Town of Tornio in November 1898: a rare survey of earthquake damage in Finland

This study investigates the effects of the Fennoscandian earthquake that occurred on 4 November 1898 (GMT) on Tornio in Northern Finland. The extra fire inspection conducted in the town on 21, 22 and 23 November 1898 provided insight into the failures caused by this low-magnitude earthquake. The building stock was of timber with masonry stone components. More than 30 heating units sustained damage. The macroseismic intensity in Tornio is estimated at I = 6 (European Macroseismic Scale).     

Energy demands for seismic design against low‐cycle fatigue

A seismic design procedure that does not take into account the maximum and cumulative plastic deformation demands that a structure is likely to undergo during severe ground motion could lead to unsatisfactory performance. In spite of this, current design procedures do not take into account explicitly the effect of low‐cycle fatigue. Based on the high correlation that exists between the strength reduction factor and the energy demand in earthquake‐resistant structures, simple procedures can be formulated to estimate the cumulative plastic deformation demands for design purposes. Several issues should be addressed during the use of plastic energy within a practical performance‐based seismic design methodology. Copyright © 2006 John Wiley & Sons, Ltd.     

A non‐baseline algorithm for damage locating in flexural structures using dynamic distributed macro‐strain responses

The concept of distributed strain‐sensing techniques has been proposed in our recent research, which was dedicated to utilizing the strain distributions throughout the full or partial areas of structures to detect arbitrary and unforeseen damage. An algorithm not requiring a detailed analytical model is presented for damage locating in flexural structures through the direct use of dynamic responses recorded by distributed long‐gauge strain sensors. The modal macro‐strain vector (MMSV), which has been proven to have a mapping relation with displacement mode shape, can be extracted directly from macro‐strain time‐series data, from which a damage evaluating index can be derived and used as an indicator for locating damage. Numerical examples are simulated to verify the sensitivity and effectiveness of the index in different cases. Furthermore, experimental investigations on a cantilevered beam with various long‐gauge fibre optic sensors placements are carried out to examine the feasibility and applicability of the proposed method. Copyright © 2007 John Wiley & Sons, Ltd.     

A new approach of selecting real input ground motions for seismic design: The most unfavourable real seismic design ground motions

This paper presents a new way of selecting real input ground motions for seismic design and analysis of structures based on a comprehensive method for estimating the damage potential of ground motions, which takes into consideration of various ground motion parameters and structural seismic damage criteria in terms of strength, deformation, hysteretic energy and dual damage of Park & Ang damage index. The proposed comprehensive method fully involves the effects of the intensity, frequency content and duration of ground motions and the dynamic characteristics of structures. Then, the concept of the most unfavourable real seismic design ground motion is introduced. Based on the concept, the most unfavourable real seismic design ground motions for rock, stiff soil, medium soil and soft soil site conditions are selected in terms of three typical period ranges of structures. The selected real strong motion records are suitable for seismic analysis of important structures whose failure or collapse will be avoided at a higher level of confidence during the strong earthquake, as they can cause the greatest damage to structures and thereby result in the highest damage potential from an extended real ground motion database for a given site. In addition, this paper also presents the real input design ground motions with medium damage potential, which can be used for the seismic analysis of structures located at the area with low and moderate seismicity. The most unfavourable real seismic design ground motions are verified by analysing the seismic response of structures. It is concluded that the most unfavourable real seismic design ground motion approach can select the real ground motions that can result in the highest damage potential for a given structure and site condition, and the real ground motions can be mainly used for structures whose failure or collapse will be avoided at a higher level of confidence during the strong earthquake. Copyright © 2007 John Wiley & Sons, Ltd.     

从上海市热岛演变看城市绿化的重要意义

近40年来，上海城市热岛面积扩大了7－8倍，强度增强了一倍，导致了高温灾害的增加。上海热岛的迅速扩张和增强始于20世纪80年代，与上海城市的建设有明显的对应关系。如何合理规划城市建设，减缓热岛效应影响，以保证上海城市的健康和可持续发展，已成为一个迫切需要解决的问题。近几年来显示出的上海中心城区热岛强度减弱趋势表明，城市绿化建设对减缓城市热岛效应具有重要意义。     

不同尺度条件下的土壤侵蚀实验监测及模型研究

土壤侵蚀的实验和监测是获取水土流失资料的重要手段,土壤侵蚀模型研究是水土保持规划、管理的重要内容。本文对点、小区、田间和坡面、流域及区域尺度条件下的土壤侵蚀的实验和监测研究进行了综述,分析了当前国际上实验研究和监测研究的侧重点及其不足;并对当前国际上土壤侵蚀模型的总体发展趋势进行了评述,特别分析了这些模型在全球气候变化背景下的作用;最后对当前土壤侵蚀、试验及检测研究作出展望。     

低渗致密砂岩气田储层损害评价及保护措施

储层孔隙类型、孔隙结构、粘土矿物类型和含量等是造成气层受伤害的潜在因素 ,而外来固相、滤液以及生产或作业压差、生产时间等工程因素也可造成或加重对气层的伤害程度 ,因此 ,低渗致密气田 (藏 )的开发效果在很大程度上依赖于开发技术水平的提高。应用岩心评价实验、时间推移测井、生产测井以及试井等方法 ,评价了河南东濮凹陷白庙、文 2 3等气田低渗致密砂岩储层的敏感性及与外来液的配伍性 ,分析了导致或加重对气层造成伤害的工程因素。在气田开发的全过程中 ,有针对性地制定出对气层进行保护的配套措施 ,减少了对储层的伤害 ,充分发挥了气层的潜力 ,提高了气田的开发效果 ,也为同类气田提供了借鉴。     

断层带爆炸裂隙区范围及裂纹扩展长度的研究

常用求算岩石内爆炸裂隙区半径的计算公式中忽略了冲击波的作用、粉碎区的存在以及爆生气体的准静态作用。醉对该公式进行修正后并引和断层带应力波衰减指数α，并对尖力波损伤后的裂隙区的扩展长度进行分析计算，从而得出：考虑“预报伤”作用的爆炸裂纹长度大于不考虑“预损伤”情况下的裂纹长度。     

海洋风暴形成的一种动力学机制

文中从观测统计学、瞬变涡动能量学和 MM5中尺度数值模拟角度 ,研究了海洋风暴 (爆发性气旋 )形成的气候特征及其可能的动力学机制 ,揭示了一幅爆发性发展的物理图像。结果表明 ,在冷季大气特别是日本以东洋面上大气特有的热力气候背景下 ,通过同海洋风暴过程相联系的涡动热通量 vθ的向极地输送 (- vθ· θm>0 ) ,将季节尺度的时间平均有效位能向瞬变涡旋时间尺度的涡动有效位能转换 ,是海洋风暴形成的主要动力机制。在该过程中转换来的具有最大贡献的涡动有效位能 ,连同具有次大贡献的积云加热制造的涡动有效位能(q3 )一起 ,通过暖异常区 (α >0 )暖湿空气上升运动 (-ω >0 )的斜压转换 (-ωα) ,促使涡动动能增长。同时 ,补充的涡动有效位能又加强了暖异常区的暖湿空气上升运动 ,进而产生积云对流活动及其潜热释放的正反馈过程 ,最终导致涡动动能急剧增长和海洋风暴的形成。海-气潜热输送的作用是在风暴形成初期提供后来积云尺度对流活动及潜热释放的水汽潜力。研究还表明 ,海洋风暴主要发生在冷季月份 1 3 0°E以东的中高纬洋面上 ,这种对特定季节和特定海域的依赖性是大气和海洋气候背景的动力 /热力共同作用的结果