Response of a tall building far from the epicenter of the 11 March 2011 M 9.0 Great East Japan earthquake and aftershocks

Abstract

SUMMARYThe 11 March 2011 M 9.0 Great East Japan earthquake generated significant long-duration shaking that propagated hundreds of kilometers from the epicenter and affected urban areas throughout much of Honshu. Recorded responses of a tall building at 770 km from the epicenter of the mainshock and other related or unrelated events show how structures sensitive to long-period motions can be affected by distant sources. Even when the largest peak input motions to the building is about 3% g, the strong-shaking duration was about 140 s. The 300-to 1000-s prolonged responses of the building are primarily due to a combination of site resonance (e.g. structural fundamental frequency~0.15 Hz and site frequency~0.13-0.17 Hz) and low damping (~1-2%) of the structure. Response modification technologies can improve the response of the building during future earthquakes. The need-to-consider risks to such built environments from distant sources are emphasized.

Seismic hazard in Buenos Aires, Argentina: A preliminary study on the effects of long‐distance earthquakes on tall buildings

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“…These studies emphasize the need to consider risk from distant sources in built environments and show that the prolonged response of buildings due to distant earthquakes is a consequence of the effects of traveling long-period motions and a combination of site resonance and low damping of the structures. [5][6][7] This short communication studies the ground motions recorded in Buenos Aires during the 2015 Illapel earthquake and 13 aftershocks, characterizing amplitude and frequency content parameters. The response of tall buildings during the main event is investigated and compared with acceptable values for wind-induced vibrations and nonstructural damage thresholds.…”

Optimal Placement of Hysteretic Dampers via Adaptive Sensitivity-Smoothing Algorithm

“…In order to overcome such difficulty, a new optimization method including a variable adaptive step length for sensitivity smoothing is proposed. Although a constraint on accumulated plastic deformation ratio is sometimes required in hysteretic dampers for long-duration earthquake ground motions [3,4,7,36], this is not taken into account here because of a simple, essential presentation of a new optimization procedure. Figure 7 shows the maximum interstory drift and the variation of the maximum interstory drift to the change (decrease) of damper stiffness in the story marked by circle.…”

Structural Identification of an 18-Story RC Building in Nepal Using Post-Earthquake Ambient Vibration and Lidar Data

“…The damping estimate mean values are reasonable for a tall building except for that of mode 1 (Satake et al, 2003;Harris et al, 2015). The mean values of identified damping ratio for the first mode is 5.1% for Setup 1 and 7.5% for Setup 2, that are too large for a tall building (Arakawa and Yamamoto, 2004;Çelebi et al, 2014). This can be caused by the fact that three closely spaced modes with natural frequencies around 0.6 Hz are identified as one mode with an inflated damping ratio to account for the three peaks.…”