Effects of Different Record Selection Methods on the Transverse Seismic Response of a Bridge in South Western British Columbia

The seismic response of a continuous 4-span bridge designed according to the current Canadian seismic provisions is investigated using Incremental Dynamic Analysis (IDA). Different earthquake types, including shallow crustal events, interface Cascadia subduction, and deep inslab subduction are considered. The median collapse capacities calculated using different record selection methods including Conditional Mean Spectrum (CMS)-based, Uniform Hazard Spectrum (UHS)-based, and epsilon-based methods are compared. The use of the epsilon-based method generally resulted in the highest collapse capacity predictions, but the CMS-based method was less sensitive to the number of records considered in the IDA.     

胶研水对几种传统纸张性能的影响

由明矾和胶料配制而成的胶矾水,是书画绘制、装裱和修复过程中经常使用的材料。胶矾水具有防腐、固色和增加机械力度等功能,但对纸质文物的耐久性有一定的影响。本研究选用宣纸、桑皮纸和连史纸等代表性的传统手工制纸,在它们的表面分别涂敷不同浓度的胶矾水,经干热老化后,对比分析它们的酸碱度、白度、耐折度和抗张强度的变化,揭示胶矾水对这几种手工纸张性能的影响,进而探讨其影响机理。研究结果表明,胶矾水将增加纸张的酸度、降低纸张的白度,明胶水能提升纸张的机械强度,而不同浓度明矾对纸张机械强度的影响存在差异。     

中国文化自然遗产管理评价的指标体系初探

化和自然遗产管理的研究引起学术界重视。目前献集中于研究转型期遗产管理的组织结构的调整,但缺少在管理机制的设计和操作层面上开展研究。本试图从遗产管理绩效评估入手开始对遗产管理激励机制的探索。初步构建了以遗产保护为基本目标和以社区发展、游客管理和经营开发为贡献目标的遗产管理评价指标体系,并对评价的原则和关键指标确定等进行思考。     

Direct Displacement-Based Design of Buildings with Different Seismic Isolation Systems

A displacement-based design (DBD) procedure for buildings equipped with different seismic isolation systems is proposed. It has been derived from the Direct Dispaced-Based Design (DDBD) method recently developed by Priestley et al. [2007] Priestley, M. J. N., Calvi, G. M. and Kowalsky, M. J. 2007. Displacement-Based Seismic Design of Structures, Pavia, , Italy: IUSS Press.  [Google Scholar]. The key aspect of the proposed procedure is the definition of a target displacement profile for the structure. It is assigned by the designer to achieve given performance levels, expressed in terms of maximum displacement of the isolation system and maximum interstory drift. The proposed design procedure has been developed for four different idealized force-displacement relationships, which can describe the cyclic response of a wide variety of isolation systems, including: (i) Lead-Rubber Bearings (LRB); (ii) High-Damping Rubber Bearings (HDRB); (iii) Friction Pendulum Systems (FPS); and (iv) Combinations of lubricated Flat Sliding Bearings (FSB) with different re-centering and/or energy dissipating auxiliary devices. In this article, the background and implementation of the design procedure is presented first. It is followed by the results of validation studies based on nonlinear time-history analyses on different design configurations of base isolated buildings.     

A Modified Capacity Spectrum Method with Direct Calculation of Seismic Intensity of Points on Capacity Curve

A direct methodology for solving the seismic intensity of each point on the capacity curve is proposed. By utilizing the procedure, a continuous curve between the structural response and the seismic intensity, the structural response function, can be easily generated. Unlike previous procedures that search for the performance point of a determined seismic intensity, the proposed methodology easily draws the full curve without iterations. The procedure is applicable to both a smooth design spectrum and an actual response spectrum. Examples indicate the methodology is accurate and fast, and convenient to be combined with existing procedures, such as Modal Pushover Analysis.     

