordered exactly in accord with the tender specification and measurements. Clearly, the supporting structural steelwork needed to exactly meet Prismaflex’ critical measurements and requirements. Also, given the sign size, easily adjustable vertical and horizontal attachments would facilitate “fine tuning” on site. The cladding connection to the structural steel and Prismaflex sign was designed so most work could be completed off site so the cladding could easily be clipped on and fixed on site.
Selection Quality Sub-Contractors
Contractors for the manufacture and fitting of structural steelwork and cladding were selected based on industry reputation, their ability to demonstrate quality illustrations, their ability to meet our stringent timelines and price.
Understanding Critical Features and Tolerances
Andersal, Prismaflex, Wexford and Facade Innovation representatives met early on site and communicated frequently to establish (under Andersal guidance) the key elements for interconnection.
Matching the Existing Structure to the Design
Andersal conducted the first survey of the car park while the brick wall was still in place. It was apparent the client drawings had a 100mm error in both total width and height. It was also apparent that large rise and fall variations (sometimes 60mm in a few metres of length) occurred in the floors. Furthermore the floor and ceiling were skewed in each plane. Based on this, Andersal commissioned a surveyor to measure floor and ceiling reference levels at each proposed column position – 12 per floor or some 96 survey points.
Using this data, Andersal produced a vertical offsets chart for Wexford and Facade Innovations to enable each to manufacture every component to an exact measurement.
Andersal proposed early (without additional charge to City of Sydney) that we provide a hot dipped galvanised structure rather than a painted structure as was specified in the tender as this would have superior quality and durability. We selected Wexford to manufacture and install. Andersal visited the factory twice to inspect production and inspected the galvanised steelwork delivered to site and organised for the sharp galvanising edges to be removed before construction.
Wexford laser measured the structure based on Andersal design and reference points to establish all vertical locations and anchor holes. This formed the basis for the structure and was accurate in each plane.
Almost all the 3000 bolts connecting the 1000 individual steel pieces were rattle gun tightened to ensure correct tensioning. Surveys indicated the 5 storey by 37m box is within 13mm of true – a very good result. The most critical criterion we specified was that the bottom horizontal be flat. The 37m base structure was installed uniformly horizontal within a 2mm tolerance – an excellent result. In addition Andersal’s steel work design allowed an extra 25mm vertical or horizontal adjustment if required.
Prismaflex sign was assembled in twenty banks. They started from the bottom and built to the top. The bottom two levels are driven from motors at the bottom, and the top two levels are driven from motors at the top. The control panel was installed on the first floor level. The first bank in each level was installed and then was micro adjusted 1 or 2mm so it just fitted a prism tightly. The rest of the horizontal level was lined-up with the first bank. This process was repeated for each floor for a total of 1200 prisms.
Independently from Prismaflex, Andersal checked that the prisms on each level overlapped the triangular swivel connectors sufficiently. The overlap was always more than 20mm.
The electrical wiring was installed with protective conduit and cadmium coated attachment screws that met Australian Standards, however, Andersal had these screws replaced with stainless steel screws for better durability to match the life of the installation.
Andersal selected Facade Innovation to manufacture and install cladding.
There were 150 panels installed each connected to the structure from the inside with 6 screws so that no fittings were visible from the street. The panels were produced off site with a protective removable coating and scoured so that they could easily be bent sharply on site. For example, each vertical panel was bent on site and then connected by the workers in the swinging stage and on the extended platform on each level. The first panel was placed, adjusted to be vertical in each plane, packing wedges inserted between the structure and the cladding and the panel was then connected. The panel was then disconnected one screw at a time, the protective coating removed from under the screw and the screw was retightened and correctly tensioned using a power screw driver. This process was repeated for each screw, then the vertical was checked again in each plane and a final adjustment made if necessary. This was repeated for the next panel which was of course lined up with the first. A similar process applied for horizontal panels. This very meticulous process was necessary to achieve the clean cladding lines.
It was important during the total construction process that all site workers (particularly abseilers) were briefed, supervised and checked not to damage the critical elements, especially the tri-prisms and the final cladding surfaces. Surfaces vulnerable to graffiti were left with protective coating intact until after security partitioning walls were installed just prior to handover.
Andersal selected Lidoran Roofing to install the partition walls on each floor separating the car park from Prismaflex sign. The selected construction was a steel frame with metal Colorbond panels and a high quality 2 hour fire rated lock. Andersal paid 10% extra to ensure quality finish.
Defects Liability Period
The contract allowed for the normal industry 12 months Defects Liability period. There were no defects at all requiring attention in the 12 months from Practical Completion to the end of the Defects Liability period.