Approximate method of estimating seismic performance of high‐rise buildings with oil‐dampers

Abstract

Summary When subjected to long‐period ground motions, many existing high‐rise buildings constructed on plains with soft, deep sediment layers experience severe lateral deflection, caused by the resonance between the long‐period natural frequency of the building and the long‐period ground motions, even if they are far from the epicenter. This was the case for a number of buildings in Tokyo, Nagoya, and Osaka affected by the ground motions produced by the 2011 off the Pacific coast of Tohoku earthquake in Japan. Oil‐dampers are commonly used to improve the seismic performance of existing high‐rise buildings subjected to long‐period ground motion. This paper proposes a simple but accurate analytical method of predicting the seismic performance of high‐rise buildings retrofitted with oil‐dampers installed inside and/or outside of the frames. The method extends the authors' previous one‐dimensional theory to a more general method that is applicable to buildings with internal and external oil‐dampers installed in an arbitrary story. The accuracy of the proposed method is demonstrated through numerical calculations using a model of a high‐rise building with and without internal and external oil‐dampers. The proposed method is effective in the preliminary stages of improving the seismic performance of high‐rise buildings.

Identification of Far‐Field Long‐Period Ground Motions Using Phase Derivatives

“…It is deemed that effects of long-period ground motions during megaearthquakes could not be ignored even if epicenter distances exceed 500 km [30]. In this regard, it is noteworthy that such long-period ground motions are not often incorporated into the design spectrum for high-rise buildings [31] because engineering designs are driven by the expected magnitude of the earthquake and the distance to near faults. erefore, it is recommended that the influence of longperiod motions triggered by large faults on long-period structures at distant sedimentary sites should be taken into serious consideration.…”

Vulnerability assessment of a high‐rise building subjected to mainshock–aftershock sequences

“…The results and conclusions for low‐ to medium‐rise buildings cannot be directly applied to high‐rise buildings. [ 22–25 ] Besides, the earthquake damage in high‐rise buildings would lead to more fatalities and economic losses compared with lower buildings, and it is more unfavorable to post‐disaster relief and reconstruction. Further, high‐rise buildings account for an important part of metropolises, and their seismic performance has significant impact on the seismic resilience of cities.…”