Mine blast vibration response spectrum for structural vulnerability assessment: case study of heritage masonry buildings

Ground-borne vibrations induced by mine blasting are typically of low amplitudes, which are not considered a major concern for modern engineered structures. However, historic structures are often considered more vulnerable due to inadequate knowledge regarding the state of construction materials and structural response. Specifically, the construction materials used might be fragile or have deteriorated to a stage that could be vulnerable to such vibrations. Simplistic rule based on peak ground motion parameter has been adopted worldwide for safety assessment, while the frequency characteristics of vibrations are not taken into account. Further, there is very limited study on response of heritage structures to near-field blasting. This article presents a practical structural vulnerability assessment method for mine blast-induced vibrations. In particular, a design response spectrum model is proposed based on close range measurements of nearby mine blasting, which is compared with an existing design spectrum model for far-field mine blasts and a typical design spectrum model for earthquake actions. The method is illustrated through a case study of heritage masonry buildings in Australia. The unique blast data presented and the generalized methodology would be useful to both structural engineers and blast engineers in considering potential effects of blasting on heritage structures.     

多尺度下中国人口老龄化风险集群的时空格局——Flexible空间扫描计量方法的应用

运用Flexible空间扫描计量方法,对比分析了省、市和县域尺度上的老龄化风险集群的时空格局。发现：老龄化成为全国人口结构转型的主旋律,少子化成为新常态,老龄化区域非均衡加剧,并存多种区域模式;三种尺度识别出的风险集群都集中分布于东南半壁;集群的风险程度与地域范围随时间不断扩大,但集群间的风险差异趋于缩小。总体而言,尺度越小,识别出的集群分布越分散,定位越精确,风险越高,差异越大。针对不同地区的人口-经济发展情况,提出保障生育,发展养老产业,基本公共服务均等化,就地、近城镇化等的老龄化风险应对策略。     

长株潭城市群城镇化进程与水资源利用响应关系研究

采用层次分析法与熵权法相结合的方法,构建长株潭城市群城镇化综合发展水平和水资源开发利用综合潜力评价指标体系及响应关系模型,对2001-2015年间研究区域城镇化发展进程与水资源利用之间的动态过程进行定量研究,分析主要影响因素、变化特征以及两者响应特征。结果表明：长株潭城市群处于快速城镇化和规模扩张阶段,人口城镇化和空间城镇化水平高于经济城镇化和社会城镇化水平,城镇化发展质量有待提升;区域用水负荷逐年增加,虽然水资源利用效率和管理水平稳步提升,但水资源自然禀赋和开发利用程度受区域水文条件的影响显著。在2001、2005、2007、2009、2011年,长株潭区域城镇化的发展在一定程度上受到水资源系统的约束。协调好城镇化与水资源之间的关系,必须改变规模外延扩张模式,以控制水资源总量、有效提高水资源利用效率为目标,减弱水资源系统对城镇化发展的制约,提高水资源保障能力。     

Damage Assessment of Unreinforced Stone Masonry Buildings After the 2010–2011 Canterbury Earthquakes

The sequence of earthquakes that has affected Christchurch and Canterbury since September 2010 has caused damage to a great number of buildings of all construction types. Following post-event damage surveys performed between April 2011 and June 2011, an inventory of the stone masonry buildings in Christchurch and surrounding areas was carried out in order to assemble a database containing the characteristic features of the building stock, as a basis for studying the vulnerability factors that might have influenced the seismic performance of the stone masonry building stock during the Canterbury earthquake sequence. The damage suffered by unreinforced stone masonry buildings is reported and different types of observed failures are described using a specific survey procedure currently in use in Italy. The observed performance of seismic retrofit interventions applied to stone masonry buildings is also described, as an understanding of the seismic response of these interventions is of fundamental importance for assessing the utility of such strengthening techniques when applied to unreinforced stone masonry structures.     

