Page 24 - Wire Rope News & Sling Technology - December 2018
P. 24

continued from page 22
         small load  run very fast than a huge   The Singapore Sports Hub Moving Roof: How Does it Work?
         load run at a very low speed. Each roof   If you flew over the Sport Hub when the roof was open, you’d see two curved
         panel would weigh 1,250 tons, but it   panels flanking a huge opening with five trusses arching across it. Each panel,
         would travel at a velocity of just 40mm   200m x 50m, 10,000m , and 1,250T, travels across five runway trusses via bo-
         per second. That’s very slow.”       gies – four bogies on each truss, travelling on tracks.
           Still, there were concerns that could   For safety, a storm brake is connected to the rear bogies of each truss. In
         contribute to sleepless nights – like the   case of a windstorm, for instance, the brake will clamp the roof panel onto
         dire consequences of even one miscal-  the track. The brakes also have the same function as a track rope brake on
         culation. “If  you made  one mistake,   an aerial ropeway - in case of lack of tension or over-tension on any rope, or
         you couldn’t correct it because once   overspeed of any panel, the storm brake will halt the roof.
         the whole  system was installed, you   To drive the roof panels, winches are located on the rear side of each pan-
         couldn’t dismantle it. You would have   el. Driving lines are located on runway trusses RWT2 and RWT4, with four
         to stand on the roof. And at that point   wire ropes and winches per line. Each winch is fitted with a 50mm high per-
         the roof would no longer be accessible.”  formance wire rope (eight strands, plastic infill, compacted outer and inner
           Safety was a major concern. The    strands.) The driving force is 450T per roof panel. The distribution of the load
         roof  was designed to  operate during   among the wire ropes of the same driving line is very important. To see the
         events, which meant that it would be   video, go to
         moving above as many as 50,000 peo-
         ple. The safety requirements would
         be the same as those used for trans-                                                  RWT5
         porting people. A safety brake was in-
         stalled, which would lock the roof in                                            RWT4
         place should a rope fail.                                                       RWT3
           “There  were  different options for
         where to put the hoisting units, but the                                     RWT2
         architects wanted it on the roof. For us,
         from a technical point of view, it was                                      RWT1
         more complex. But we found solutions.
         For  this  project,  we  were  involved in
         the early stages of the design, so it                                                  continued on page 26
         wasn’t a problem.”
           To  add to the attractiveness of  the
         structure, the architects wanted almost
         nothing visible to the spectators when
         they looked up at the open roof. So, the   “Basically, the 1,250-ton roof is roll-  “Just to give you an idea, when we
         supporting structure of the moving roof   ing on tracks that follow the line of the   change  the  configuration  of  the  stadi-
         would need to be very light.       fixed roof. And depending on the wind   um, that means a vertical lift of more
           “Furthermore, this structure is curved   and the weight, they can move up or   than 5,000 ton and horizontal shift of
         in two directions. The biggest challenge   down, and also laterally, up to half a   more than 10,000 ton.
         was the design of a mechanism able   meter of misalignment.             (To understand how it works, see vid-
         to comply with these specificities. (See   “And it is thanks to the specific slid-  eo link at
         sidebar,  “The  Singapore  Sports  Hub   ing bearings installed on the bogies   “This is the machine that moves the
         Moving Roof: How Does it Work?”)   that we are able to move the roof in a   concourse  platforms,” explains Teissi-
           “The hoisting system for moving the   straight direction with a track going   er. “It uses Serapid chain. So we named
         roof  must  accommodate the  shape of   sideways. And this is the first time for   this the Serapid machine.”
         the  structure,  the  weight  of  the  roof   such a large roof. This is the biggest   Pointing  to  a  diagram,  he  explains,
         and the wind load.                 that has ever been done.”          “The machine transfers the concourse
           “That means that the bogie wheels                                   platform to the upper or lower position.
         are not running  on the same radius,   Intrepid Serapid moves stadium   It has to be safe, so we designed a lock-
         thus not at the same velocity. So, we   seats                         ing system so that once the platform is
         had to make provisions  for  that. We   While Teissier’s company worked on   in position it will be naturally locked and
         designed  a  very  specific  control  unit   the intricacies of the roof system above,   thus will never fall down. Here, on each
         for the winches  because we had six-  they were also tasked with solving the   platform, is a set of four locking arms.”
         teen winches on the roof – (two moving   problem of how to move the stadium   For cost efficiency, the driving unit
         panels, two groups of four winches on   seats below. The Sports Hub holds foot-  for the locking arms is located on the
         each), and the skew of the moving roof   ball, cricket and athletic events. The   Serapid machine. So only one unit is
         had to be limited in order not to dam-  lower tiers would need to be reconfig-  required for the 49 platforms. Once
         age its structure. From the beginning   ured for each.                the process begins, workers have 48
         we had to make provisions so that we   “We were on site,” says Teissier,   hours  to  change  the  configuration  of
         could adjust them on site.”        “and they asked us if we could do the   the stadium. They work 12 hour shifts
           The  solution  was  to  create  what   project because we had diverse experi-  for four days straight.
         Teissier calls a “flexible” system. The   ence. And I said, ‘Of course we can.’”   A monstrous machine - 10m x 8m x
         roof runs on beams with tracks, sup-  The system first shifts the tiers like a   (2m retracted/12m extended), 55T - the
         ported by huge bogies, and is powered   waterfall and then hoists the concourse   Serapid skids along the floor of the sta-
         by wire ropes spooled onto winches.   platforms (See photo on page 22).                continued on page 26

         24     Wire Rope News & Sling Technology   December 2018
   19   20   21   22   23   24   25   26   27   28   29