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1.
Vector-valued ground motion intensity measures (IMs) are developed and considered for efficiently predicting structural response. The primary IM considered consists of spectral acceleration at the first-mode structural period along with a measure of spectral shape which indicates the spectral acceleration value at a second period. For the IM to effectively predict response, this second period must be selected intelligently in order to capture the most relevant spectral shape properties. Two methods for identifying effective periods are proposed and used to investigate IMs for example structures, and an improvement in the efficiency of structural response predictions is shown. A method is presented for predicting the probability distribution of structural response using a vector IM while accounting for the effect of collapses. The ground motion parameter ε is also considered as part of a three-parameter vector. It is seen that although the spectral shape parameter increases the efficiency of response predictions, it does not fully account for the effect of ε. Thus, ε should still be accounted for in response prediction, either through informed record selection or by including ε in the vector of IM parameters.  相似文献   

2.
The assessment of the seismic performance depends on the choice of the earthquake Intensity Measure (IM). During the past years many IMs, which take into account not only earthquake characteristics but also structural information, have been proposed. However, no consensus on which IM is the best predictor of the seismic response exists. Along these lines, the objective of this paper is to present the various developed scalar structure-specific seismic IMs and the problems associated with their use in practice, so that the engineer may become familiar with them and their implications in the context of Performance-Based Earthquake Engineering.  相似文献   

3.
The seismic assessment of a road network depends largely on the characterization of the fragility of its bridge components. The accuracy of bridge seismic demand estimates and the use of proper intensity measures (IM) will significantly influence such task. The available literature has mainly focused on buildings or a limited number of bridge configurations and IMs, which may not be representative for bridge portfolio assessment studies. In this paper, the correlation quality between a larger pool of traditional and innovative IMs and the nonlinear dynamic response of typical Italian RC bridges is investigated to identify the best-performing IMs.  相似文献   

4.
Empirical correlations between the frequency-content parameters of earthquake ground motions and amplitude-, cumulative-, and duration-based intensity measures (IMs) are examined in this study. Three commonly used scalar frequency-content parameters are considered, namely the mean period (Tm), the average spectral period (Tavg), and the smoothed spectral predominant period (T0). It is found that the frequency-content parameters have weakly negative correlations with high-frequency IMs such as peak ground acceleration (PGA) and spectral accelerations (SAs) at periods smaller than 0.3 s, low-to-moderate positive correlations with peak ground velocity (PGV) and SA within a period range of 0.5 s–10 s, negligible correlations with cumulative-based IMs, and weakly positive correlations (in the vicinity of 0.1–0.3) with significant durations. Simple piecewise parametric equations are proposed to fit the empirical correlations of Tm, Tavg, and T0 with SA over the entire period range. The presented correlation results and parametric models enable the frequency-content parameters to be easily used in various applications such as ground-motion selection and vector-based probabilistic seismic hazard analysis.  相似文献   

5.
Children's independent mobility (IM) lacks a standardised definition and measurement protocol. Interactive mapping applications can capture geographically defined mobility data. In this study of 219 children, independent parental licences (IM Licence) and allowances to travel to certain locations unsupervised (IM Index) were collected through a questionnaire, and compared to IM-roaming areas derived from the Visualisation and Evaluation of Route Itineraries, Travel Destinations, and Activity Spaces (VERITAS-IM) mapping application. Significant relationships were found between the VERITAS-IM-derived measures and traditional measures of IM (IM Licence and IM Index). Results suggest the perceived degree of children's IM is heavily dependent on the assessment method and a combination of methods should be considered.  相似文献   

