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41.
用于古建筑琉璃瓦保护的高分子聚合物材料的分析研究 总被引:1,自引:0,他引:1
为探索高分子聚合物用于古建筑琉璃瓦的保护研究,采用所选择的9种有机高分子聚合物对现代黄釉琉璃瓦进行保护处理,分析保护材料的耐光性能及保护后琉璃瓦的憎水性、耐冻融性和化学稳定性等性能,同时选择性能较好的材料用于胎体酥粉古琉璃瓦的保护,分析憎水性、耐冻融性、耐折、抗压强度、透气性以及进行保护机理研究.结果表明,保护材料丙烯酸类材料的Primal SF和1372耐光性能较差;用于现代琉璃瓦保护的Primal SF憎水性和耐冻融性较差;有机硅的耐酸碱性较差;聚氨酯和硅丙乳液的憎水性和耐碱性能较差;氟碳清漆、氟树脂和复配材料的各项性能相对较好;含氟聚合物及其氟树脂为主的复配材料用于胎体酥粉古琉璃瓦保护的憎水性、耐冻融性、耐折、抗压强度和透气性等性能相对较好,保护材料以良好的渗透能力渗入古琉璃胎体内部,有效提高胎体强度,起到填充空隙和防止水分破坏的作用.综合几项指标,含氟聚合物及其复配材料的各种性能优良,为选择中国古建筑琉璃瓦的保护材料提供科学依据. 相似文献
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S. R. Uma Stefano Pampanin Constantin Christopoulos 《Journal of Earthquake Engineering》2013,17(7):1092-1111
Recently, the importance of considering residual (permanent) deformations in the performance assessment of structures has been recognized. Advanced structural systems with re-centering properties as those based on unbonded post-tensioning tendons are capable of controlling or completely eliminating residual deformations. However, for more traditional systems, which count for the vast majority of buildings, residual deformations are currently considered an unavoidable result of structural inelastic response under severe seismic shaking. In this article, a probabilistic framework for a performance-based seismic assessment of structures considering residual deformations is proposed. The development of a probabilistic formulation of a combined three-dimensional performance matrix, where maximum and residual deformations are combined to define the performance level corresponding to various damage states for a given seismic intensity levels, is first presented. Combined fragility curves expressing the probability of exceedence of performance levels defined by pairs of maximum-residual deformations are then derived using bivariate probability distributions. The significance of evaluating and accounting for residual deformations within a Performance-based Earthquake Engineering (PBEE) approach is further confirmed via numerical examples on the response of Single Degree of Freedom (SDOF) systems, with different hysteretic behavior, under a selected suite of earthquake records. Joined fragility curves corresponding to various performance levels, defined as a combination of maximum and residual response parameters, are derived while investigating the effects of hysteretic systems and strength ratios. It is observed that stiffness degrading Takeda systems result in lower residual deformations than elasto-plastic systems and show lower probability of exceeding a jointed maximum-residual performance level. For a chosen performance level, Takeda systems with higher strength ratios show better performance, particularly with lower intensity of excitations. 相似文献
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Virgiliu Bîrlădeanu 《History & Anthropology》2013,24(1):36-55
In the context of the forceful dispute over national identity in Moldova, the Communist government of 2001–2009 aimed to articulate a project of “Moldovan identity” which was raised to the level of a state ideology. In the spirit of Soviet propaganda, this project was implemented through public holidays and celebrations. The following analysis examines two case studies—the Wine Festival and the Independence Cup—by discerning the performative practices designed as part of the nation-building project in Moldova between 2005 and 2009. Organized at the official level, but with the strong assistance of mass media, these public events were intended to win the support and attention of Moldovan society by employing rituals and performances similar to those of the Soviet period. The paper addresses the characteristics and mechanisms of these performative practices, and considers why this nation-building project did not achieve its goals, but instead caused tension and disputes. One of the main aims is to understand how the Communist government sought to redefine “the Moldovan nation”. 相似文献
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Bob Simpson 《History & Anthropology》2013,24(3):301-316
This article sets out to explore the strategic creativity that underlies supposedly invariant ritual performance. The ethnographic focus is on a group of Sri Lankan ritual specialists and the way they present the past in terms of mythical, historical and genealogical relationships that give power and legitimacy to their performances of healing rituals in the present. The analysis brings together local notions of “tradition” with ideas of performance and embodiment. The conclusion takes up the idea that, far from being the dead weight of tradition, invariance is a performative illusion of considerable ingenuity and persuasive power. Indeed, it is a fundamental means whereby the authority and power of ritual is maximized in performance. 相似文献
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Anne Clément 《History & Anthropology》2013,24(2):73-100
