High Commendation LSAA 2018 Design Awards - Category 5 Glazing and Facades
APPLICATION OF PROJECT:
Architectural façade for dual purpose structure that is used as a large animal pavilion during the Brisbane Exhibition and as a carpark at other times of the year.
The project was a façade consisting of 1400m2 ST Gobain SGM50 open PTFE mesh and 650m2 solid Chukoh FGT800 PTFE. The façade provided an exciting architectural feature on the exterior of an otherwise bland carpark at the RNA Showgrounds. The facade included “porthole” features which assisted in creating the 50% open requirement for air flow for animal and patron comfort during the 2 weeks of the Brisbane Exhibition. The façade also provided an aesthetically pleasing exterior for the remaining part of the year when the structure is used as a carpark. The area below the carpark is used year round for festivals and events so the façade is a key feature at the RNA showgrounds.
Push-out points in the facade provide a textured look to the solid PTFE faces while the “port holes” break up the mesh face externally and give an external sneak view from the inside of the structure.
DESIGN / FABRICATION / INSTALLATION BRIEF
The aim of this project was to provide an architectural façade for the structure to enable it to be visually appealing and dual function. The structure is designed to be a large animal pavilion for 2 weeks of the year during the Brisbane Exhibition and a carpark for the remainder of the year. The façades overlook the lower festival showgrounds area and are prominent features throughout the year when other events are held. Close collaboration with the architect from the beginning of the project included production of a scaled prototype to demonstrate steel fixing points and positioning of “port hole” features along with the fabric details, welds, doublers and other fixing details. This detailed collaboration ensured that the design could be improved to suit the architects and clients desires and ensured the final fabricated products would be in line with all parties expectations.
The façade was constructed over a horizontal and vertical RHS subframe which attached to the precast concrete exterior of the pavilion structure. Fabric was raised from the ground level using pulleys and then tensioned in place. This installation system was a new system that had to be developed to allow for ground-up installation of the panels through fixed edges.
This project required significant co-ordination with other trades as it was a highly congested site with a hard finish date to be ready for commencement of the Brisbane exhibition.
Fabric panels were separated into individual bays spanning between structural steel. Load arising from wind loading and fabric prestress are resisted by the frame in the form of bending stresses. The frame itself is supported by a series of stub columns that connect the steel framing to structural slabs. The stubs on the level 4 slabs are fully fixed connections with the rest of the stubs acting as pins on vertical rollers to allow for the large slab deflection expected under loading.
The fabric also consisted of various push out points on each level and bay. This provided a challenge on the eastern and western as the supporting slabs were slopping towards the north and south. To achieve an architecturally clean look the push out stubs needed to be offset varying amounts depending on the location along the slab. The result is that fabric seams wrap around the building and run parallel to the seams below with all push out points appearing to be on the same level.
The southern façade also consists of multiple fabric cutouts 1500 in diameter. This provided a unique challenge as in depth fabric analysis and multiple scale mockups were conducted to ensure the fabric still maintained its strength and the circular cutouts maintained their shape after tensioning. The final solution consists of the SGM fabric sandwiched between two layers of PTFE doubler. Each doubler was cut on the bias and then offset 45 degree to the doubler below. This ensured that at least one layer of the double had the warp running in the tangentially to the cutout every 45 degrees.
The fabric chosen is a combination of ST Gobain SGM50 open PTFE mesh and solid Chukoh FGT800 PTFE. The initial design intent was to have all three facades as the solid FGT800 but due to ventilation requirements it was not sufficient to only have the cutouts. The SGM50 was chosen then as it is a 50% open mesh that passed the ventilation requirements and due to the PTFE coating the fabric passed the non-combustibility tests as specified in AS1530.
The steel framing was all made of structural steel work (Gr350) and was hot dip galvanized to provide corrosion protection.
The 50% open-weave mesh used on this project resulted in less fabric-to-fabric contact during fabric welding. Extensive research and development were required on seam design and strength to ensure adequate adhesion after welding. Multiple weld types and techniques were trialed and tested to develop the appropriate welding parameters for the project and to minimize any risk of fabrication errors and defects.
Open weave mesh fabrics typically exhibit far less stretch than typical fabrics, particularly with PTFE coated glass. Production tolerances were therefore extremely tight and comprehensive check measurement plans and inspection processes were implemented to review plotted materials, materials set-up prior to final welding and the finally fabricated dimension checks. Items failing these inspections were sent back for re-work to ensure that the correct geometries could be sent to site.
COLLABORATION, CONSTRUCTION AND MAINTENANCE
Detailed design coordination was carried out between MakMax, the builder, the architect, and the end client in the early stages of the project to ensure that the final design met the project requirements. A scale mockup of the façade was erected at MakMax HQ, which allowed us to fine-tune fabric compensations as required to facilitate a smooth fabric installation process that minimized handling of the delicate PTFE and also maximized installation efficiencies. The mock-up also served as a “sample submission” to the project design group, giving them an “in-the-flesh” perspective of the nature of the detailing.
Installation works were coordinated through distribution of detailed method statements, and through regular site coordination meetings in the lead up to MakMax’ installation works. The southern side of the building included an external stair case, with entry portals to the multi-level building intersecting the façade. Works were coordinated and programmed to allow MakMax to install façade panels to the extent of the planned staircase prior to the staircase being installed, eliminating any need for multiple panels, field joints, and complex installation methods.
The planned maintenance program for the structures is limited to regular cleaning (particularly after the exhibition period where large amounts of animal waste are expected to be present), and periodic inspections by qualified personnel.
Entrant: MakMax Australia
Role played by Entrant: Designer, Engineer, Fabricator, Installer
Location: Bowen Hills, QLD
Completed: August 2018
Client: Lend Lease
Architect: Shane Thompson Architects
Engineer: MakMax Australia