Impact of Modification on Ground Motion Characteristics and Geotechnical Seismic Analyses for a California Site

The impact of different modification techniques on ground motion characteristics and results of seismic geotechnical analyses is investigated for a site in California. Twenty-eight motions were selected and scaled and also modified using both time domain (TD) and frequency domain (FD) techniques. PGV and PGD of the TD-modified motions are found to be larger than their FD-modified counterparts, but slightly less than the scaled ground motion characteristics. Cyclic stress ratios and amplification factors are similar for all sets of motions. Newmark-type slope displacements caused by the scaled and modified ground motions are similar (within 25%) for a variety of sliding masses.     

Have you heard the one about the disappearing ice? Recasting Arctic geopolitics

This article unpacks the discourse of Arctic geopolitics evident in the space-making practices of a wide variety of actors and institutions, offering an exploration of the ways in which the Arctic is emerging as a space of and for geopolitics. Tracing the well-aired story of Arctic geopolitics through neo-realist readings of climate change, the melting of polar ice, increasing competition for resources and so on, two kinds of spatial ordering are identified as being entwined in orthodox Arctic geopolitics. The first has to do with Arctic space as such, and its open, indeterminate nature in particular. The perceived openness of Arctic space enables it to become a space of masculinist fantasy and adventure, which is mirrored in contemporary accounts of Arctic geopolitics. It is suggested that this is entwined with and nourishes the second ordering of Arctic space in terms of state-building and international relations. The working out of these spatial orderings in recent interventions in Arctic geopolitics is explored via three examples (two Arctic exhibitions in London, the Russian Polar expedition of 2007 and ’sovereignty patrols’ by Canadian Rangers). In conclusion, the article presents avenues for further critical research on Arctic geopolitics that emphasizes embodiment, the resolutely (trans)local, and a commitment to the everyday.     

Seismic Behavior of L-Shaped RC Squat Walls under Various Lateral Loading Directions

Considerable progress has been made on the research of non-rectangular reinforced concrete (RC) squat walls over the past decades. However, the experimental data of L-shaped RC squat walls remain limited, especially for their seismic behaviors under non-principal bending actions. This paper presents an experimental and numerical investigation on L-shaped RC squat structural walls with an emphasis on how varying the directions of lateral cyclic loading influences the seismic responses of these walls. Four L-shaped specimens are tested under lateral cyclic displacements and low levels of axial compression The variables are axial loads and lateral loading directions. The performance of specimens is discussed in terms of cracking patterns, failure mechanisms, hysteretic responses, deformation components and strain profiles. Furthermore, three-dimensional finite element models are developed to supplement the experimental results. The direction of lateral loading is found to have a significant effect on the peak shear strength of L-shaped RC squat walls.     

《馆藏文物防震规范》关键技术——防震安全设计研究

《馆藏文物防震规范》WW/T 0069-2015,基于馆藏文物防震安全提出馆舍、展陈和文物全系统防震安全理念、设计方法和具体措施。本研究针对馆藏文物防震设计方法、适用范围、展柜及文物安全性判别等关键技术问题展开研究。首先,提出了"地震波+馆舍+展柜+文物"的全过程全系统防震设计理念;其次,针对浮放展柜及文物,进行地震作用下安全性分析研究;第三,与Getty博物馆研究成果对比,验证本研究理论的正确性与可靠性。分析得出:文物防震安全与文物高宽比、支撑接触面摩擦系数、安放处加速度峰值等因素有关;引入了抗滑动安全系数和抗倾覆安全系数进行设计,可充分保证文物安全性。     

Social memory and ethnic identity: Ancient Greek drama performances as commemorative ceremonies

This paper is an ethnographic account of ancient Greek drama performances that take place in contemporary Greece. The material presented here is part of the data that were collected, mainly through participant observation, interviews and newspapers, during 1997 and 1998 in Athens. The paper illuminates an aspect of modern ancient drama performances that has not been taken into account until today: it treats them as commemorative ceremonies that produce, reproduce, and transmit social memory. The interrelation and interdependence between social memory and ethnic identity construction processes are analyzed and is shown that ancient drama performances, due to specific characteristics, constitute something more than mere theatrical events (as they are defined within the Western tradition). These performances, which convey, sustain, and transmit perceptions of a glorious culture of the past, become, for their creators and spectators, as members of an ethnic group, occasions for consciously remembering their ethnic past, and coming, in a way, to a "mythical identification" with it.     

