In 2013 Flow Engineering was awarded the contact for the calculation, design, delivery and installation of three TMD systems for the world’s highest flagpole until 26 December 2021. The pole located in Jeddah – Saudi Arabia is 170 meters high and weighs approximately 500.000 kg. The pole is tapered starting at the base with a diameter of 4.1 meter ending in the top with a diameter of 2 meter. The flag weighs 515kg and is 60 meters in length and 30 meters wide. Three tuned mass damper systems are installed in the pole with a total weight of 11.000kg. The first two dampers are installed in the top section of the pole and the third damper is installed at a height of 125 meters. Together the three tuned mass dampers provide sufficient damping to prevent large oscillations of the pole caused by vortex shedding in its first second and third natural frequencies.
A temporary TMD was designed and used during the construction of the flagpole. The possibility existed that the pole would vibrate (due to the vortex shedding) before the sections with the TMD could be installed. The temporary TMD was installed in section 5 of the flagpole to add damping to the flagpole during the erection of the pole. After section 6 was installed on section 5 the temporary TMD is lifted from section 5 and reinstalled in section 6. This procedure was repeated all to way to the top section after which the temporary TMD was lifted out the flagpole.