Seismic Overstrength of Shear Walls in Parking Structures with Flexible Diaphragms

The objective in current design practice for parking structures is that energy is dissipated through the formation of plastic hinges at the base of shear walls while floor diaphragms remain elastic and are vertically supported by a combination of shear walls and gravity resisting columns. Unfortunately, this objective is not always achieved due to inaccuracies in current methods for calculating demands on shear walls and in calculating the capacity of shear walls (IBC 2003 International Building Code. International Conference of Building Officials. Whittier, CA.  [Google Scholar], ACI code). When demands are overestimated and capacity underestimated, then diaphragm can fail prior to flexural yield of shear walls as was observed in several parking structures in the 1994 Northridge earthquake.

Eigenvalue and inelastic dynamic response analyses were performed in order to investigate the effects of diaphragm flexibility on wall responses and of wall overstrength on diaphragm responses. The elongated periods of parking structures due to diaphragm flexibility were found to significantly decrease seismic force demand on shear walls relative to what is calculated using codes of practice in which diaphragms are assumed to be rigid. This leads to the over design of shear walls, which further compounds the problem by preventing the flexural yielding of these walls and thereby driving inelastic response to diaphragms. Various degrees of diaphragm flexibility, shear wall layout, seismic zone, and the number of stories were considered in these analyses.

Inelastic static pushover analyses were preformed to investigate the design and capacity evaluation of shear walls. The results illustrate that the shear capacity of walls may be close to twice that calculated by codes of practice. The largest overstrengths were observed in shear walls with low height-to-length ratios in which a significant portion of the lateral load was taken by direct strut action to the foundation and without placing demands on the longitudinal tension reinforcement in the shear walls. The article concludes that methods in codes of practice for calculating shear wall demands and capacities need to be improved if good seismic performance of parking structures is to be achieved.     

西汉张安世墓葬M1墓室内的大气环境调查

了解待发掘封闭墓葬内的大气环境,可为考古发掘和文物保存环境研究提供科学依据。西汉张安世墓园中的M1墓葬是一座未被盗扰的墓室,本研究在墓室开启前,有针对性地监测了墓室内的微气候参数和大气污染物。结果显示,相对于外界大气,密闭的墓室内低温、高湿、缺氧,且酸性气态污染物浓度较低。因此,在考古发掘及后续保存文物时,应针对不同文物材料采取密闭容器、保湿、避光等措施,避免由于环境骤变导致文物的风化损坏。本研究建立的待发掘墓葬大气环境测试体系及基础数据,可为相关考古和文保工作提供有益的借鉴。     

Negotiating belonging and perceptions of citizenship in a transnational world: Singapore,a cosmopolis?

The complex mappings of inflows and outflows of people, capital, images and ideas in global city spaces create particular challenges for nation-states that are deeply embedded in the international circuit of capital. Through an empirical study of Singapore, an aspiring global city-state, I offer an analysis of how the state-sponsored cosmopolitan project is contested by Singapore citizens. I also present evidence to highlight the contradictions of belonging and citizenship in a transnational world, with particular reference to the postcolonial racial and nationality dynamics that inflect these discourses.

Négocier l'appartenance et les perceptions de la citoyenneté dans un monde transnational: Singapour comme ville cosmopolite?

Les mappages complexes des mouvements des personnes, du capital, des images et des idées à travers les espaces urbains mondiaux posent un défi particulier aux états-nations qui sont très fortement intégrés dans le circuit international du capital. Singapour, ville-état mondiale en croissance, est le sujet d'une étude empirique dans laquelle je présente une analyse du projet cosmopolite soutenu par l'état et comment ce projet est contesté par les citoyens de Singapour. Je présente également des éléments de preuve pour faire ressortir les contradictions entre l'appartenance et la citoyenneté dans un monde transnational, en précisant entre autres les dynamiques qui touchent aux identités raciales et nationales postcoloniales qui pèsent sur ces discours.

Mots-clefs: appartenance, citoyenneté, mobilité transnationale, cosmopolitanisme, Singapour.

La negociación de pertenencia e ideas de ciudadanía en un mundo transnacional: Singapur, ¿un cosmópolis?

Los complejos mapeos de la entrada y salida de personas, capital, imágenes e ideas en los espacios de ciudades globales crean desafíos particulares para naciones-Estados, los cuales están estrechamente vinculados al circuito internacional de capital. Por un estudio empírico de Singapur, que aspira a ser reconocido como ciudad-estado global, ofrezco un análisis de cómo los ciudadanos de Singapur contestan este proyecto cosmopólito patrocinado por el Estado. También presento pruebas para destacar las contradicciones inherentes en las nociones de pertenencia y ciudadanía en un mundo transnacional, con referencia particular a la dinámica racial y de la dinámica de nacionalidad poscolonial que salpican estos discursos.

Palabras claves: pertenencia, ciudadanía, movilidad transnacional, cosmopolitanismo, Singapur.     

