Ground motion characteristics of the Chi-Chi earthquake of 21 September 1999

Loh, Chin‐Hsiung; Lee, Zheng-Kuan; Wu, Tsu-Chiu; Peng, S.-Y

doi:10.1002/(sici)1096-9845(200006)29:6<867::aid-eqe943>3.0.co;2-e

Cited by 54 publications

(20 citation statements)

References 9 publications

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“…With T p = 0.9 s and p = 1.4 rad/s, ω p / p = 5, and according to the bottom plots of Figure , which are for slenderness α = 14°, the minimum overturning acceleration of a rocking frame with γ = 0.25 exceeds the value of a p ≈ 5 g × 0.24 = 1.2 g . This analysis shows that the free‐standing peristyles of ancient temples can survive acceleration pulses as long as 0.9 s and as intense as 1.2 g. Although this is a physically realizable pulse , it is an unlikely strong shaking for the seismicity of Greece that apparently never happened over the 2500 years of the lifespan of the temples shown in Figures and .…”

Section: Seismic Stability Of Ancient Columns Supporting Epistyles Anmentioning

confidence: 85%

Planar rocking response and stability analysis of an array of free‐standing columns capped with a freely supported rigid beam

Makris

Vassiliou

2012

Earthq Engng Struct Dyn

198

231

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SUMMARY This paper investigates the planar rocking response of an array of free‐standing columns capped with a freely supported rigid beam in an effort to explain the appreciable seismic stability of ancient free‐standing columns that support heavy epistyles together with the even heavier frieze atop. Following a variational formulation, the paper concludes to the remarkable result that the dynamic rocking response of an array of free‐standing columns capped with a rigid beam is identical to the rocking response of a single free‐standing column with the same slenderness yet with larger size, that is a more stable configuration. Most importantly, the study shows that the heavier the freely supported cap beam is (epistyles with frieze atop), the more stable is the rocking frame regardless of the rise of the center of gravity of the cap beam, concluding that top‐heavy rocking frames are more stable than when they are top light. This ‘counter intuitive’ finding renders rocking isolation a most attractive alternative for the seismic protection of bridges with tall piers, whereas its potential implementation shall remove several of the concerns associated with the seismic connections of prefabricated bridges. Copyright © 2012 John Wiley & Sons, Ltd.

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Section: Seismic Stability Of Ancient Columns Supporting Epistyles Anmentioning

confidence: 85%

Planar rocking response and stability analysis of an array of free‐standing columns capped with a freely supported rigid beam

Makris

Vassiliou

2012

Earthq Engng Struct Dyn

198

231

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“…These velocity waveforms were derived by integrating the accelerograms, shown in Fig. 2, by using a linear acceleration method in the time domain velocity pulse and pulse-like ground motions observed near surface of the faults can be considered to be the effect of the forward rupture directivity or the tectonic offset (e.g., Loh et al 2000;Mavroeidis and Papageorgiou 2003;Hisada and Bielak 2003;Baker 2007;Dreger et al 2011). The Kathmandu Valley is located at a very close distance (~10 km) from the rupture area, and large slip areas likely exist near the valley (Galetzka et al 2015).…”

Section: Ground Velocitiesmentioning

confidence: 99%

Strong ground motion in the Kathmandu Valley during the 2015 Gorkha, Nepal, earthquake

