FRAGILITY ASSESSMENT OF SLAB-COLUMN CONNECTIONS IN EXISTING NON-DUCTILE REINFORCED CONCRETE BUILDINGS

Fragility functions that estimate the probability of exceeding different levels of damage in slab-column connections of existing non-ductile reinforced concrete buildings subjected to earthquakes are presented. The proposed fragility functions are based on experimental data from 16 investigations conducted in the last 36 years that include a total of 82 specimens. Fragility functions corresponding to four damage states are presented as functions of the level of peak interstory drift imposed on the connection. For damage states involving punching shear failure and loss of vertical carrying capacity, the fragility functions are also a function of the vertical shear in the connection produced by gravity loads normalised by the nominal vertical shear strength in the absence of unbalanced moments. Two sources of uncertainty in the estimation of damage as a function of lateral deformation are studied and discussed. The first is the specimen-to-specimen variability of the drifts associated with a damage state, and the second the epistemic uncertainty arising from using small samples of experimental data and from interpreting the experimental results. For a given peak interstorey drift ratio, the proposed fragility curves permit the estimation of the probability of experiencing different levels of damage in slab-column connections.     

日语接续词与副词的比较认识

日语中没有固有的接续词,它都是由其它同类直接转成或由其它同类组合而来,其中副词转成的有很多,但在实际应用中,接续词和副词之间的区别,是很难把握的,成为日语教学中的重点、难点。因此,笔者根据多年教学实践,结合具体实例,分三部分(即定义、构成和用法)对两种词类的异同加以比较,以明确接续词在语法上的作用。     

MOMENT RESISTING WELDED CONNECTIONS: AN EXTENSIVE REVIEW OF DESIGN PRACTICE AND EXPERIMENTAL RESEARCH IN USA,JAPAN AND EUROPE

Welded connections, widely used in seismic moment resisting frames (MRFs) in USA, Japan and Europe, have been extensively investigated during the 1990s in order to improve their performance under severe earthquakes. In order to correctly evaluate the results of experimental research on welded connections, the differences among the American, Japanese and European current practices in designing the frame structural systems and in detailing the beam-to-column connections should be firstly appraised. In this paper, the major aspects characterising the USA, Japan and Europe design practice in moment resisting welded connections are reported, the differences are underlined and the main issues recently addressed in experimental research are reviewed. Among the several parameters which affect the connection performance, attention is focused on the effect of the beam cross-section size. Thus conclusions are drawn in terms of plastic rotation capacity as dependant on the beam size.     

STIFFNESS AND FRACTURE CHARACTERISTICS OF THE NORTHRIDGE STEEL MOMENT RESISTING CONNECTIONS

The Northridge fractures demonstrated the inability of the welded beam-to-column connection, typically used in California prior to the 1994 earthquake, to fully develop the beam's plastic moment and, in some cases, to even reach yield. The unanticipated character of these failures implies that loads at which fracture occurs under Northridge-type conditions as well as the effects the latter has on a building's stiffness need to be quantified. This paper addresses these issues in a quantitive manner. To simplify matters, the behaviour of a simple single degree-of-freedom (SDOF) frame, with connection characteristics modelled in a way that reflects the Northridge conditions, is examined by taking into account the random nature of the connection's resistance to fracture. The fracture event is found to result in a modest reduction in the frame's lateral stiffness, with the post-fracture behaviour being governed by the behaviour of the remaining connecting elements.     

STRUCTURAL RESPONSE AND DAMAGE ASSESSMENT BY ENHANCED UNCOUPLED MODAL RESPONSE HISTORY ANALYSIS

The Uncoupled Modal Response History Analysis (UMRHA) method developed by Chopra et al. is modified in this paper to estimate damage to welded moment-resisting connections in a steel frame (MRSF) subjected to earthquake ground motions. The behaviour of these connections is modelled by a moment-rotation relationship that accounts for the cracking of the beam flange-to-column flange groove weld. The behaviour of the frame is approximated by a sequence of single-degree-of-freedom (SDOF) models for the first three modes to allow for the contribution of higher modes of vibration. The dynamic properties of these SDOF systems are determined by nonlinear static pushover analyses of the building frame. Because of the significant drop in connection strength caused by beam-to-column weld cracking, the pushover procedure uses a changing rather than invariant distribution of horizontal loads, while the structural responses are calculated from shapes that are based on the displaced shape of the frame after damage occurs. The accuracy of the method is demonstrated by a comparison with the results of a nonlinear time history analysis of the frame. This method can be used for rapid assessment of seismic damage or damage potential and to identify buildings requiring more detailed investigation.     

