CHANGES IN NATURAL PERIOD OF BUILDINGS CAUSED BY PILE FAILURE DURING THE 1995 HYOGOKEN-NANBU EARTHQUAKE

Abstract

This paper mainly discusses changes in the natural period of buildings before and after pile failure based on microtremor measurements. Many underground piles were significantly damaged during the 1995 Hyogoken- Nanbu earthquake. The results of analysis indicate that the natural period of the buildings which suffered from pile damage, is longer than that of the buildings without pile damage. However, after the reconstruction of piles, the natural period tends to be shorter than that of buildings with damaged piles, and is similar to that of buildings with undamaged piles. These facts show that the damage to the pile foundation can be evaluated from the natural period of buildings based on microtremor mesurements.