BANGKOK MONORAIL
Bangkok is the capital and biggest city of Thailand, with a population of over 8 million people.
Two Monorail lines are currently under construction: the Pink Line of 34,5 km and the Yellow Line of 30,4 km.
The structure mainly consists of a repetition of 3 or 4 continuous spans of 30 m supported by columns having typical height 15,5 m.
The beams are connected to the piers in the intermediate spans by fixed bearings and in correspondence with the expansion joints by one fixed bearing and in the opposite side by one movable bearing.
The train is supported by the beam on top and laterally in the so called straddle configuration. In that way the beam and consequently the bearings are subjected not only to the vertical load but also to quite important transversal horizontal actions and moments due to the centrifugal effects and the snaking of the trains.
Product
HIFLOW
Year
2020
Country
South Korea
Owner
Mass Rapid Transit Authority of Thailand (MRTA).
Designer
SINO-THAI
Technicalities
The basic design idea was to use two spherical bearings mounted on the same structure.
The transversal moment is resisted by tension of one bearing and compression of the other, giving as resultant the required moment. The anchors are suitably shaped to transfer tension forces to the concrete. Sliding materials are the most critical components of the spherical bearings. The material utilized for the bearings of Bangkok Monorail is based on a modified PTFE and we applied to it the commercial name HI-3.
The basic performances of HI-3 are summarized in the following table and put in comparison with the performances of PTFE according to EN 1337.2 and with an alternative material UHMWPE
PROPERTY | HI-3 | PTFE | UHMWPE |
Compressive strength | 180 MPa | 90 MPa | 180 MPa |
Heat resist. (long term) | 90°C | 48°C | 48°C |
Heat resist. (short term) | 120°C | 48°C | 80°C |
Wear resistance | 50,000 m | 10,000 m | 50,000 m |
Static friction | 3% | 3% | 3% |
The testing program on complete bearings has been very severe
The prototype tests had the aim to verify the resistance of the bearings and their connection to the concrete structure, both for static and fatigue loading conditions.
To perform the tests, it has been used full scale real bearings and a suitable length of the adjacent concrete structures, incorporating the real reinforcement.
The tests have been performed at Eucentre, independent laboratory of the Pavia University.
For the fatigue tests the vertical load has been applied for 2 million cycles at a frequency of 3 Hz on the first bearing with total duration of the test of 185 hours.
The test on the second bearing has been performed at the frequency of 5 Hz with a duration of 112 hours
Production
