S K Y S O N G AT A S U C A M P U S | F T L D E S I G N E N G I N E E R I N G S T U D I O INTRODUCTION
CONSTRUCTION PROCESS
FORCES AND LOADS DISTRIBUTION
Steel trusses are fabricated in the steel fabrication plant. The trusses are used to connect the edges of the fabric membrane.
• Tensile Forces | Cables | Tension forces of the cables are responsible to hold the steel structure and membrane in place.
The frame consists of eight steel structures reaching 111 feet in length. These steel “legs” are constructed on site followed by the steel trusses. Diagram 1.0 Tensile Force of Cables
Conical-shaped pieces are supported by the frame which will be covered with the Teflon-coated fiberglass (PTFE) material using the crane.
The Skysong at ASU Campus is a sculptural tensile and a centrepiece for the overall development, providing a shaded centre courtyard with 4 plazas for cafes, restaurants and social interaction. The PTFE glass fabric structure is approximately 50,000 sq. ft of area and opened in May 2009. The centrepiece of the development is an enormous custom tensile fabric structure supplied by FabriTec Structures in conjunction with FTL Design Architects and Higgins Development. The frame consists of eight steel structures reaching 111 feet in length. These steel “legs” weigh about 2,400 pounds each. The structure peaks at an impressive 125 feet in the air. The frame supports eight integrated conical-shaped pieces covered with 50,000 square feet of Teflon-coated fiberglass (PTFE) material. The fabric is able to withstand 650 pounds of force per square inch once all the connection adjustments have been made. As FabriTec Construction Manager, Deon Kleynhans points out, “Once there is tension and it’s under load, it will be able to withstand the same forces as stainless steel.”
The conical pieces are secured to the rings of the frame structure and the fabric is assembled piece-by-piece once the skeleton structure is constructed.
Then the fabric is adjusted and secured to withstand forces. Once there is tension and it’s under load, it will be able to withstand the same forces as stainless steel.
STRUCTURAL SYSTEMS • Mast-supported Tensile Membrane Structure The structural system of Skysong shade structure consists of 4 A-frames. Each A-frame has 2 inclined mast joined together at the top, and a pair of bale ring at the top and bottom of the masts, forming a pair of inversed conical shape. This type of structure is used as it can economically and attractively span large distance .
Mast • The compression member of the structure
Wind
Diagram 2.0 Tensile Force of Membranes
| Compression Forces |
Membrane Plates • Accept centenary cables and pin connection hardware
Diagram 3.0 Tensile Force of Masts
• Tensile Stresses High tension force acting on the membrane to form the conical shape at the top and bottom ring, causing higher internal reaction forces, hence, higher distribution of internal stresses at that region. [ Diagram 4.0 ]
• Dead Load Cable
Steel Cable - High tensile strength of steel as an ideal structural element to span large distances.
Precipitation
Cables that hold the membrane and trusses are connected to the top of the masts to evenly dissipate the compressive forces. High compressive strength of the steel masts allow them to resist the compressive force.
• Components of Tensile Structure Stainless Steel - Most of the structure is made of stainless steel. The high strength and anti-corrosion properties allow the structure to have a longer life span.
High tensile strength of PTFE fabric allow it to resist environmental load and distribute the tensile stresses through its own form. The high points overcome the rain and snow acting downward, while the low points resist the uplift of wind.
Tensile Force
MATERIALS Teflon-Coated Fiberglass (PTFE) - It’s the most durable membrane used in tensile fabric structure. It is highly elastic, flexible and does not significantly expand or shrink under stress. It is immune to UV degradation and has long life-span, hence, suitable for projects located in extreme weather conditions.
| Membranes |
Base plate • connection to concrete foundation pillar
Weight of the membrane, bale rings, and trusses are supported by masts.
• Environmental Load Membrane • Forms the enclosure of the structure
Bale ring • Provide a link between the membrane and structural elements at the top bottom of conical shapes
Openings provided by the bale rings and trusses allow precipitations to drain off, reducing weight acting on the structure, and allow wind to pass through, reducing uplift. High tensile strength of the cable and membrane also help to overcome the environmental load.
High Distribution
Low Distribution
[ Diagram 4.0 ]
S K Y S O N G AT A S U C A M P U S | F T L D E S I G N E N G I N E E R I N G S T U D I O CONSTRUCTION DETAILS
OTHOGRAPHIC DRAWINGS Plan View Scale 1: 600
MODELING PROCESS
Detail I – Connection of Steel Cable to Banana Truss Scale 1:200
Steel Cable
Hinge Joint
01
Using satay stick to make the trusses structure. Trusses is use to connect with the fabric membranes.
03
White socks is used as the membrane of the tensile fabric structure. Following the plan view template, cut the exact same shape of membrane.
02
Eight “steel structures” are made into 4 A-Shaped frame to act as the masts.
04
Cutting two holes on each membrane and adding ring-shaped structure on it.
05
Glued all the four membranes and banana truss together. Place them on the plan view template to achieve the shape.
06
Using sewing method and glue to secure the membrane plates to the base plate.
06
White thread are used to act as the cable to hole the steel structure and membrane in place.
06
Pin Joint
A
A’ Banana Truss
Detail II– Membrane Plate
Scale 1:200
Edge Cable
Elevation Scale 1:600
Comer Plate
Spherical Washer Tie Bar
Thread Fitting in Sleeve
Bolted Joint
Detail III – Connection of Bale Ring to Mast Scale 1:200 Section A - A' Scale 1:600 Bale Ring Circular Hollow Mast
Conical Steel Structure
Hinge Joint
Steel Cable
Pint Joint
Model has completed.
REFERENCES • FabriTec Structures. (2018). ASU SkySong Innovation Center. Retrieved from PFEIFER FabriTec: https://fabritecstructures.com/portfolio/asu-skysong-innovationcenter/ • Padgett, M. (2009, February 25). Despite progress, Arizona falling behind other states in technology, report says. Retrieved from Arizona Notebook: http://arizonanotebook.com/page/18 • Structures, U. S. (Director). (2012). SkySong: the ASU Scottsdale Innovation Center by FabriTec Structures [Motion Picture].
BUILDING CONSTRUCTION II PROJECT 2 : UNDERSTANDING FORCES TUTOR . MOHAMED RIZAL MOHAMED
LOI CHI WUN NG ZIEN LOON CHEOK KAHYING AZEERAH MUBARAKH ALI
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