6.
The unseating of decks is one of the most prevalent failure modes of bridges after earthquake events, as observed in the 2010 Chile Earthquake. Damaged bridges in Chile often had skew angles and were supported on elastomeric bearings. Similar bridge construction practices with decks supported on elastomeric bearings are also common in the central and eastern U.S. (CEUS). The seismic displacement demands on skewed bridges are more complicated than those on bridges without skew angles due to the coupling of translational modes with the rotational mode of vibration. The study presented in this article seeks to understand the seismic response of skewed bridge decks supported on elastomeric bearings. The scope of the study is limited to one- and two-span bridges, which constitute a large portion of bridge inventory in the CEUS. The vibration modes of skewed bridge decks are derived in closed form and the modes are compared when the gaps between the bridge deck and the abutment are open and when one of the gaps is closed due to seismic excitation. Nonlinear response history analyses are carried out to understand the effects of vertical ground motion, skew angles, aspect ratios, and different ground motion types on the seismic displacement demand in these cases. Amplification factors that approximate the increase in the displacement demand due to the skew angle are proposed.  相似文献   

7.
This study proposes an “optimal” spectral acceleration-based intensity measure (IM) to assess the collapse capacity of highly inelastic frame structures vulnerable to the P-delta effect. The IM is derived from the geometric mean of the spectral pseudo-acceleration over a certain period interval. The lower bound period of the averaging interval is related to the mode in which 95% of the effective modal mass is exceeded. The upper bound period is 1.6 times the fundamental period. This IM provides minimum, or close to the minimum, dispersion for frames with different fundamental periods of vibration, or number of stories.  相似文献   

8.
I present in this paper a non-reductionist framework of eight nested modes of evolution that have successively emerged to organize the reproduction of all organisms, from the blue-green algae to our societies. The processes of biological, “Darwinian” evolution are those of drift during reproduction, and of selection. The key unit of evolutionary time is the generation, and its locus is the organisms' life-cycle setup. Different life-cycle setups support different mechanisms of reproduction, and therefore different modes of evolution. By tracing the different life-cycle setups attested throughout life's history, we can characterize the successive modes of evolution with which they are associated as follows: basic; reptilian; archaic mammalian; progressive mammalian; sociocultural; extrasomatically enhanced sociocultural; tinkering; and finally parabiological. These successively emerging modes govern a progressively reduced number of life-forms. The first four modes are “Darwinian” in the strict sense. The fifth, or sociocultural mode, which governs whales and elephants' societies in addition to hominoids, is already not “Darwinian” in the traditional sense. The last three modes have emerged with the genus homo, through the progressive extension of its life-cycle setups. The present framework is to be used heuristically, as a prism with which to separate the evolutionary spectrum of the constituent elements of human behavior. An example of such a behavioral evolutionary spectrum is presented in conclusion, and used to compare the present framework with those recently proposed by Maynard Smith and Szathmáry and by Foley.  相似文献   

9.
Abstract

In the 2000s, contemporary art institutions have flourished in Istanbul. New museums (mostly private) and art galleries have been created; biennials and fairs of contemporary art have attracted a growing number of visitors. To what extent could this fostering of culture be linked with the “Bilbao effect”? To what extent are the promoters of these cultural investments betting on economic development and urban regeneration through these projects? Focusing on the Istanbul Modern Art Museum (IM), this article analyses the process of its creation and its potential impact on its environment. It argues that the development of culture investments in modern arts in Turkey is mainly due to the private initiatives of large industrial groups and the wealthiest families, most of the time with political support. More than the expected economic impact of cultural investments, the main reason for these public–private collaborations is the symbolic dimension that contemporary art provides to a country which strives to be perceived as modern, developed and European. From the IM to Istanbul European Capital of Culture 2010, cultural investments are a means of strengthening an international image in the context of the “membership” negotiations between “Turkey and the European Union”.  相似文献   

10.
2003年在奉节县宝塔坪遗址发掘一批墓葬.IM1028是土坑墓,出土陶器和铜铃,年代在战国晚期到秦代.IM9001是石室墓,出土陶器皿和陶俑,年代在东汉.  相似文献   

