The Change of the Dynamic Characteristics Using Microtremor

Abstract eng:
Considering the geotectonic environment and the historical importance, it is necessary to investigate the dynamic characteristics of the historical constructions in the city for rational and effective countermeasures against earthquake disasters. Since autumn 1998, microtremor measurements had been started to investigate the dynamic characteristics of several structures in Istanbul. In 17th August 1999 the Kocaeli Earthquake (Mw7.6, maximum PGA for rock site in Istanbul was 41 Gal) occurred and caused severe damage in the epicentral area. Microtremor measurements were conducted for few structures including historical monuments such as Suleymaniye mosque, Hagia Sophia museum, Sehzade mosque, and a newly constructed 14 stories office building, before the earthquake. In order to assess the earthquake’s aftermath on the measured structures in Istanbul, microtremor measurement was again conducted. The result of the measurement before and after the earthquake shows the change of natural frequencies decreasing after the earthquake up to about 8.9% for Hagia Sophia Museum. The avKb value, averaged Kb value was proposed by Nakamura et al. (2000) as vulnerability index for buildings. Because the averaged drift angle of the buildings can be estimated by multiplying the avKb value and the maximum input earthquake acceleration, the avKb value was proposed to assess the possibility of building damage. The avKb values before the Kocaeli earthquake are corresponds to the change of natural frequencies. Thus, it is expected that the danger of a structure can be assessed by the avKb in advance.

• Export as: BibTeX | MARC | MARCXML | DC | EndNote | NLM | RefWorks
• Add to your basket