The Numerical Study of Base-Isolated Buildings Under Near-Field and Far-Field Earthquakes

The behavior of base-isolated building frame is investigated with the help of a numerical study for far-field and near-field earthquakes with directivity and fling-step effects. Both design-level and extreme-level earthquakes are considered. Selected response parameters are peak floor displacement, acceleration, base shear, and isolator displacement. Inelastic behavior of base-isolated structure during the earthquake is investigated performing nonlinear time history analysis of a ten-story building frame. This study shows that base isolation is not effective for near-field earthquakes. Even for design-level earthquake, the frame gets significantly into inelastic range for earthquakes with fling-step effect.     

Modelling and Seismic Response Analysis of Italian Code-Conforming Base-Isolated Buildings

ABSTRACT

This paper reports on results of nonlinear analyses performed within the RINTC project on an RC building isolated with different systems (High Damping Rubber Bearings, High Damping Rubber Bearings and Flat Sliding Bearings, Friction Pendulum System) and designed according to the Italian design code. The seismic response has been evaluated under different seismic input levels of two sites with different hazard and by considering two Limit States: Global Collapse and Usability-Preventing Damage. The influence of seismic stoppers and modelling uncertainties is also evaluated. Results permit to compute the implicit collapse risk and to identify critical aspects of current design procedures.     

抗日根据地时期的女性离婚问题——以晋西北(晋绥)高等法院25宗离婚案为中心的考察

中共晋西北抗日民主政权建立后即颁布《晋西北婚姻暂行条例》,对女性离婚权予以法律上的肯定。一批农村妇女以情感、经济等原因向丈夫提出离婚,根据地婚姻观念或离婚现象呈现出与以往不同的景观。由于离婚案件频频发生,影响了中共抗战大局,中共中央于1943年发表关于各抗日根据地妇女工作方针的四三决定,修正过去激进的婚姻变革路线,以将妇女关注的重点由婚姻问题转向生产建设并缓解根据地两性之间日益紧张的矛盾。这种策略性的政策转变引起法院对待离婚案件的处理发生演变,即不同时期性质相同或相近之案件,其审理结果迥然相异。这亦说明婚姻变革须立足于现实的客观实际。     

Evaluation of IBC Equivalent Static Procedure for Base Shear Distribution of Seismic Isolated Structures

It has been pointed out that the static lateral response procedure for base isolated structures presented in IBC somewhat overestimates the seismic story force [Lashkari and Kircher, 1993 Lashkari, B. and Kircher, C. A. . Evaluation of SEAOC/UBC analysis procedures, Part 1: Stiff superstructure. Proceedings of a Seminar on Seismic Isolation, Passive Energy Dissipation and Active Control. Redwood City, California. ATC Report 17-1.  [Google Scholar]; Constantinou et al., 1993 Constantinou, M. C., Winters, C. W. and Theodossiou, D. . Evaluation of SEAOC and UBC analysis procedures, Part 2: Flexible Superstructure. Proceedings of a Seminar on Seismic Isolation, Passive Energy Dissipation and Active Control. Redwood City, California. ATC Report 17-1.  [Google Scholar]]. In this article IBC equivalent static method for base shear distribution of seismic isolated structures is evaluated. For this purpose one-story to six-story building models are designed according to equivalent lateral response procedure for different elastomeric isolation systems. The results of equivalent lateral response procedure in parameters such as base shear and vertical distribution of base shear are compared with results obtained from dynamic nonlinear analysis and the efficiency and limitations of its application are investigated. In general, the results of equivalent lateral response procedure in base shears are acceptable within the scope of this procedure, but the proposed triangular distribution of base shear is somewhat conservative. So a new formulation for vertical distribution of base shear is proposed which results in a more realistic distribution of shear over the height of isolated buildings. The accuracy of the new formulation is examined by comparing the resulting responses obtained from this study with those calculated by nonlinear time history analysis.     

Optimal Control of Accelerations in a Base-Isolated Building using Magneto-Rheological Dampers and Genetic Algorithms

This article presents a numerical study aimed at improving effectiveness of the isolation system of an actual building by adding magneto-rheological (MR) dampers that act in parallel to the existing rubber bearings (RB). The building itself is modeled with uniaxial elastic elements. Additional elements that include the RBs and the MR dampers are added at the base of the building and two different genetic algorithms are used to optimize operation of the MR dampers. Maximum acceleration and relative displacement at the top of the building are taken as the variables to be minimized. Records of destructive earthquakes are used as input. A comparison is made between the building responses with RB and the one with the additional control system.     

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.     

Seismic Performance to Emergency Centers,Communication and Hospital Facilities Subjected to Nepal Earthquakes, 2015

Emergency centers, communication systems, and hospitals are essential infrastructures for emergency rescue and subsequent reconstruction activities. An investigation into the Nepal 2015 earthquake sequences found that the visited government offices were functioning normally 40 days after the main shock; that the local media failed to coordinate with the entire society at the beginning, but mobile phone-based communication recovered quickly; and that the hospitals in high-intensity areas were badly damaged as a result of improper design and adverse site configuration. Recommendations are proposed to enhance the aseismic capacity of structural and non-structural components using earthquake early warning and base isolation.     

谈新四军及华中抗日根据地的报刊精神

新四军及华中抗日根据地报刊,在中国共产党的正确领导下,为新四军及华中抗日根据地的创建和发展,为抗战全面胜利作出了历史性贡献。新四军及华中抗日根据地的报刊精神主要体现在政治坚定、导向鲜明的党性原则;艰苦创业、乐于奉献的革命传统;贴近生活、通俗生动的求实风格三个方面。     

论华中抗日根据地的优抚工作

华中抗日根据地十分注重对退伍、伤残军人和抗属的优抚工作:制定优抚法律、政策,设立社会保障机构,开展优抚政策的宣传教育,组织拜年和节日慰问活动,帮助抗属解决生产生活问题,减轻各种税费,抚恤烈士,安置伤残、退伍军人。优抚经费既包括政府拨款,也包括民间筹集。华中抗日根据地优抚工作的特点是:物质与精神保障相结合;适度保障,维持基本生活;对国民党军队一视同仁;把保障与鼓励自力更生相结合。优抚工作对于动员民众参军参战,密切党政军民关系,配合统一战线的开展等方面都具有重要的意义。     

A Base Isolation System for Developing Countries Using Discarded Tyres Filled with Elastomeric Recycled Materials

This article studies the performance of economic base isolators using tyres filled with elastomeric recycled materials. The research was conducted to analyze base isolators to be used in developing nations, where the application of conventional elastomeric rubber bearings due to economic reasons is limited.

The tested isolators are made of kart tyres filled with different recycled elastomeric materials and aggregates. Dynamic and static tests proved acceptable vertical to horizontal stiffness ratio of the bearings and shake table tests showed an excellent enhancement of the base isolated structural response compared to the corresponding fixed base structure.