1932年陕西省的霍乱疫情及其社会应对

1932年的霍乱遍及全国,尤以陕西省最为严重。本文主要依据当时的报刊资料对此次霍乱在陕西省的发生、流行以及社会各界的应对进行分析,认为此次陕西省的霍乱疫情蔓延60个县,死亡人数13万以上;呈现出初期远程传播与近程传播同时进行,后期主要以沿交通干线的远程传播为主的特征;至于霍乱疫情的发生有外地传来和本地引发两种可能;社会各界因社会地位、职责等的不同,在应对霍乱的过程中所担当的角色和采取的措施也就各异。     

对费正清中国史观的理性考察

美国的中国学研究始于费正清。在半个多世纪里,他以自己独特的视角审视、考察中国。20世纪50年代,他提出了著名的“冲击－反应”模式,用来作为其解释中西文明冲突的工具。多年来,史学界对此多有争论,对他的中国史观也褒贬不一。对费正清的中国史观以及他提出的“冲击－反应”模式的背景及其实质进行一些理性探讨,有利于更好地了解我们的历史。     

Organising cyber security in Australia and beyond

The Internet is an interconnected network and cyber security requires collective action. How that action is organised has important implications for national security, including the defence against cyber attacks and malicious activities. This article explains the origins and institutionalisation of cyber security in Australia—particularly ‘civilian cyber security’. The authors trace the origin of Australia’s first computer emergency response team and explain how this organisational form spread from the USA. Through it, Australia helped enable international cooperation. Domestically, however, the authors argue that the Australian government has struggled with the delegation, orchestration and abdication of responsibility for civilian cyber security, underinvesting in civilian organisations while overrelying on military and intelligence agencies. The history of this organisational field provides valuable insight into how to improve national policy and operations for cyber security.     

Journeys of resilience: the emotional geographies of refugee women

This article considers the emotional geographies of a highly vulnerable demographic: refugee women. As a marginalised and ontologically fragile group, refugees have developed rich and perceptive insight on space and place, by developing a critical vigilance that reflects forward and back on their life journeys, real and metaphorical. Through participation in a psycho-educational course designed by the author, nine women produced their own images of resilience, in creative exercises that provided ‘landmarks’ of recognition for other participants. Via participation in this temporary ‘community of practice’, therefore, another journey was taken; this article will also consider the epistemology of that itinerary using interdisciplinary insights from geography, cultural studies, cognitive behavioural therapy and gender studies.     

A PROCEDURE FOR COMBINING VERTICAL AND HORIZONTAL SEISMIC ACTION EFFECTS

The vertical component of earthquake ground motion has generally been neglected in the earthquake-resistant design of structures. This is gradually changing due to the increase in near-source records obtained recently, coupled with field observations confirming the possible destructive effect of high vertical vibrations.

In this paper, simple procedures are suggested for assessing the significance of vertical ground motion, indicating when it should be included in the determination of seismic actions on buildings. Proposals are made for the calculation of elastic and inelastic vertical periods of vibration incorporating the effects of vertical and horizontal motion amplitude and the cross-coupling between the two vibration periods. Simplified analysis may then be used to evaluate realistic vertical forces by employing the vertical period of vibration with pertinent spectra without resorting to inelastic dynamic analysis.

Finally, a procedure is suggested for combining vertical and horizontal seismic action effects which accounts for the likelihood of coincidence, or otherwise, of peak response in the two directions.     

SOME DESIGN PRINCIPLES RELEVANT TO TORSIONAL PHENOMENA IN DUCTILE BUILDINGS

Recent studies provided opportunities to review some of the principles, which have been used in the formulations of internationally accepted code-recommendations relevant to the seismic design of ductile buildings also subjected to torsional phenomena. With the progress of this study, features emerged which are considered to have contributed to a better understanding of structural behaviour. Moreover, the identification of deeply embedded fallacies, relevant to ductile response, suggested the introduction of some changes in seismic design strategies, yet not widely known or appreciated. Reasons for necessary re-interpretations of traditional structural properties, together with illustrative examples, demonstrating applications, rather than set code-type rules, are offered.