History,tradition, and memory among the Basques

This article explores the historical commemoration, the Alarde of the Spanish-Basque town of Hondarribia, re-enacted for almost 400 years. It is a social account of the past portrayed through a history of local militarism and a history of commemorative performance. Since 1996, controversy has divided local inhabitants concerning wider female-inclusion in the male-dominated event, separating the town into factions, traditionalists (asserting traditions remain the same) and feminists (advocating broader female involvement). Theoretical concerns include examining traditions and their gradual transformations over time, rather than as episodic change; that interpreting the past can be competitive over rights of belonging; that history may be influenced by different agencies of gender, kin ties, memory, politics, and social experience; that people do not purposefully ignore the passage of time but may be protecting communal harmony; that commemorative rites are more than embodied performances; and that history can be a multiple, contested, and lived experience.     

SHAPE MEMORY ALLOYS IN SEISMIC RESISTANT DESIGN AND RETROFIT: A CRITICAL REVIEW OF THEIR POTENTIAL AND LIMITATIONS

Shape memory alloys (SMAs) are a class of materials that have unique properties, including Young's modulus-temperature relations, shape memory effects, superelastic effects, and high damping characteristics. These unique properties, which have led to numerous applications in the biomedical and aerospace industries, are currently being evaluated for applications in the area of seismic resistant design and retrofit. This paper provides a critical review of the state-of-the-art in the use of shape memory alloys for applications in seismic resistant design. The paper reviews the general characteristics of shape memory alloys and highlights the factors affecting their properties. A review of current studies show that the superelastic and high-damping characteristics of SMAs result in applications in bridges and buildings that show significant promise. The barriers to the expanded use of SMAs include the high cost, lack of clear understanding of thermo-mechanical processing, dependency of properties on temperature, and difficulty in machining.     

FRAGILITY OF STANDARD INDUSTRIAL STRUCTURES BY A RESPONSE SURFACE BASED METHOD

National and international regulatory standards require industrial risk assessment, taking into account natural hazards including earthquakes, in the framework of Quantitative Risk Analysis (QRA). Seismic fragility analysis of industrial components may be carried out similarly as what has been done for buildings, even though some peculiar aspects require the development of specific tools. In the present paper a contribution to the definition of a rational procedure for seismic vulnerability assessment of standardised industrial constructions in a probabilistic framework is given. The method covers a range of components of the same structural type. Seismic reliability formulation for structures is used. Both seismic capacity and demand are considered probabilistic with the latter assessed by dynamic analyses. The application example refers to shell elephant foot buckling of unanchored sliding tanks. A regression-based method is applied to relate fragility curves to parameters varying in the domain of variables for structural design.     

Physical and Numerical Approaches for the Optimal Insertion of Seismic Viscous Dampers in Shear-Type Structures

This article presents the results of an exhaustive parametric analysis which compares the performances offered by various systems (which lead to both classical and non classical damping matrices) of added viscous dampers in shear-type structures. The aim of the research work here presented is the identification of the system of added viscous dampers which maximizes the dissipative properties under an equal “total size” constraint. The choice of the systems of added viscous dampers considered in the comparison is carried out both using a numerical approach (based upon the use of genetic algorithms) and a physically based approach (based upon the properties of classically damped systems). The comparison is carried out through the numerical evaluation of the dynamic response of representative shear-type structures to both stochastic and recorded earthquake inputs. The results obtained using both approaches indicate that a damping system based upon the mass proportional damping component of the Rayleigh viscous damping matrix (referred to as MPD system) is capable of optimizing simultaneously a number of different performance indexes, providing the best “overall” damping performances. The MPD system is characterised by viscous dampers (a) which connect each floor to a fixed point and (b) which are sized proportionally to the corresponding floor mass.     

Seismic Resistance Evaluation of Unreinforced Masonry Buildings

The article presents seismic resistance evaluation study of unreinforced brick masonry buildings. The study was carried out as part of the Ph.D. research work of the first author. As part of the study, in addition to the standard laboratory tests, a dynamic field test was carried out on single-story, single-room unreinforced masonry structure. The model structure was tested in actual ground conditions against simulated earthquake vibrations produced through controlled explosions, especially designed for this purpose. Based on masonry properties accrued from lab and field tests, finite element models of the brickwork system were also studied. Finally, the software named, “Shear Damage Index (SDI),” developed as part of this study, was used to plot contours of shear demand (shear stress) to shear capacity (shear strength) ratio on the numerical model and hence to identify potential weak zones in the model for possible strengthening of those locations.