When a magnitude 7.2 earthquake hit Taiwan on Apr. 3 morning, several buildings in its eastern county of Hualien, located near the earthquake’s epicentre, collapsed.

In contrast, the island's tallest building — Taipei 101 — remained standing, even though the earthquake was the strongest one that Taiwan experienced in 25 years.

One special design that helped reduce the swinging of the 508m-tall skyscraper was a yellow wind-damping ball, known as the “Tuned Mass Damper” (TMD).

Details of TMD

Consisting of 41 layers of 12.5cm solid steel plating, the TMD has a diameter of approximately 5.5m and weighs 660,000kg, according to Taipei 101's website.

The damper is suspended between several floors on the top of Taipei 101 by 92 steel cables.

Each cable, which consists of more than 2,000 independent steel wires, has a diameter of 8.9cm and a length of 42m.

Under the TMD are eight large hydraulic viscous wind dampers that further enhance its stability by absorbing sways.

The TMD also comes with a bumper ring that is connected horizontally to the eight hydraulic dampers, effectively limiting the ball's swing to 1.5m during earthquakes and typhoons.

How it works

When Taipei 101 starts swinging during earthquakes, the TMD will "pull" the skyscraper back with the steel cables as a result of inertia.

The damper will also help to cancel out Taipei 101's swinging by moving in its opposite direction.

Concurrently, the swinging of TMD will stretch and compress the hydraulic dampers under it, causing them to generate friction that will gradually stop the skyscraper from swinging.

Here’s how the TMD went into action when typhoon Soudelor, the strongest tropical cyclone of the 2015 Pacific typhoon season, struck Taiwan.

According to Taipei 101, the TMD can curtail the skyscraper’s movement by up to 40 per cent.

Also an 'aesthetic attraction'

Besides its functional use, the TMD is also open to the public for viewing as an “aesthetic attraction”.

Those who are keen to check out the damper system can visit Taipei 101's observation deck on the 89th floor.

A general adult ticket, which allows ticket holders to visit floors 88, 89, and 91, costs 600 New Taiwan Dollars (S$25.20) and can be booked here.

Top images via Mr. 藍莓左輪LEoN/Xiaohongshu & 台北101/Facebook