This paper aims to rethink “peasant consciousness” in colonial Egypt, through a study of the performance of folksongs by Upper Egyptian agricultural workers on the archaeological excavation sites of Karnak and Dendera at the turn of the twentieth century (1885–1914). Mainly based on a historical‐anthropological analysis of songs collected between 1900 and 1914 by the French archaeologists Maspéro and Legrain, this essay proposes a new understanding of subaltern consciousnesses as fragmented objects constructed through a dialectical relationship of power and resistance as performed by the various actors present on the scene. Drawing its inspiration from the work of contemporary ethnomusicologists (Finnegan 1977, 1992; Slyomovics 1987) and relying on the framework shaped by their use of oral‐formulaic and speech‐act theories, this study conceives of the performance, reception and collection of the songs as a crucial locus of encounter, interaction and negotiation between the local landless peasants employed as daily workers on the excavation sites, and the colonial administrators of the Antiquities Service during the key period of transition from corvée to contract labour. 相似文献
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Ali Sahin Tasligedik Umut Akguzel Weng Yuen Kam Stefano Pampanin 《Journal of Earthquake Engineering》2018,22(3):454-487
Strength hierarchy assessment is a method that can be utilized to identify the weakest structural element at a reinforced concrete (RC) beam-column joint. The method was extensively used in various research activities at the University of Canterbury, which mainly involved beam-column joint subassembly tests. However, this method required improvements and refinements in order to be adopted in multi-story building applications. In this paper, the improvements made to the method are reported. In the improved method, capacity of the weakest element at every beam-column joint in an RC frame building can be related to the corresponding global base shear demand. The method has been illustrated via two example applications: an RC frame lacking joint shear reinforcement and a modern RC frame with adequate joint shear reinforcement. The case study examples confirmed the accuracy and the effectiveness of the method. 相似文献
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Federico Valenzuela-Beltrán Sonia E. Ruiz Alfredo Reyes-Salazar Edén Bojórquez 《Journal of Earthquake Engineering》2018,22(1):36-62
A reliability-based methodology to estimate strength amplification factors for structures with asymmetric yielding is proposed. The approach is based on structural demand hazard analyses. Nonlinear time-history analyses of tridimensional simplified systems are carried out. The effects of two orthogonal components of the seismic ground motions and soil-structure interaction, are considered. Results show that the expected ductility demand of systems with asymmetric yielding may be much higher than those of symmetric systems. A simplified mathematical expression (which is function of the ratio between the fundamental vibration period of the system and that of the soil, ductility demand, and level of asymmetric yielding) is proposed to estimate the amplification factors. The expression is applied successfully to a 9-story reinforced concrete building exhibiting asymmetric yielding produced by tilting. 相似文献
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Daniel Antón Benachir Medjdoub Raid Shrahily Juan Moyano 《International Journal of Architectural Heritage》2018,12(5):790-805
It is stated that 3D recording and modeling of heritage buildings entail accurate building models (as-built). However, this paper presents an analysis of the 3D modeling accuracy for the creation of historical building information models (HBIM), considering the complexity and the deformations of historical buildings, using point cloud data and BIM tools. The 3D modeling processes analyzed are based on a three-stage semi-automatic approach leading to the generation of HBIM, including manual and automatic processes. The three stages consist of: (a) optical and terrestrial laser scanning; (b) meshing processes; and finally (c) 3D solid modeling to be assembled into HBIM. Next, this approach analyzed the mesh deformations generated automatically in comparison to the initial point cloud data. The deformations and the accuracy evaluation have been undertaken using different commercial software. Finally, our modeling approach shows that it can improve the accuracy of the 3D models achieved using existing BIM technologies. 相似文献
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肯尼迪政府组建和平队,以志愿者的形式,向不发达国家提供所谓“中等人力资源”,进行技术援助,实际上是对战后美国对外援助工作反思的结果,同时也为美国对外援助注入了新的内容。它所涉及的更为深层的考虑,则是广大不发达国家未来的发展道路问题,即这些国家以什么样的方式实现现代化,是以美国为代表的资本主义发展模式,还是以苏联或中国为代表的社会主义发展模式。肯尼迪政府希望,通过和平队的工作,向第三世界国家展示美国的现代化经验和技术,诱导第三世界国家走美国式的现代化道路。 相似文献