Internal borders and external factors in outermost island regions. The case of the Canary Islands

The defining element of island regions is their isolation, the separation of the islands from the mainland; there is an inherent notion of natural border. This condition has preserved ecosystems and protected against outside threats, stimulating ‘coevolution’ between man and the environment, a fundamental ingredient of sustainability. But insularity also means the evident added costs of access to markets which, together with territorial limits and the scarcity of basic resources, especially on small islands, hinders their socioeconomic development. These costs are even greater in the case of outlying islands, which suffer from a ‘double insularity’ in the form of both external and internal borders. For this reason, it is common for governments to establish various forms of support, from tax exemptions to the creation of permanent aid funds, like those implemented by the European Union for the outermost regions. This article discusses these aspects in the case of the Canary Islands, an example of a European outermost island region. The findings show that the support measures have not always been favourable for all the islands.     

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.     

南唐二陵墓室彩画上滋生藻类、苔藓与霉菌的种类鉴定

南唐二陵墓室彩画上滋生大面积的苔藓、藻类、霉菌,使原有精美鲜艳的彩画被严重遮盖腐蚀。为此,对南唐二陵墓室彩画上滋生的藻类、苔藓与霉菌进行分离纯化,通过菌落形态观察与显微形态观察,对其表面滋生的藻类、苔藓与霉菌进行了初步种类鉴定。鉴定结果表明,确定霉菌为黑根霉(R. nigricans)、亮白曲霉(A.candidus)、青霉 (P.echinulatum Raper)等;苔藓为墙藓属(Totula sp)、毛口藓属(Trichostomum Bruch);藻类为鞘丝藻属(Lyngbya)。鉴定结果可为进一步的防藻、防霉技术研究和墓室彩画的现场保护研究提供科学依据。     

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.     

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.     

Choices and Criteria for Seismic Strengthening

Risk assessment is affected by large uncertainties, depending on hazard, structure, damage, and loss analysis. Crucial problems and choices may refer to: (a) hazard parameters, including the definition of appropriate ground motion levels and of their probability to occur; (b) level of knowledge about materials, geometry, detailing; (c) assessed damage and failure modes; and (d) resulting potential for step changes in performances.

The cost of attaining a high level of knowledge may significantly reduce the remaining resources, it is therefore important to favor resilient solutions with a creative adoption of appropriate strengthening strategies.

In this framework, this article discusses the possible criteria for the mitigation of seismic risk and some of the alternative choices that may be adopted for strengthening, with reference to:

(a)?the modification of damage and collapse modes strengthening individual elements or locallyincreasing the deformation capacity;

(b)?the insertion of additional systems resisting to horizontal actions;

(c)?the introduction of base isolation, with the objective of capacity-protecting the existingstructure;

(d)?the reduction of displacement demand by added damping or introducing tuned masssystems.

Alternative strengthening choices lead to different protection levels and imply different performances that are, in general, represented by non linear or step functions of a cost parameter of the intervention. From these considerations, conceptual “structure driven” strengthening criteria, based on a logical use of resources, are discussed.     

Friction Model for Sliding Bearings under Seismic Excitation

In this article, an experimentally validated model is proposed in order to take into account main sources of performance degradation that could be experienced by friction-based devices during a seismic event. Particular attention is dedicated to the degradation of friction characteristics due to repetition of cycles and consequent temperature rise. This effect can be responsible for overestimate of the dissipation capacity of the device. The proposed model of frictional behavior is suitable for immediate implementation in generalized structural analysis codes and provides an important design tool for realistic assessment of the seismic response of structures equipped with friction-based isolators.