全球关联与全球伦理的可能性探究

本文对学术界许多人倡导的普世同质性的全球伦理观提出质疑与批判,通过对“全球伦理”一词的语义学和经济全球化的研究,探讨了全球伦理发展的可能趋向─—全球意识伦理,并在此基础上论证了其特征、理论的可能性与现实的可行性。     

ASSESSMENT OF THE NATURAL FREQUENCY OF THE SEDIMENTARY COVER IN THE COLOGNE AREA (GERMANY) USING NOISE MEASUREMENTS

Noise measurements were carried out at 381 sites in the Cologne area (Germany) using both short period and broad band sensors. The large number of data allowed both assesment of the influence of different sensors in the site response estimation and to compare the widely used H/V technique with the recently proposed Fourier Phase Spectral Method (FPSM). The results show that short period sensors are able to reliably retrieve site effects at frequencies well below their corner frequencies. Moreover, the H/V method should be preferred to the FPSM in determining the fundamental resonance frequency of soils. Finally, a map showing the resonance frequency distribution in the studied area was drawn using the results obtained applying the H/V technique.     

NATUFIAN INTERACTIONS ALONG THE JORDAN VALLEY

Abstract

Building on recent observations made by Belfer-Cohen and Goring-Morris, this study proposes that a zone of intensive interaction existed between communities in the Jordan Valley during much of the Early Natufian period (c. 12,500–11,000 cal bc). Recently published data demonstrate distinctive and even unique links between open-air Jordan Valley sites. Whereas some models have utilised specific types of material culture (e.g. bone artefacts or art items) to identify cultural provinces in the Natufian, this enquiry uses multiple categories of evidence (site types, shared artefact types, artefacts with close stylistic similarities, embodied behavioural practices, and raw material movements) to propose a Natufian sub-region in the Jordan Valley. The likely existence of a post-Lisan “Damya Lake” is suggested as a rationale for extensive north–south contexts south along the Rift Valley, especially for the transport of heavy materials such as basaltic rock. In the future, scientific techniques such as the isotopic analysis of human skeletal remains, elemental characterisation of raw material source, and reliable dating of excavated sites will prove to be decisive in evaluating the model.     

Europe at the crossroads of three worlds: alternative histories and connections of European solidarity with the Third World, 1950s–80s

Abstract

Over the past few years, there has been growing interdisciplinary interest in the history of European solidarity movements that mobilized on behalf of the ‘Third World’ in the wake of the post-war decolonization process. Focusing on European campaigns against the Vietnam War and Pinochet’s Chile, this article aims at positioning these international solidarity movements in the broader history of North–South and East–West exchanges and connections in Europe during the Cold War. It explores some key ideas, actors and alternative networks that have remained little studied in mainstream accounts and public memories, but which are key to understanding the development of transnational activism in Europe and its relevance to broader fields of research, such as the history of Communism, decolonization, human rights, the Cold War and European identity. It delves into the impact of East–West networks and the Communist ‘First World’ in the discovery of the Third World in Western Europe, analyses the role of Third World diplomacy in this process, and argues how East–West and North–South networks invested international solidarity campaigns on ‘global’ issues with ideas about Europe’s past and present. Together, these networks turned resistance against the Vietnam War, human-rights violations in Pinochet’s Chile, and other causes in the Third World into themes for détente and pan-European cooperation across the borders of the Iron Curtain, and made them a symbol to build a common identity between the decolonized world and Europe. What emerges from this analysis is both a critique of West-centred narratives, which are focused on anti-totalitarianism, as well as an invitation to take North–South and East–West contacts, as well as the role of European identities, more seriously in the international history of human rights and international solidarity.