Takai

Shigefuji

Rajaure

et al. 2016

Earth Planets Space

127

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On 25 April 2015, a large earthquake of Mw 7.8 occurred along the Main Himalayan Thrust fault in central Nepal. It was caused by a collision of the Indian Plate beneath the Eurasian Plate. The epicenter was near the Gorkha region, 80 km northwest of Kathmandu, and the rupture propagated toward east from the epicentral region passing through the sediment-filled Kathmandu Valley. This event resulted in over 8000 fatalities, mostly in Kathmandu and the adjacent districts. We succeeded in observing strong ground motions at our four observation sites (one rock site and three sedimentary sites) in the Kathmandu Valley during this devastating earthquake. While the observed peak ground acceleration values were smaller than the predicted ones that were derived from the use of a ground motion prediction equation, the observed peak ground velocity values were slightly larger than the predicted ones. The ground velocities observed at the rock site (KTP) showed a simple velocity pulse, resulting in monotonic-step displacements associated with the permanent tectonic offset. The vertical ground velocities observed at the sedimentary sites had the same pulse motions that were observed at the rock site. In contrast, the horizontal ground velocities as well as accelerations observed at three sedimentary sites showed long duration with conspicuous long-period oscillations, due to the valley response. The horizontal valley response was characterized by large amplification (about 10) and prolonged oscillations. However, the predominant period and envelope shape of their oscillations differed from site to site, indicating a complicated basin structure. Finally, on the basis of the velocity response spectra, we show that the horizontal long-period oscillations on the sedimentary sites had enough destructive power to damage high-rise buildings with natural periods of 3 to 5 s.

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“…8(a), the first observation is the good agreement between observed strong-motion records and our predicted relationships, which includes an anelastic attenuation term up to a distance of 200 km for an event that is more than one unit over the magnitude range covered by the predictive model. However, the observed PGA values from the Taipei Basin, and the Ilan Basin, at distances between 50 and 80 km, are significantly higher than the rest of the data set (Loh et al 2000;Tsai & Huang 2000;Wen & Yeh 2001). Predictions are calculated through the RVT given the empirical attenuation parameter, source spectrum and its duration in time.…”

Section: Ground Motion Predictions Based On Point-source Model Smsimmentioning

confidence: 78%

Predictions of high-frequency ground-motion in Taiwan based on weak motion data

D’Amico¹,

Akinci²,

Malagnini³

2012

Geophysical Journal International

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SUMMARY Following a recent paper we use weak‐motion waveforms to calibrate a model for the prediction of earthquake‐induced ground‐motion in Taiwan, in the 0.25–5.0 Hz frequency range, valid up to Mw 7.6. The excitation/attenuation model is given in terms of frequency‐dependent seismic wave attenuation, Qs(f), geometrical spreading, g(r), a magnitude‐dependent stress parameters Δσ for the excitation terms, and a site term for each seismic station used in the study. A set of weak‐motion data was gathered from about 170 aftershocks of the Chi–Chi earthquake, Mw 7.6, of 1999 September 20, (17:47 UTC), recorded by 10 broad‐band seismic stations. The moment magnitudes of the registered aftershocks ranged from Mw 3.0 to 6.5, and the hypocentral distances from a few kilometres to about 250 km. A frequency‐dependent crustal quality factor, Q(f) = 350f0.32, was obtained, to be coupled with the geometrical spreading function Earthquake‐related excitation spectra were calibrated over our empirical results by using a magnitude‐dependent Brune model with a stress drop value of Δσ= 8.0 ± 1.0 MPa for the largest event of Mw 6.5 in our data set and with a near surface attenuation parameter of κ= 0.05 s. Results on region‐specific crustal attenuation and source scaling were used to generate stochastic simulations both for point‐source and extended‐fault ruptures through the computer codes: Stochastic Model SIMulation, SMSIM and Extended‐Fault Model Simulation, EXSIM. The absolute peak ground accelerations (PGA), peak ground velocities (PGV) and 5 per cent‐damped Spectral Accelerations (SA) at three different frequencies, 0.33 Hz, 1.0 Hz and 3.0 Hz for several magnitudes and distance ranges were predicted at large magnitudes, well beyond magnitude Mw 6.5, the upper limit for the events of our weak‐motion data set. The performance of the stochastic model was then tested against the strong‐motion data recorded during the Mw 7.6 Chi–Chi earthquake, and against several other empirical ground‐motion models.

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Ground motion characteristics of the Chi-Chi earthquake of 21 September 1999

Cited by 54 publications

References 9 publications

Planar rocking response and stability analysis of an array of free‐standing columns capped with a freely supported rigid beam

Planar rocking response and stability analysis of an array of free‐standing columns capped with a freely supported rigid beam

Strong ground motion in the Kathmandu Valley during the 2015 Gorkha, Nepal, earthquake

Predictions of high-frequency ground-motion in Taiwan based on weak motion data

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