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Characteristics of frequency content of near-fault ground motions during the Chi-Chi earthquake
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作者 徐龙军 谢礼立 《Acta Seismologica Sinica(English Edition)》 EI CSCD 2005年第6期707-716,750,共11页
The frequency content of earthquake ground motion is very important because it affects the dynamic response of structural systems. In the paper, we use five scalar parameters (the response spectral predominant period ... The frequency content of earthquake ground motion is very important because it affects the dynamic response of structural systems. In the paper, we use five scalar parameters (the response spectral predominant period Tp, smoothed spectral predominant period To, Fourier amplitude spectral mean period Tm, equivalent pulse period Tv, and the pseudo-velocity spectral predominant period Tpv) reflecting the characteristics of frequency content of strong ground motion to examine the near-fault three-component motions during the 1999 Chi-Chi earthquake. The result indicates that the frequency content of near-fault motions at the Hanging wall is less than that at the foot wall; Tp shows a smaller value than that of To and Tm and it emerges a reverse relation of three-component motions as compared with that of To and Tm; Tv and Tpv of the near-fault motions at the north end of the rupture display a similar trend to that generated by the rupture directivity effect of strike-slip faulting. We therefore conclude that these observations are useful in the formulation of near-fault design spectra for seismic codes and in zoning studies in seismic risk. 展开更多
关键词 frequency content directivity effect hanging-wall effect Chi-Chi earthquake
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Fractal characterization and frequency properties of near-fault ground motions 被引量:2
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作者 Yang Dixiong Zhang Changgeng 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2013年第4期503-518,共16页
This study explores the irregularity and complexity of strong earthquake ground motions from the perspective of fractal geometry, and constructs a relation with the frequency content of the ground motions. The box-cou... This study explores the irregularity and complexity of strong earthquake ground motions from the perspective of fractal geometry, and constructs a relation with the frequency content of the ground motions. The box-counting fractal dimensions and five representative period parameters of near-fault ground motions from the Chi-Chi and Northridge earthquakes are calculated and compared. Numerical results indicate that the acceleration and velocity time histories of ground motions present the statistical fractal property, and the dominant pulses of near-fault ground motions have a significant influence on their box dimensions and periods. Further, the average box dimension of near-fault impulsive ground motions is smaller, and their irregular degree of wave forms is lower. Moreover, the box dimensions of ground motions reflect their frequency properties to a large extent, and can be regarded as an alternative indicator to represent their frequency content. Finally, the box dimension D of the acceleration histories shows a considerably negative correlation with the mean period T. Meanwhile, the box dimension of the velocity histories Dye is negatively correlated with the characteristic period T and improved characteristic period Tgi. 展开更多
关键词 near-fault ground motions fractal property box-counting dimension frequency content indicators correlation analysis
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Seismic fragility of structures isolated by single concave sliding devices for different soil conditions 被引量:5
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作者 P.Castaldo G.Amendola M.Ripani 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2018年第4期869-891,共23页
This study deals with the seismic fragility of elastic structural systems equipped with single concave sliding(friction pendulum system(FPS)) isolators considering different soil conditions. The behavior of these ... This study deals with the seismic fragility of elastic structural systems equipped with single concave sliding(friction pendulum system(FPS)) isolators considering different soil conditions. The behavior of these systems is analyzed by employing a two-degree-of-freedom model, whereas the FPS response is described by means of a velocity-dependent model. The uncertainty in the seismic inputs is taken into account by considering artificial seismic excitations modelled as timemodulated filtered Gaussian white noise random processes of different intensity within the power spectral density method. In particular, the filter parameters, which control the frequency content of the random excitations, are calibrated to describe stiff, medium and soft soil conditions. The sliding friction coefficient at large velocity is also considered as a random variable modelled through a uniform probability density function. Incremental dynamic analyses are developed in order to evaluate the probabilities of exceeding different limit states related to both the reinforced concrete(RC) superstructure and isolation level, defining the seismic fragility curves within an extensive parametric study carried out for different structural system properties and soil conditions. The abovementioned seismic fragility curves are useful to evaluate the seismic reliability of base-isolated elastic systems equipped with FPS and located in any site for any soil condition. 展开更多
关键词 friction pendulum devices seismic isolation soil condition frequency content seismic fragility
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Effects of hanging wall and footwall on demand of structural input energy during the 2008 Wenchuan earthquake 被引量:2
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作者 Lu Shunan Li Shuang +1 位作者 Zhai Changhai Xie Lili 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2013年第1期1-12,共12页
