排序方式： 共有9条查询结果，搜索用时 15 毫秒
1
1.
A methodology is proposed to determine design earthquakes for site-specific studies such as the siting of critical structures (power plants, waste disposals, large dams, etc.), strategic structures (fire stations, military commands, hospitals, etc.), or for seismic microzoning studies, matching the results of probabilistic seismic hazard analyses. This goal is achieved by calculating the source contribution to hazard and the magnitude–distance deaggregation, showing that, varying the selected frequency and the level of hazard, the reference earthquakes are changed as a result. A procedure is then adopted to minimize the residuals between the uniform hazard spectrum (target motion) and the design earthquake spectrum, to provide a specific earthquake scenario encompassing all the frequencies of the target motion. Finally, some considerations on the use and the influence exerted by ground motion uncertainty (σ) on hazard deaggregation are outlined. 相似文献
2.
Seismic hazard disaggregation in performance‐based earthquake engineering: occurrence or exceedance? 
下载免费PDF全文
下载免费PDF全文 Seismic hazard disaggregation is commonly used as an aid in ground‐motion selection for the seismic response analysis of structures. This short communication investigates two different approaches to disaggregation related to the exceedance and occurrence of a particular intensity. The impact the different approaches might have on a subsequent structural analysis at a given intensity is explored through the calculation of conditional spectra. It is found that the exceedance approach results in conditional spectra that will be conservative when used as targets for ground‐motion selection. It is however argued that the use of the occurrence disaggregation is more consistent with the objectives of seismic response analyses in the context of performance‐based earthquake engineering. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
3.
With the increasing emphasis of performance‐based earthquake engineering in the engineering community, several investigations have been presented outlining simplified approaches suitable for performance‐based seismic design (PBSD). Central to most of these PBSD approaches is the use of closed‐form analytical solutions to the probabilistic integral equations representing the rate of exceedance of key performance measures. Situations where such closed‐form solutions are not appropriate primarily relate to the problem of extrapolation outside of the region in which parameters of the closed‐form solution are fit. This study presents a critical review of the closed‐form solution for the annual rate of structural collapse. The closed‐form solution requires the assumptions of lognormality of the collapse fragility and power model form of the ground motion hazard, of which the latter is more significant regarding the error of the closed‐form solution. Via a parametric study, the key variables contributing to the error between the closed‐form solution and solution via numerical integration are illustrated. As these key variables cannot be easily measured, it casts doubt on the use of such closed‐form solutions in future PBSD, especially considering the simple and efficient nature of using direct numerical integration to obtain the solution. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
4.
Hazard-consistent response spectra in the Region of Murcia (Southeast Spain): comparison to earthquake-resistant provisions 总被引：1，自引：1，他引：0
Jorge M. Gaspar-Escribano Belén Benito Julián García-Mayordomo 《Bulletin of Earthquake Engineering》2008,6(2):179-196
Hazard-consistent ground-motion characterisations of three representative sites located in the Region of Murcia (southeast
Spain) are presented. This is the area where the last three damaging events in Spain occurred and there is a significant amount
of data for comparing them with seismic hazard estimates and earthquake-resistant provisions. Results of a probabilistic seismic
hazard analysis are used to derive uniform hazard spectra (UHS) for the 475-year return period, on rock and soil conditions.
Hazard deaggregation shows that the largest hazard contributions are due to small, local events for short-period target motions
and to moderate, more distant events for long-period target motions. For each target motion and site considered, the associated
specific response spectra (SRS) are obtained. It is shown that the combination of two SRS, for short- and long-period ground
motions respectively, provides a good approximation to the UHS at each site. The UHS are compared to design response spectra
contained in current Spanish and European seismic codes for the 475-year return period. For the three sites analysed, only
the Eurocode 8 (EC8) type 2 spectrum captures the basic shape of the UHS (and not the EC8 type 1, as could be expected a priori).
An alternative response spectrum, anchored at short- and long-period accelerations, is tested, providing a close match to
the UHS spectra at the three sites. Results underline the important contribution of the frequent, low-to-moderate earthquakes
that characterize the seismicity of this area to seismic hazard (at the 475-year return period). 相似文献
5.
The catastrophic nature of seismic risk resides in the fact that a group of structures and infrastructure is simultaneously
excited by spatially correlated seismic loads due to an earthquake. For this, both earthquake-to-earthquake (inter-event)
and site-to-site (intra-event) correlations associated with ground motion prediction equations must be taken into account
in assessing seismic hazard and risk at multiple sites. The consideration of spatial correlation of seismic demand affects
aggregate seismic losses as well as identified scenario seismic events. To investigate such effects quantitatively, a simulation-based
seismic risk model for spatially distributed structures is employed. Analysis results indicate that adequate treatment of
spatial correlation of seismic demand is essential and the probability distribution of aggregate seismic loss can be significantly
different from those based on the assumptions that seismic excitations are not correlated or fully correlated. Furthermore,
the results suggest that identified scenario events by deaggregation in terms of magnitude and distance become more extreme
if the spatial correlation is ignored. 相似文献
6.
