Back Issues 11-20

MAJOR CAUSE OF FALL FAILURE OF MARKET BUILDINGS DURING TECTONIC EARTHQUAKES

Tse-Shan Hsu

President, Institute of Mitigation for Earthquake Shear Banding Disasters

Professor, Feng-Chia University, Taiwan, R.O.C., This email address is being protected from spambots. You need JavaScript enabled to view it.

Yu-Chien Wu

Ph.D. Students, Ph.D. Program for Infrastructure Planning and Engineering, 

Feng-Chia University, Taiwan, R.O.C.

Zong-Lin Wu  

Assistant Professor, National Chin-Yi University of Technology, Taiwan, R.O.C

Ching-Chang Lin, Da-Jie Lin

Associate Professors, Feng-Chia University, Taiwan, R.O.C.

Abstract

Since the seismic design code of buildings was promulgated for the first time in Taiwan in 1974, the ground vibration fortification level has been continuously improved after each severe earthquake. However, the failure of market buildings has not been prevented. In view of this, the authors of this paper explore the fall failure of the Dazhi Market building in Tainan, Taiwan, as a case study. It is revealed that ground vibration accounts for less than 10% of the total seismic energy dissipation associated with an earthquake, so that structural seismic reinforcement of market buildings against ground vibration accounts for less than 10% of the effectiveness of protection. On the other hand, the major cause of fall failure of market buildings situated on alluvial sandy silt layers above shear banding zones is identified as plastic strain softening, which causes the earthquake induced subsidence of the building foundation to occur suddenly. All columns connected to the foundation collapse because of the influence of excessive impact forces. Based on these findings, the authors suggest that market buildings should be strategically situated to avoid shear banding zones. Furthermore, the initial version of the seismic design code for fortification of buildings specifically against ground vibration, is inadequate. Only through consideration of the effect of shear bands can the fall failure of market buildings and the unnecessary expenditure on ground vibration fortification in non-shear banding zones be prevented.

Keywords: market building, tectonic earthquake, shear banding, ground vibration, 

strain softening, fall failure.