An Applied Method for General Regional Seismic Loss Assessment—With A Case Study in Los Angeles County

We describe the formulation and application of an integrated general regional seismic loss assessment (RSLA) method for buildings in seismic regions. An efficient method for RSLA is valuable for engineers involved in city planning, risk management, and insurance dealings. In contrast to previously reported methods, the framework presented herein is hazard-based and utilizes a regional rapid seismic hazard deaggregation tool that allows regional assessment to be conducted more efficiently. The proposed technique is implemented as an example to assess general regional seismic loss in Los Angeles County for a ground motion hazard with 10% probability of exceedance in 50 years.     

Sustainability of Highway Bridge Networks Under Seismic Hazard

In order to evaluate the seismic risk of transportation networks, it is necessary to develop a methodology that integrates the probabilities of occurrence of seismic events in a region, the vulnerability of the civil infrastructure, and the consequences of the seismic hazard to the society, environment, and economy. In this article, a framework for the time-variant seismic sustainability and risk assessment of highway bridge networks is presented. The sustainability of the network is quantified in terms of its social, environmental, and economic metrics. These include the expected downtime, expected energy waste and carbon dioxide emissions, and the expected loss. The methodology considers the probability of occurrence of a set of seismic scenarios that reflect the seismic activity of the region. The performance of network links is quantified based on individual bridge performance evaluated through fragility analyses. The sustainability and risk depend on the damage states of both the links and the bridges within the network following an earthquake scenario. The time-variation of the sustainability metrics and risk due to structural deterioration is identified. The approach is illustrated on a transportation network located in Alameda County, California.     

博物馆文物的防震保护研究（三）——陈列文物的地震安全性分析

通过分析博物馆馆藏文物的悬吊、固定、浮放等基本放置形式,探讨了文物的陈列特征及其可能造成的震害因素。综合考察和分析研究了国内外浮放式物体及陈列文物的运动状态,指出陈列文物在地震发生时的主要危害性运动是滑移和倾覆。根据相关浮放物在地震作用下的计算方法、上海博物馆文物的陈列特征及防震设计参数,提出简便实用的浮放式陈列文物稳定性计算模型,编制了适合上海博物馆文物安全性分析的计算程序。并以上海博物馆文物陈列的3类接触材料、4楼中国古代玉器馆的典型陈列文物为试点,计算了陈列文物在地震中遭受破坏的临界值。表明在设防水准的大震和中震情况下,目前陈列现状的绝大多数文物均存在倾覆和滑移安全隐患,但当文物所受到的地震动减小到110gal时可满足陈列安全。     

Group Project Work and Student-centred Active Learning: two different experiences

This article compares two experiences of group-based student projects in a Geographical Information Systems (GIS) degree and in Geography degree modules. The two authors adopted group projects from similar motivations, and used available materials to guide them through this process. Subsequently, they have come to reflect on the experience and to examine the theoretical dimensions of such an approach in more detail. There seems to be a discrepancy between the literature, which emphasises a growing interest in the socio-educational value of group-based and active learning, and the concerns voiced by both students and academics regarding the practical implications of such approaches. Analysis of grades and questionnaires tends to support the literature and belie the criticisms, which the authors see as 'myths', possibly motivated by a defensive attitude to the whole learning process. The conclusions are that, if care is not taken in the design and execution of such projects, then the problems that may ensue can reinforce the 'myths'. However, if carefully and appropriately designed and managed, team-based learning is a valuable experience.     

Undergraduate student perceptions of assessment and feedback practice: fostering agency and dialogue

ABSTRACT

Assessment and feedback practices sit at the heart of education and the student experience. This paper reports on undergraduate perceptions of assessment and feedback in the Department of Geography at King’s College London, UK. Twenty-eight first and second-year students across six focus groups provided comments on their understanding of feedback, their feedback experiences, and what they felt could be improved. It was clear that students desired feedback that would help them improve summative performance, but were unsure of how best to use it and consequently had high expectations that led to dissatisfaction. Particular concern was expressed about marking and feedback consistency, and the inherent variation in practice they experienced. Many comments indicated a lack of student agency, which may reflect the power relations that students find themselves in within their community of practice. Finding ways of fostering agency and improving dialogue over perceptions and expectations are suggested to be important steps in improving assessment and feedback practice, and student satisfaction.     

对加强大学生安全教育的思考

安全是人生中非常重要的一部分,是人们生存发展的保障。安全对于每个人而言都是人生的一门必修课,社会中的每个个体都应纳入安全教育体系中。但是近年来,校园安全事故频频发生,让人震惊。所以在诸多安全问题中,大学生的安全问题凸显出来。大学生的安全意识为何如此淡薄,学校的安全教育存在哪些问题,这已经成为人们关注的焦点。大学生的安全教育不仅是大学生自我保护的需要,也是确保高校秩序稳定,促进国家发展、构建和谐社会的需要。因此,学校必须从多方面加强对大学生的安全教育,落到实处,只有这样才能真正提高大学生的安全意识,促进其身心健康发展。     

Numerical Fragility Analysis of Vertical-Pile-Supported Wharves in the Western United States

This study develops seismic fragility curves for vertical-pile-supported wharves commonly found in the western United States. Nonlinear time-history analyses of a two-dimensional numerical model under two ground motion suites are performed. The results show that the jumbo container cranes increase by 10.8% in the wharf deck drift. By using the experiment-based limit states, the proposed fragility curves demonstrate that, at a PGA of 0.50 g, the probabilities of exceeding slight, moderate, extensive, and complete limit states are approximately 23.0%, 7.0%, 4.0%, and 3.0%, respectively, while at a PGA of 1.00 g, the exceeding probabilities increase to 44.0%, 19.0%, 14.0%, and 11.0%, respectively.     

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.     

Seismic Vulnerability Assessment of an Infilled Reinforced Concrete Frame Structure Designed for Gravity Loads

In the last decades, particular attention has been paid to the seismic vulnerability of existing reinforced concrete buildings designed for gravity loads only. Such buildings, designed before the introduction of capacity design in modern seismic codes, are very common, particularly in seismic prone countries of the Mediterranean area. Due to poor detailing and lacking of capacity design principles, high vulnerability has been highlighted in several past studies. In this article, inadequate seismic response and peculiar damage pattern are investigated by means of shake table tests performed on a 1:2 scaled 3-story infilled prototype. Particular attention is given to the role of beam-column joints and frame-panel interaction. The effectiveness of the EC8-based assessment approach is then evaluated; both linear and nonlinear numerical models, with different levels of sophistication, have been implemented in order to explore their behavioral aspects.     

近十年来中国人口迁移研究及其评价

本文对20世纪90年代以来的中国人口迁移研究进行了总结与评价。文章首先概述了近10年来中国人口迁移研究的主要特点;然后对中国人口迁移研究的主要内容即迁移人口的社会经济特征,人口迁移的空间格局,影响因素,作用,人口迁移政策建议以及人口迁移研究中的理论与方法等方面进行了总结;最后指出了人口迁移研究中存在的问题与未来应该加强研究的领域。