Testing of Superelastic Recentering Pre-Strained Braces for Seismic Resistant Design

Over the past decade, the use of shape memory alloys (SMAs) in passive control devices has been explored. Nevertheless, some aspects in regards to the cyclic behavior of SMAs and the effect of pre-straining need to be clarified. In this study, small-scale shake table tests have been performed to explore the effectiveness of SMA bracing systems as compared to steel bracing systems. The reduced-scale experimental results imply that SMAs used in braces are more effective in controlling the response of a steel frame compared with a traditional bracing system. A finite element model (FEM) of the frame is developed in order to compare the analytical results with the shake table tests. Further, the effect of pre-straining the SMA braces is evaluated through both experimental and analytical studies. The results show that pre-straining improves the performance of the frame compared to the nonpre-strained case. However, as the level of pre-straining increases above approximately 1.0% to 1.5%, the benefits of pre-straining decrease compared with low-to-moderate pre-strain levels.     

Shock Response from Pseudodynamic Test Using Momentum Equations of Motion

The feasibility of using pseudodynamic techniques to yield shock responses from impulses is studied herein. A direct integration method is often used to solve the force equation of motion in performing a conventional pseudodynamic test. However, this technique might not be applicable to obtain an accurate shock response from an impulse as a load discontinuity occurs at the end of the impulse. This is because this discontinuity will lead to an extra amplitude distortion and the amount of this amplitude distortion is increased with the increase of time step. Hence, a small time step is needed to reduce the extra amplitude distortion and thus the displacement increment for each time step might be smaller than or as small as the resolution of the displacement transducer. As a result, the displacement increment cannot be accurately imposed upon the specimen and the responses will be contaminated by the noise. In addition, the test duration is drastically increased. Alternatively, this difficulty might be overcome if the momentum equation of motion instead of the force equation of motion is solved pseudodynamically. Hence, an external momentum is used in the solution of the momentum equation of motion. Since the external momentum is a resultant of the time integration of the external force the discontinuity problem will automatically disappear. Consequently, reliable shock responses can be obtained from pseudodynamic tests.     

Experimental Evaluation of Seismic Performance of Squat RC Structural Walls with Limited Ductility Reinforcing Details

This article describes an experimental study carried out on of reinforced concrete (RC) walls of less confining reinforcement than that recommended by ACI 318. A total of eight RC walls with boundary elements comprising of five walls with aspect ratio of 1.125 and three walls with aspect ratio of 1.625 were tested by subjecting them to low levels of axial compression loading and simulated seismic loading, to examine the structural performance of the walls with limited transverse reinforcement. Conclusions are reached concerning the failure mode, drift capacity, strength capacity, components of top deformation, and energy dissipation characteristics of walls on the seismic behavior with limited transverse reinforcement. The influences of axial loading, transverse reinforcement in the wall boundary elements, and the presence of construction joints at the wall base on the seismic behavior of walls are also studied in this paper. Lastly, reasonable strut-and-tie models are developed to help in understanding the force transfer mechanism in the walls tested.     

Relative Displacement Floor Spectra for Seismic Design of Non Structural Elements

Relative displacement floor spectra represent a powerful tool to evaluate the seismic displacement requirements of non-structural elements relative to their attachment points and can be used for displacement-based design of ductile components.

This article examines the displacement floor spectra on single-degree of freedom systems subject to accelerograms of varying intensity. A new method is proposed to predict floor spectra on single degree of freedom supporting structures. The results of nonlinear time-history analyses of a series of case-study structures indicate that the new methodology provides good results.

Future research will aim to validate this approach for multi-degrees of freedom supporting structures.     

国内外游客旅游动机及其差异研究——以西安市为例

深入了解和掌握游客的旅游动机及其特点,对于旅游目的地旅游业的发展具有重要意义。以我国著名的旅游城市西安为例,依据大样本问卷抽样调查一手数据,采用均值分析、探索性因子分析和验证性结构方程模型,对旅游目的地接待的国内游客和外国游客的旅游动机变量类型、变量大小与离散程度及变量关系进行了深入分析,并首次揭示了两类游客群体旅游动机的差异性,从而为认清两类游客群体的旅游心理诉求,提供相应的旅游产品;激发两类游客群体的旅游动机,拓展旅游市场;乃至于旅游目的地旅游业的整体发展提供基础的理论参考。     

浅论中国传统建筑装饰的等级特征

由于传统化的影响,中国传统建筑等级森严,建筑装饰从屋顶到墙壁,从门窗到陈设,都有严格的规定。     

Cultural Imperialism and Heritage Politics in the Event of Armed Conflict: Prospects for an ‘Activist Archaeology’

The production of archaeological knowledge is embedded in a long-standing tradition of colonial encounters. This paper asks how political-economic interests impinge on archaeological work, specifically in the event of armed conflict. To answer this question I discuss commodification of cultural heritage and analyze it as a form of structural violence. I argue that the attitude that allows treatment of archaeological artifacts as saleable items with international owners is part of a strategy of global cultural imperialism. Exemplified by the case of the US-led invasion of Iraq in 2003, this paper shows how the clash of global ‘heritage’ politics with local practices of memorializing the past results in a tension: because capitalist governments consider the locales whose glorious pasts are studied by archaeologists to be culturally inferior, the nexus between (trans-)national actors and local communities is an asymmetrical one. In order to overcome the hegemonic role of archaeology within these dynamics, I propose an ‘activist archaeology’ that enables a political activism grounded in recursivity.     

Structural change and wife abuse: A disaggregated study of mineral mining and domestic violence in sub-Saharan Africa, 1999–2013

Mineral mining may be a mixed blessing for local communities. On the one hand, extractive industries can be a positive economic driver, generating considerable revenues, and opportunities for growth. On the other hand, mining is often thought to be associated with negative effects, such as pollution, and violent conflict. Existing research has shown that mine openings trigger a structural change in employment patterns in Africa, whereby women shift from agricultural work to the service sector, or leave the labor force. However, few if any systematic studies have addressed whether this structural shift may impact the level of violence within the household. Drawing on various versions of resource theory, we argue that mining – through such structural change – may increase women's risk of being abused by their partners. Recent advances in the literature on domestic violence (DV) suggest that prevailing gender norms moderate effects of resources. We test this empirically by matching georeferenced data on openings and closings of 147 industrial mines to individual data on abuse for up to 142,749 women from the Demographic and Health Surveys in 15 sub-Saharan African countries. We find no overall statistically significant effect of mine openings on the risk of partner abuse, although there are heterogeneous effects across countries. Furthermore, mining is associated with increased DV in areas with higher general acceptance of such abuse.     

太原永祚寺无梁殿的建筑形制及结构静力性能研究

本工作以太原永祚寺无梁殿为例,研究中国特有的建筑遗产类型——明代砖砌无梁殿的建筑形制和结构性能。首先采用三维激光扫描仪进行精确测绘,获得其准确的几何尺寸信息。然后结合历史文献资料,对该类型建筑遗产的建筑形制进行分析。另外,通过采用无损检测方法获得砖砌体的材料强度,结合精确测绘获得的几何尺寸信息,采用ANSYS有限元软件建模并对其受力性能进行了模拟分析,获得了该建筑在静力荷载作用下的结构性能。研究结论为该类型建筑遗产的加固修缮提供参考。     

两晋时期建筑构件中的兽面研究

东晋建康兽面瓦当来源于西晋,其源头当在中原洛阳地区新莽时期的壁画兽面。汉晋建筑构件中的兽面使用经历了从地下墓葬到地面建筑的过程,这一过程与汉晋墓葬制度的区域变化有关,其根源在于早期道教的发展。