Shake Table Test and Numerical Analysis of a Bridge Model Supported on Elastomeric Pad Bearings

Elastomeric pad bearings are widely applied in short- to medium-span girder bridges in China, with the superstructure restrained by reinforced concrete (RC) shear keys in the transverse direction. Field investigations after the 2008 Wenchuan earthquake reveal that bearing systems had suffered the most serious damage, such as span falling, bearing displaced, and shear key failure, while the piers and foundations underwent minor damage. As part of a major study on damage mechanism and displacement control method for short- to medium-span bridges suffered in Wenchuan earthquake, a 1:4 scale, two-span bridge model supported on elastomeric pad bearings were recently tested on shake tables at Tongji University, Shanghai. The bridge model was subjected to increasing levels of four seismic excitations possessing different spectral characteristics. Two restraint systems with and without the restraint of RC shear keys were tested. A comprehensive analytical modeling of the test systems was also performed using OpenSees. The experimental results confirmed that for the typical bridges on elastomeric pad bearings without RC shear keys, the sliding effect of the elastomeric pad bearings plays an important role in isolation of ground motions and, however, lead to lager bearing displacement that consequently increases the seismic risk of fall of span, especially under earthquakes that contain significant mid-period contents or velocity pulse components. It is suggested from the test results that RC shear keys should be elaborately designed in order to achieve a balance between isolation efficiency and bearing displacement. Good correlation between the analytical and the experimental data indicates that the analytical models for the bearing and RC shear key as well as other modeling assumptions were appropriate.     

Comparison of Numerical and Experimental Seismic Responses of FREI-Supported Un-reinforced Brick Masonry Model Building

Comparative study of numerically and experimentally obtained seismic responses of un-reinforced masonry building supported on in-house designed un-bonded fibre reinforced elastomeric isolator (U-FREI) are presented in this article. The effectiveness of U-FREI is established very clearly in terms of controlled dynamic response of the model building. Experimental studies are carried out on a shake table with elaborate instrumentations for measurement of acceleration and displacements at different floor levels. Numerical study of the model building supported on U-FREI is carried out to compare the results with experimental investigation. Multi-linear pivot hysteretic plasticity model is used to simulate the behavior of FREI, while plate elements are used for brick-masonry walls. Experimentally obtained force-displacement curves of FREI are used for defining the properties of multi-linear model representing FREI. The dynamic responses obtained from the numerical studies are compared with those from experimental investigations. This study indicates that the seismic responses of building supported on U-FREI can be numerically evaluated with quite reasonable accuracy. A good numerical model can be judiciously used at the preliminary design stage, followed by actual testing and construction of the base isolated building.     

Performing Hospitality in Moldova: Ambiguous,Alternative, and Undeveloped Models of National Identity

This paper examines performances of hospitality in everyday life to explore the lived experience of “being Moldovan”. National identity in Moldova can only be understood by reference to the peculiarities of history—to the presence of a neighbouring kin-state (Romania), a multiethnic population, Soviet ideology, and successive efforts at nation-building. The instabilities, contradictions, and ambiguities of national identity are also experienced and interpreted, as they are regularly performed in informal and formal settings. The “hospitality” of Moldovans—performed daily through linguistic code-switching, in practices of buying and selling, in life-cycle celebrations such as weddings, and in the official greeting and welcoming of dignitaries and visiting delegations by folk-costumed performers—is, paradoxically, an important site of this experience of ambiguity. The same set of practices both renders its performers “masters of their own houses”, while at the same time revealing the limits of the metaphor.     

Seismic Behaviors of RC Frame Beam-Column Joints under Acid Rain Circle: A Pilot Experimental Study

This research was carried out to investigate the seismic performance of RC beam-column joints under acid rain circle via comparison of energy dissipation behavior and failure mechanism of joints with different corrosion levels and axial compression ratio. At the initial corrosion level, the strength, ductility, and energy consumption of RC beam-column joints improved slightly; at a later stage, the bearing and deformation capacity decreased as the corrosion rate of steel rebars increased. The test shows that with the increasing of the axial compression ratio, the initial stiffness and ultimate bearing capacity of the joints will increasing if the corrosion levels are the same, but the ductility of that will decrease.