11.
为了回答如何判别旅游扶贫模式、旅游扶贫模式是否影响旅游扶贫效应等问题,提出了由区位—产业—文化组成的旅游扶贫资源多要素协同框架作为判别旅游扶贫模式的依据,以此为指导,利用访谈数据,将恩施州南部4县的22个旅游扶贫重点村划分为4种模式:优势景区依托模式、生态农业依托模式、民宿农家乐依托模式和民族文化依托模式。而后,利用问卷调查数据,运用方差分析法比较了不同模式扶贫村居民的旅游扶贫效应感知差异,结果发现:①不同旅游扶贫模式村居民对经济收益、经济成本、环境成本和社会成本的感知具有显著差异,说明旅游扶贫模式是影响旅游扶贫效应的因素;②与其他两种模式村相比,优势景区、生态农业依托模式村居民的旅游扶贫经济效益感知更高,同时经济、环境或社会成本感知也更高,表明旅游扶贫在带来经济效益的同时,也带来了较高的经济、环境和社会成本。最后,提出了促进民族地区旅游扶贫工作改进的对策建议。  相似文献   

12.
In this paper principal component analysis (PCA) and singular value decomposition (SVD) are used to define the importance of the variables contributing to the relationship between the transient latent and sensible heat fluxes and to show their temporal and spatial variation. SVD is offered as an alternative means of isolating spatial and temporal structures in data with the advantage that it can depict simultaneous space‐time variations that are aggregates of the results produced by PCA. Both methods of analysis produced two very important uncorrelated modes of variability in January and July, indicating that the transient heat fluxes are influenced by few controlling factors. We suggest that these modes of variability represent the influences of the meridional temperature gradient, atmospheric moisture, and activity within the source and sink regions of the transient heat fluxes. The physical relationships between the heat fluxes that appear to represented by the statistical modes of variability are discussed.  相似文献   

13.
Children's time and freedom for independent neighbourhood activity is severely declining, which may be adversely impacting their healthy development. This study integrates GPS activity monitoring and environmental analysis in a geographic information system with activity diaries, annotated maps, surveys, and map-enhanced interviews to conduct a deep pattern analysis of children's habitual neighbourhood behaviour (n?=?23; aged 9–13 years) from each an urban and suburban school neighbourhood within London, Canada. Patterns in children's primary activities and settings, independent mobility (IM) levels, and perception and use of neighbourhood affordances are examined. Participants note a diverse range of local independent destinations, but habitually spend little time playing outdoors in neighbourhoods. Local activity related to free time available, perception of activity affordances, and license to travel independently. Social and environmental conditions of children's micro-neighbourhoods influenced independent destinations and domains. Neighbourhood planning should promote diversity of activity affordances and address conditions that support increased IM for youth.  相似文献   

14.
A methodology is presented for assessing the seismic vulnerability of inventories of contents to multiple failure modes. An ordering method to find out probabilities of failure of a conditional mode upon the survival of the other modes is applied. The procedure considers the statistical correlation of failure modes due to the dynamic response, such as sliding and/or overturning, of contents and also to non structural components. This methodology was applied to inventories of four types of occupancy (house, school, office, and hospital) located in Mexico City, considering that all contents are situated at ground level. Expected damage functions for these inventories show large differences between them, the house and school inventories being the least vulnerable, and the hospital inventory, the most vulnerable, even for low intensities.  相似文献   

15.
徐海英  周潮 《人文地理》2019,34(4):89-96
全球生产网络(GPN)2.0认为实现从低水平到高水平动态战略耦合是区域发展的动因。该分析框架认为应从垂直(组织)和水平(空间)两个维度来分析企业价值捕获轨迹,从而分析特定区域的战略耦合模式。选取62家江苏省韩国投资汽车行业企业,采用GPN 2.0分析框架分析企业价值捕获轨迹,并对比苏北和苏南GPNs和区域发展战略耦合的模式差异。研究发现:苏北处于“结构性耦合”阶段,苏南处于“功能性耦合”阶段。苏北和苏南应该采取不同发展战略,为实现更高水平的战略耦合做好准备。  相似文献   