Systematic differences in the duration and frequency content of ground motions from the hanging wall and footwall during the 2008 Wenchuan earthquake are investigated,focusing on the influence of these differences on ... Systematic differences in the duration and frequency content of ground motions from the hanging wall and footwall during the 2008 Wenchuan earthquake are investigated,focusing on the influence of these differences on structural input energy based on the elastic and inelastic energy responses of structures.A comparison of the input energy spectra between the hanging wall and the footwall reveal that the structural input energy on the hanging wall is not amplified due to the short duration and low peak ground velocity to acceleration ratio(V/A).However,the larger demand of structural input energy on the footwall in the range of medium and long periods is observed and the demand increases up to 50% relative to the average level of structural input energy for rupture distances larger than 30 km.The importance of considering the footwall effect on structural input energy when comparing ground motions in the range of medium and long periods is recognized. 展开更多
关键词 Wenchuan earthquake DURATION frequency content hanging wall effect footwall effect input energy
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Impact of seismic excitation characteristics on the efficiency of tuned liquid column dampers
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作者 Ali Kavand S. Mehdi Zahrai 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2006年第2期235-243,共9页
Various types of passive control systems have been used to suppress the seismic response of structures in recent years. Among these systems, Tuned Liquid Column Dampers (TLCDs) dissipate the input earthquake energy ... Various types of passive control systems have been used to suppress the seismic response of structures in recent years. Among these systems, Tuned Liquid Column Dampers (TLCDs) dissipate the input earthquake energy by combining the effects of the movement of the liquid mass in the container, the restoring force on the liquid due to the gravity loads and the damping due to the liquid movement through orifices. In this study, the effects of seismic excitation characteristics such as frequency content and soil condition on the seismic performance of TLCDs are investigated using nonlinear time-history analyses. In this regard, among the past earthquake ground motion records of Iran, 16 records with different parameters were selected. In the structural model developed, the attached TLCD is simulated as a Tuned Mass Damper (TMD) having the same vibration period and damping ratio as the original TLCD. The numerical results show that the seismic excitation characteristics have a substantial role on the displacement reduction capability of TLCDs and they should be considered accordingly in the design of TLCDs. 展开更多
关键词 passive control tuned liquid column dampers seismic excitation characteristics frequency content subsoilconditions seismic performance
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Use of probabilistic and deterministic measures to identify unfavorable earthquake records 被引量:2
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作者 Abbas MOUSTAFA Izuru TAKEWAKI 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2009年第5期619-634,共16页
This study introduces measures to identify resonant (concentration of energy in a single or a few frequencies) or unfavorable earthquake ground motions. Probabilistic measures based on the entropy rate and the geometr... This study introduces measures to identify resonant (concentration of energy in a single or a few frequencies) or unfavorable earthquake ground motions. Probabilistic measures based on the entropy rate and the geometric properties of the power spectral density function (PSDF) of the ground acceleration are developed first. Subsequently, deterministic measures for the frequency content of the ground acceleration are also developed. These measures are then used for identifying resonance and criticality in stochastic earthquake models and 110 acceleration records measured at rock, stiff, medium and soft soil sites. The unfavorable earthquake record for a given structure is defined as the record having a narrow frequency content and dominant frequency close to the structure fundamental natural frequency. Accordingly, the measures developed in this study may provide a basis for selecting records that are capable of producing the highest structural response. Numerical verifications are provided on damage caused to structures by identified resonant records. 展开更多
关键词 Entropy rate Dispersion index Power spectral density function (PSDF) frequency content Unfavorable groundmotion Resonant acceleration Critical accelerogram Energy Damage index
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Decadal Variability of Extreme Precipitation Days over Northwest China from 1963 to 2012 被引量:2
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作者 郭品文 张夏琨 +2 位作者 张书余 王春玲 张晓 《Journal of Meteorological Research》 SCIE 2014年第6期1099-1113,共15页
Daily precipitation data from 153 meteorological stations over Northwest China during summer from 1963 to 2012 were selected to analyze the spatiotemporal distribution of extreme summer precipitation frequency.The res... Daily precipitation data from 153 meteorological stations over Northwest China during summer from 1963 to 2012 were selected to analyze the spatiotemporal distribution of extreme summer precipitation frequency.The results show that the extreme precipitation frequency was regional dependent.Southern Gansu,northern Qinghai,and southern Shaanxi provinces exhibited a high extreme precipitation frequency and were prone to abrupt changes in the frequency.Northwest China was further divided into three sub-regions(northern,central,and southern) based on cluster analysis of the 50-yr extreme precipitation frequency series for each meteorological station.The extreme precipitation frequency changes were manifested in the northern region during the late 1970 s and in the central region from the end of the 1980 s to the 1990 s.The southern region fluctuated on a timescale of quasi-10 yr.This study also explored the mechanism of changes in extreme precipitation frequency.The results demonstrate that stratification stability,atmospheric water vapor content,and upward motion all affected the changes in extreme precipitation frequency. 展开更多
关键词 extreme precipitation frequency Northwest China stratification stability water vapor content atmospheric upward motion
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