Seismic hazard assessment of Tehran,Iran with emphasis on near-fault rupture directivity effects 下载免费PDF全文
下载免费PDF全文 Many destructive earthquakes happened in Tehran, Iran in the last centuries. The existence of active faults like the North Tehran is the main cause of seismicity in this city. According to past investigations, it is estimated that in the scenario of activation of the North Tehran fault, many structures in Tehran will collapse. Therefore, it is necessary to incorporate the near field rupture directivity effects of this fault into the seismic hazard assessment of important sites in Tehran. In this study, using calculations coded in MATLAB,Probabilistic Seismic Hazard Analysis(PSHA) is conducted for an important site in Tehran. Following that, deaggregation technique is performed on PSHA and the contribution of seismic scenarios to hazard is obtained in the range of distance and magnitude. After identifying the North Tehran fault as the most hazardous source affecting the site in 10000-year return period, rupture directivity effects of this fault is incorporated into the seismic hazard assessment using Somerville et al.(1997) model with broadband approach and Shahi and Baker(2011) model with narrowband approach. The results show that the narrowband approach caused a 27% increase in the peak of response spectrum in 10000-year return period compared with the conventional PSHA. Therefore, it is necessary to incorporate the near fault rupture directivity effects into the higher levels of seismic hazard assessment attributed to important sites. 相似文献
7.
Brendon A. Bradley Rajesh P. Dhakal Gregory A. MacRae Misko Cubrinovski 《地震工程与结构动力学》2010,39(6):591-613
A companion paper has investigated the effects of intensity measure (IM) selection in the prediction of spatially distributed response in a multi‐degree‐of‐freedom structure. This paper extends from structural response prediction to performance assessment metrics such as probability of structural collapse; probability of exceeding a specified level of demand or direct repair cost; and the distribution of direct repair loss for a given level of ground motion. In addition, a method is proposed to account for the effect of varying seismological properties of ground motions on seismic demand that does not require different ground motion records to be used for each intensity level. Results illustrate that the conventional IM, spectral displacement at the first mode, Sde(T1), produces higher risk estimates than alternative velocity‐based IM's, namely spectrum intensity, SI, and peak ground velocity, PGV, because of its high uncertainty in ground motion prediction and poor efficiency in predicting peak acceleration demands. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
8.
Somayajulu L. N. Dhulipala Adrian Rodriguez‐Marek Shyam Ranganathan Madeleine M. Flint 《地震工程与结构动力学》2018,47(2):377-396
In probabilistic seismic demand analysis, evaluation of the sufficiency of an intensity measure (IM) is an important criterion to avoid biased assessment of the demand hazard. However, there exists no metric to quantify the degree of sufficiency as per the criterion of Luco and Cornell (2007). This paper proposes a site‐specific unified measure for degree of sufficiency from all seismological parameters under consideration using a total information gain metric. This unified metric for sufficiency supports not only comparison of the performance of different IMs given a response quantity but also assessment of the performance of a particular IM across different response quantities. The proposed sufficiency metric was evaluated for a 4‐story steel moment frame building, and the influence of ground motion selection on the degree of sufficiency was investigated. It was observed that ground motion selection can have a significant impact on IM sufficiency. Because computing the total information gain requires continuous deaggregation across the IM space, an approximate deaggregation technique that allows for a more practical estimation of marginal deaggregation probabilities is proposed. It is expected that the total information gain metric proposed in this paper will aid in understanding the efficiency‐sufficiency relation, thus enabling the selection of a proper scalar IM for a given site and application in probabilistic seismic demand analysis. 相似文献
9.
An efficient method for estimating the collapse risk of structures in seismic regions 总被引：1，自引：0，他引：1
Assessing the probability of collapse is a computationally demanding component of performance‐based earthquake engineering. This paper examines various aspects involved in the computation of the mean annual frequency of collapse (λc) and proposes an efficient method for estimating the sidesway collapse risk of structures in seismic regions. By deaggregating the mean annual frequency of collapse, it is shown that the mean annual frequency of collapse is typically dominated by earthquake ground motion intensities corresponding to the lower half of the collapse fragility curve. Uncertainty in the collapse fragility curve and mean annual frequency of collapse as a function of the number of ground motions used in calculations is also quantified, and it is shown that using a small number of ground motions can lead to unreliable estimates of a structure's collapse risk. The proposed method is shown to significantly reduce the computational effort and uncertainty in the estimate. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
1