r - The Hong Kong Polytechnic University

STADIUM ROOF BRIEF
Jaber Al-Ahmad International Stadium adopted a single layer saddle radial-ring cable-net covered with
membranes. The upper edge of the stand undulates greatly due to optimization of the viewing distance and at the
same time provide requisite for a saddle-shaped double-curved surface. The plan is almost circular with main
axes 280mx260m. The roof opening over the field is formed by the cable tension ring, which has an affinity to
the outer compression ring. By contrast, the oval membrane roof is aligned to the spectator stands [2].
a) photo in construction b) single layer cable net roof
Figure.3 Jaber Al-Ahmad International Stadium
As shown in Figure.3, the overall plan is 282m 256m elliptic with openning 109m 119m elliptic. The roof
consists of 55 radial cables (RAC) and 10 ring cables (RIC), a PTFE fabric tensegrity module covers a cable
gird with four lower stabilized cables and a flying strut, over three hundred modules with various sizes cover
whole roof. This looks like white wavelet over the sand [3].
As the main structural performance of cable net concerned, only cable nets was thus taken into the analysis
model without outer undulation compression ring, huge circular hollow section steel beam, and coverage of
membrane. They are assumed boundary and dead load. Table.1 shows the cable size. The modulus set 190GPa.
Location
Table.1 The size of cables
RIC (Numbering from opening to outer ring)
RAC
1 2 3 4 5~10
size 8-(5×187) 5×223 5×211 5×199 5×187 5×199
PRE-STRESS AND STATIC PERFORMANCE
Pre-stress has two functions to the flexible cable nets, the first is to form the shape, the second is to develop and
maintain stiffness. Rational geometry of negative gauss curvature and introduction of pre-stress are the basic
requisite to achieve high performance of the cable net roof.
Figue.4 shows cable net layout, the size gives in Table.1. The initial location of the cable net was set according
to architect design. The initial pre-stress were optimized with respect to the deflection requirement of centre
tension ring. The cable net can be assumed all un-compression pre-stressed link assembly, which is proved
one static redundancy and one kinematic mechanism. Only one cable set specific pre-stress, the tensions of other
cables can be easily calculated from the called force-finding method which is based on the linear adjustment
theory and force density method. It was a try-on process and finally the optimized pre-stress were got in
engineering sense. Table.2 gives the initial pre-stress of the cable nets.
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