COLLAPSE OF THE TUNGSHING BUILDING DURING THE 1999 CHI-CHI EARTHQUAKE IN TAIWAN

摘要

On September 21, 1999, 1:47 a.m. local time, a major earthquake (M_w=7.6) struck the island of Taiwan near the city of Chi-Chi in Nantou County. The capital city of Taipei, located 150 km north of the epicenter, faired well during the Chi-Chi earthquake. Overall, the ground shaking intensity in the city was modest (M_w=4.0). It was reported that some people did not feel, or barely felt, the earthquake in Taipei. Despite the modest levels of ground shaking intensity in Taipei, the 12-story Tungshing building, located in the Sungshan area of Taipei collapsed unexpectedly. The fundamental objective of this research is to determine the cause of collapse to the Tungshing building during the 1999 Chi-Chi earthquake in Taiwan. Based on a review of the construction documents and the results of nonlinear time history analyses, it was found that construction difficulties associated with congestion of reinforcement may have created weaknesses in the structural system. Poor ductile seismic detailing by the designer resulted in columns that lacked energy dissipation capacity and were susceptible to brittle shear failure. Inadequate anchorage of the bottom beam bars at the exterior columns resulted in the beams tearing away from the columns, severely damaging the columns, and probably triggering a progressive collapse mechanism.