The tensile structure designed for ASU provides a shaded courtyard for social interaction. The 50,000 sq ft structure is made of PTFE glass fabric stretched between steel columns and cables. Tension forces from the cables are transferred through the columns into the ground for stability, while compression forces are resisted by the steel A-frame columns. The flexible PTFE fabric and cable connections allow the structure to withstand environmental loads like wind and rain.

1. Scottsdale, AZ, USA
FTL in collaboration with Pei Cobb Freed & Partners (Architect for the Campus
Buildings) designed the sculptural tensile structure as a center piece for the
overall development of ASU, providing a shaded center courtyard with 4 plazas
for cafes, restaurants and social interaction. It serves as a landmark structure
in the area to attract visitors. The PTFE glass fabric structure is approximately
50,000 sq ft of area and opened in May 2009.
FORCES & LOAD DISTRIBUTION
MATERIALITY
Teflon-coated fiberglass (PTFE)
Its durability and tolerance against extreme weather conditions enhances its
mechanical strength and allows maximum flexibility for curvy structures.
steel columns and cables
Galvanized steelA-frame columns acting as masts can withstand the tension
forces through the connection with steel cables.
TENSION FORCES
CABLES
Tension forces from the cables are transferred from
the top to the base in a wide spread direction. This
ensures a larger base surface area for better stability.
COMPRESSION FORCES
Steel A-frames (masts) transfer load from the
top to the ground.
DEAD LOAD
The weight of the membrane, bale rings and banana
trusses are transported onto the ground through the
A-frame columns.
environmental LOAD
The whole structure can withstand the rain with the
integration of drainage in the bale rings, preventing
ponding of water in the fabric.
Wind load is also tackled with the strong connections
of the fabric, where it can withstand 650 pounds of
force per square inch.
MODELLING PROCESS
The initial model shows the exploration of materials and
technique of construction. The fabric used is unsuitable as it
lacks flexibility while the steel wire ‘banana’ trusses shows
imperfection in workmanship.
Stretchable fabric sewn onto banana trusses
and steel framing to ensure it is intact and
maintain its shape.
Improvised model with A-frame column
and base support (cork), banana trusses
(steel wire inserted into plastic tubes) and
framing of membrane structure.
1 2
3
fabric
Stretchable PTFE membrane withstands tension
with the support of cables, banana trusses and bale
rings, which forms a series of conical shapes.
The overall tension forces acting on the structure is well spread with an equal
amount of steel cable anchoring on all four sides of the membrane.
Pre-fabricated steel banana trusses
are hung on the A-frame columns
and act as connections of 4 pieces
of PTFE membranes.
After attaching rings to the fabric, the structure is
pulled into a pair of conical shapes with strings. It is
then further tied into position.
Fabricstresses
Maximum tension forces acting on the fabric
are on the top and bottom rings, which shapes
the conical structure.
WIND
Thin catenary cables inserted into fabric at the
sides to maintain the curvature of the
membrane structure.
ASU SKYSONG
TENSILE
STRUCTURE
4
TENSION FORCES
COMPRESSION FORCES
SABD | Building Construction II | BLD 60703 | Project 2 Understanding Forces in Building Construction | Mr Edwin | Cherilyn Chia 0321986 | Lim Woo Leon 0322180 | Shreya Maria Wilson 0322173
Tension Intensity
Low TensionHigh Tension
ASU SKYSONG
innovation centre
Concrete posts are built. A-frame columns and
pre-fabricated ‘Banana’ trusses are constructed and
supported by temporary cables.
After placing the bale rings in place with the support of
cables, the customized PTFE membrane is connected to
the top supporting cables and pulled upwards, forming its
conical shape.
The PTFE membranes are installed in-place piece by
piece with the sides joined to the Banana trusses, forming
a full symmetrical structure.
STRUCTURAL ANALYSIS
FLAT TO CURVE
PTFE membrane is cut into quarters of circular shape and
pulled into conical shapes with the bale ring and steel
cables.
STEEL CABLE ANCHORING
The cables are anchored to the top of the A-frame and
pulled to the banana structures and membrane to hang the
elements and then pulled to the ground to maintain their
positions.
CONSTRUCTION PROCESS
BALE RING SUPPORT
Bale rings positioned at the top and bottom of each pair of
A-frame columns allows the membrane to be tied into a
series of conical shapes.
C:UsersShreyaDesktopeditsASU002_0.png