Taipei 101 is designed to withstand the typhoon winds and earthquake tremors common in its area of the Asia-Pacific. Planners aimed for a structure that could withstand gale winds of 60 m/s (197 ft/s, 216 km/h or 134 mph) and the strongest earthquakes likely to occur in a 2,500 year cycle.[23]
Skyscrapers must be flexible in strong winds yet remain rigid enough to prevent large sideways movement. Flexibility prevents structural damage while resistance ensures comfort for the occupants and protection of glass, curtain walls and other features. Most designs achieve the necessary strength by enlarging critical structural elements such as bracing. The height of Taipei 101 combined with the demands of its environment called for additional innovations. The design achieves both strength and flexibility for the tower through the use of high-performance steel construction. Thirty-six columns support Taipei 101, including eight "mega-columns" packed with 10,000 psi (69 MPa) concrete.[24] Every eight floors, outrigger trusses connect the columns in the building's core to those on the exterior.[25]
These features combine with the solidity of its foundation to make Taipei 101 one of the most stable buildings ever constructed. The foundation is reinforced by 380 piles driven 80 m (262 ft) into the ground, extending as far as 30 m (98 ft) into the bedrock. Each pile is 1.5 m (5 ft) in diameter and can bear a load of 1,000–1,320 tonnes (1,100–1,460 short tons).[24] The stability of the design became evident during construction when, on 31 March 2002, a 6.8-magnitude earthquake rocked Taipei. The tremor was strong enough to topple two construction cranes from the 56th floor, the highest floor at the time. Five people died in the accident, but an inspection showed no structural damage to the building, and construction soon resumed.[25]