Back Issues 11-20

INFLUENCE OF SHEAR BANDING ON BUILDING SAFETY AFTER URBAN RENEWAL

Tse-Shan Hsu

Professor, Feng-Chia University, and

President, Institute of Mitigation for Earthquake Shear Banding Disasters, Taiwan

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Zong-Lin Wu 

Assistant Professor, National Chin-Yi University of Technology, Taiwan

Yu-Chien Wu

Director, Institute of Mitigation for Earthquake Shear Banding Disasters, Taiwan

Tsai-Fu Chuang

Associate Professors, Feng-Chia University, Taiwan

Abstract

This study is based on the rebuilding of a four-floor building into a twenty-story building as part of a Taipei urban renewal project, which provided the opportunity for the landlords to obtain enormous benefits because of the high price of land in Taipei. This is also an example of the city government’s active promotion of urban renewal plans to improve the city's appearance. Based on this case study and in order to help develop appropriate urban renewal plans, the authors of this paper present the following four conclusions: (1) Taipei has shear-band displaced landform features and the shear banding effect keeps the onsite low-plastic silt alluvium in a soft state; (2) the static and seismic ultimate bearing capacities of building foundations are seriously overestimated due to improper assumptions made in the derivation of the relevant formulas; (3) the old four-floor building would have remained safe during a tectonic earthquake; however, the new twenty-story building does not remain safe during a tectonic earthquake; and (4) landlords will benefit greatly from urban renewal but only if their buildings remain safe after reconstruction. In this case study, the new twenty-story building was found to be unsafe during a tectonic earthquake, and the landlord could therefore risk heavy losses. Therefore, the authors suggest that before a large number of urban renewal plans are promoted in Taipei, the seismic design codes for buildings should be revised so that the static and seismic ultimate bearing capacities of the proposed building foundations can be correctly calculated. This is the only way to ensure that buildings complying with seismic design specifications remain safe during tectonic earthquakes.

Keywords: urban renewal, shear banding, bearing capacity, tectonic earthquake, strain softening.