16.
This paper addresses the application of a Bayesian parameter estimation method to a regional seismic risk assessment of curved concrete bridges. For this purpose, numerical models of case-study bridges are simulated to generate multiparameter demand models of components, consisting of various uncertainty parameters and an intensity measure (IM). The demand models are constructed using a Bayesian parameter estimation method and combined with limit states to derive the parameterized fragility curves. These fragility curves are used to develop bridge-specific and bridge-class fragility curves. Moreover, a stepwise removal process in the Bayesian parameter estimation is performed to identify significant parameters affecting component demands.  相似文献   

17.
How New is the New Local Governance? Lessons from the United Kingdom   总被引:1,自引:0,他引:1  
In recent times, a conventional wisdom concerning the governance of cities has emerged. It revolves around the contention that policy and planning frameworks are increasingly closed off from public and democratic accountability, in order to facilitate the pursuit of efficiency over equity objectives. The implication is that 'old' styles of governance were more open and accountable, while the 'new' seek to close off debate and streamline procedures. Yet the evidence to sustain such claims seems limited; this paper situates the policies and practices of local government in the UK within a historical perspective, and develops the contention that the claimed differences between old and new styles of governance are overdrawn. Using empirical material from two UK cities, we demonstrate that there are significant continuities in the procedures and practices of policy-makers, in terms of policy objectives, styles and modes of accountability. In this sense, greater clarity is required in terms of what constitutes both the old and new modes of local governance in the British cities.  相似文献   

18.
This article focuses on the optimum design of bridge abutments when subjected to earthquake loading. Planar failure surface has been used in conjunction with modified pseudo-static approach to compute the seismic active earth pressures on an abutment. The proposed modified Mononobe-Okabe method considers the effects of strain localization in the backfill soil and associated post-peak reduction in the shear resistance from peak to residual values along a previously formed failure plane, phase difference in shear waves, and soil amplification along with the horizontal seismic accelerations. Four modes of stability viz. sliding, overturning, eccentricity, and bearing capacity of the foundation soil are considered in the analysis. The influence of various design parameters on the seismic stability of abutments is presented. The optimum values of base width of the abutment needed to maintain the stability are obtained against four modes of failure, based on the suggestions of Japan Road Association, Caltrans Bridge Design Specifications, and U.S Department of the Army.  相似文献   

19.
The absence of studies investigating the influence of political participation on individuals’ perceptions of political efficacy constitutes a significant gap in our knowledge of political behaviour. While many researchers have investigated the influence of efficacy on political participation, and there has been some endeavour to examine the reciprocity of the relationship between the variables, none has estimated a comprehensive model of the impact of individuals’ participation is different kinds of political activity on different aspects of their perceptions of political efficacy. We redress these particular deficiencies in our knowledge of political behaviour, investigating the influence of participation in three different modes of activity—partisan activism, community activism and political extremism—on individuals’ perceptions of internal and external efficacy; that is, their perceptions of political self‐competence and system responsiveness. Our findings confirm that the relationships between different modes of participation and efficacy are both reciprocal and varied, and that they vary in ways which have important implications for theories of participatory democracy.  相似文献   

20.
An equivalent linearization procedure is developed for predicting the inelastic deformations and internal forces of capacity-designed structures under earthquake excitations. The procedure employs response spectrum analysis, and mainly consists of the construction of an equivalent linear system by reducing the stiffness of structural members that are expected to respond in the inelastic range. These members are well defined in structures designed with capacity principles. Maximum modal displacement demands of the equivalent linear system are determined either from the equal displacement rule, or from independent nonlinear response history analysis of SDOF systems representing inelastic modes.

Predictions obtained from the proposed equivalent linearization procedure are evaluated comparatively by using the results of nonlinear response history analysis as benchmark, linear elastic response spectrum analysis and conventional pushover analysis. The deformations and capacity controlled actions of a 12-story symmetrical plan concrete frame and a 6-story unsymmetrical plan concrete frame are obtained by each method under 96 strong ground motions. It is observed that the proposed procedure results in better accuracy in estimating the inelastic seismic displacement response parameters and capacity controlled forces than the other two approximate methods.  相似文献   

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