Atmospheric deterioration of Qin brick in an environmental chamber at Emperor Qin's Terracotta Museum, China

Potential mechanisms for the changing appearance of Qin terracotta was evaluated on simulated bricks with, SO₂, NH₃, O₃, and a NH₃/O₃ mixture for total dosages of 2.2–5.4 ppm-years. Changes in the surface composition and appearance were evaluated with scanning electron microscopy/energy dispersive X-ray analysis (SEM–EDX) and X-ray photoelectron spectroscopy (XPS). No observable changes with O₃ exposure were found. Sulfate as sulfur and ammonium as nitrogen increased by 1.2 at% and 0.8 at% of the surface deposit as determined by XPS. O₃ did not have a detectable effect by itself, but when combined with NH₃, NO₃ as nitrogen increased by 1.5 at%, indicating a strong oxidation of NH₃ to nitric acid. The combination of outdoor O₃ infiltration with indoor NH₃, presumably from the visitors, appears to have a greater potential for damage than either pollutant by itself. SEM–EDX mapping of the surface showed sulfur associated with calcium and magnesium compounds after SO₂ exposure, but not before. More detailed microscopic examination showed this primarily in the form of gypsum, especially near cracks and pits in the surface. Both of these mechanisms are probably among the causes of changes in terracotta appearances since they were unearthed in 1974.     

A Model for Measuring the Sustainability Level of Historic Urban Quarters

The main aim of this paper is to propose a model for measuring the sustainability level of historic urban quarters and to indicate an appropriate strategy for their revitalization. Based on this aim, this study first presents the theoretical review on the concept of “revitalization”, and its relationship with sustainability; next, it introduces the characteristics, role, selection process and scaling method of sustainability indicators, which are essential for measuring the level of sustainability. The paper then, as the main contribution of this paper, proposes the model for measuring the level of sustainability in historic urban quarters and determines some proposals to achieve revitalized and sustainable historic urban quarters. Depending on the proposed model, there is a direct relationship between type and the level of obsolescence (revitalization) and the level of sustainability in the physical, economic and social structures of a particular area. Therefore, when the level of sustainability is high in any one of these three structures, it means that the level of obsolescence is low in the same structures of an historic urban quarter. The result of this paper leads us to say that, the level of sustainability is a new (additional) input in the strategic planning process of revitalization and sustainable urban revitalization of historic urban quarters. Finally, the paper concludes with a brief summary on the general arguments of the paper.     

The Role of Pattern‐Welding in Historical Swords—Mechanical Testing of Materials Used in Their Manufacture

Pattern‐welding is a well‐known technique that was widely employed in the manufacture of swords. While the decorative effect of genuine pattern‐welding (employing phosphoric iron) is indisputable, to date its reinforcing effect is rather unclear. In order to understand this issue better, wrought iron, phosphoric iron, steel and various pattern‐welded samples were prepared and mechanically tested, and the results obtained are discussed in detail. Both the mechanical testing and the long‐term metallographic investigation of medieval swords suggest that pattern‐welding does not have any significant positive effect on the mechanical properties of swords and we should consider it a primarily decorative technique.     

How Regional Innovation Systems Play a Relative Competitive Role Within Knowledge Networks

This study aims to explain how specific regional innovation systems (RISs) play relative important role in the knowledge network within European regions. EC encourages the interactions between regions and develop toward a cohesion balance. The whole Europe can be taken as a knowledge network that consists of different RISs possessing diversified resources. The existences of hierarchical relationships between different regions seem to lead us to explain whether the path toward higher-order position can be done by RISs to shape the regional competence in specific technological fields. We establish the datasets on the basis of patent data (from EPO) and REGIO database. Regional-level dataset, including 129 regions, helps to explore how different RIS develop their technological paths, and whether locational economic factors, technological conditions, and local innovativeness help RISs toward high-order position in the network. In addition, we also explore the role of the interaction of local factors for RISs in developing network position in Europe.     

韩国的当代中国政治研究述评

迄今为止,还没有对韩国的中国政治研究状况做出评估。韩国的当代中国政治研究值得关注至少有以下三个理由:第一,韩中关系在过去十多年取得了非同寻常的扩展;第二,在中国学习的外国学生中,韩国留学生的数量最多;第三,尽管刚刚起步,越来越多的韩国学者在当代中国研究的主流英文期刊如《中国季刊》(The China Quarterly)和《中国杂志》(The China Journal)上发表文章。本文主要对三类学术成果进行     

出土饱水云南松的超微构造特征

对云南剑川县出土的木质文物进行了研究,从超微结构层面更深入地解析了饱水古木的降解情况。出土的云南松(Pinus yunnansis)古木在饱水环境中淹埋了4 000多年。降解主要发生在晚材管胞,而且降解在晚材部分并不均匀:一些未降解的完好管胞分布在降解严重的管胞中。透射电镜观察显示:降解从S1/S2和S2/S3的界面开始;对于一些降解较严重的管胞,到腐朽后期细胞次生壁全部发生降解,只留下复合胞间层;细菌侵蚀是云南松饱水古木降解的主要原因。固体核磁共振结果表明:纤维素和半纤维素降解严重,木质素也出现了一定程度的降解。本研究可为其后续的加固保护提供科学的参考依据。