Wireless Measurement System for Ground-borne Vibration and Vibration Amplifications in Buildings

The environmental impact on residents of buildings, such as adverse effect on sleep and physical discomfort is caused by ground-borne vibration sources such as rail transit systems, road traffic, construction sites, and industrial plants. To estimate the impact of these vibrations on the residents, it is necessary to measure the tri-axial vibrations in the vertical and horizontal directions of the buildings as specified in the international standard regulated by ISO 2631-2:2003. A wireless measurement system for simple and accurate measurement of building vibration was developed. Five wireless vibration measurement devices (installed together with a data recorder in the building) are controlled simultaneously by an outdoor mobile PC or a laboratory PC via wireless local area network and an Internet connection. It sends the vibration acceleration waveforms recorded in buildings over the wider internet communication system to the laboratory PC. The wireless measurement system was used for measuring vibration in two- and three-story detached houses of wooden or steel construction. The impact on the residents may be caused by the vibration amplifications associated with building structural resonances. The vibration amplifications in 120 houses were evaluated as ratios and level differences in 1/3 octave band vibration accelerations measured at the ground near the substructure and floors.     

Spectral story drift demand analysis for building structures during the 1999 Chi‐Chi Taiwan earthquake

Abstract

The 921 Chi‐Chi earthquake caused a very significant number of building collapses and damage of various degrees. Many collapsed buildings had pedestrian corridors and open fronts on the ground floors. Using a modified modal participation factor and the generalized shape function computed from the nonlinear push over analysis, story drift demands imposed on soft first story building systems are studied in this paper. Generalized shape functions are constructed from the nonlinear static push over analysis of shear buildings having specific distributions of story stiffness and strength. Nonlinear response spectrum analyses were performed on the ground acceleration recorded from 51 sites located in the Taipei Basin and 62 sites in the Taichung Region. Analytical results indicate that soft first story buildings are likely to have story drift demands significantly greater than regular buildings of short fundamental period. Results of the nonlinear dynamic analysis of a 6‐story structure indicate that the maximum story drift demand can be satisfactorily predicted by the story spectral drift constructed from the generalized shape functions.     

楼房拆除中控制爆破措施的综合运用

1# 和 2 # 两幢框架结构楼房成一直线排列 ,相距 7m。因环境条件所限 ,只能纵向向西顺序倾倒。 2 # 楼西端的楼梯间与主楼之间有施工缝相隔 ,成为具有较大高宽比的独立结构。根据被拆除物的不同结构特点 ,采用不同的控制爆破措施。 1# 楼的箱形基础与地上结构同时爆破拆除。通过选择合理的爆破切口高度和适宜的延迟时间 ,1# 楼和 2 # 楼主体朝预定的方向顺序倾倒 ,而楼梯间倾倒在 1# 楼的爆堆上。     

有机玻璃-空气隔层结构对水下爆炸能量输出的影响

采用“弯矩逐段解体法”沿建筑物的对角线方向爆破的方法 ,成功地拆除了一栋七层框架结构大楼。文中对沿对角线方向倾倒与平行于梁的方向倾倒的受力情况进行了对比 ,并对沿对角线方向倾倒时梁的受力情况进行了详细分析。此外 ,对爆破参数和网路设计以及安全技术作了论述。     

Petrography as an essential complementary method in forensic assessment of concrete deterioration: Two case studies

Concrete damage is most often first assessed using traditional methods, e.g., strength testing (compressive, tensile), total porosity from water uptake, water infiltration depth, cement/aggregate ratio and chloride content. While traditional methods may produce useful results bearing clues to resolve the problem, in some cases they do not, and can even be harmful to the parties involved. This paper describes two such cases where traditional methods provided false or inadequate results, putting liability with the wrong party. Both cases illustrate that petrography is an indispensable tool in the forensic assessment of concrete.In the first case, a building and construction contractor was held liable for the damage to a newly built sedimentation basin, according to the results of an initial assessment “of poor quality concrete”. A second assessment using impregnation–fluorescence petrography combined with detailed geochemical analysis revealed that instead the concrete was of normal constitution and compliant with specification, and that the damage was due to the application of urea, releasing the contractor from his conviction.The second case deals with pre-fabricated foundation piles that cracked upon pile-driving. The pile-driving contractor was blamed for the damage, allegedly from too much driving energy in combination with a worn-out wooden baffle. While the compressive strength of the concrete was normal, the tensile strength was found to be less than half of the expected value. Thin section petrography revealed poor adhesion of aggregate to the surrounding paste, confirming field observations. This could be attributed to “liquefaction and water expulsion” at an early stage of production when the piles still were under the care of the manufacturer.     

Failures of structures during the October 23, 2011 Tabanlı (Van) and November 9, 2011 Edremit (Van) earthquakes in Turkey

The October 23, 2011 Tabanlı and November 9, 2011 earthquakes that hit Tabanlı and Edremit districts of Van province in Turkey and their impacts on different types of structures are studied in this paper. According to United States Geological Survey (USGS), the magnitudes of these earthquakes, which caused partial or total collapse of numerous buildings and more than 600 casualties, were 7.1 and 5.6, respectively. Other than negatively impacting all aspects of daily life, the earthquakes remarkably disrupted the economical activities in the area. This paper summarizes the seismological characteristics of the affected region, the general characteristics of the strong ground motion and the types of structural damage observed during site investigations. Emphasis is given to the failures and seismic performance of different types of structures, through detailed explanation of damage mechanisms. The structural damage levels are observed to be directly related to the extent of irregularities of the structural system, level of the insufficient quality in the workmanship, and usage of inadequate building materials. It was also clearly observed that if a minimum amount of engineering attention had been paid during the construction stages, and the requirements of design and construction codes had been satisfied, most of the existing buildings could have sustained the earthquakes without considerable damage.     

多栋楼房同时爆破拆除

长春市伪满皇宫博物院门前的4栋七层楼房采用了定向和逐段解体的爆破方法同时拆除,降低了楼体坍塌时对地面的冲击强度。此方案在爆破拆除过程中,不但考虑了每栋楼之间是相互影响的,而且也是可以相互利用的,因此采用了交叉延时爆破,使每栋楼房在倒塌落地前可以互相阻挡爆破飞散物。此外,爆前预拆除全部由机械来完成,加快了施工进度。这些技术措施确保了多栋楼房同时爆破拆除圆满成功。     

May 1, 2003 Turkey—Bingöl earthquake: damage in reinforced concrete structures

On 01.05.2003 an earthquake of magnitude 6.4 occurred in Eastern Anatolia causing damage to hundreds of reinforced concrete (RC) and masonry buildings. Inspections carried out in the disaster area have given an idea about damage types and quality of concrete used in these buildings. The most interesting point is that lots of school buildings constructed within the last 5–6 years were damaged heavily. Poor concrete quality and poor reinforcement detailing caused damage in these structures. Although many are thought to be constructed according to renewed earthquake code in 1997, it is observed that in construction of collapsed or damaged buildings, code requirements and technical issues are ignored. Some tests after the earthquake showed that the quality of concrete in the damaged buildings is poorer than the one assumed in building projects. In this paper, reasons why the buildings were damaged in the 01.05.2003 earthquake in Bingöl, Turkey are given. Some suggestions are made to prevent such disasters in the future.     

Conceptual basics and tools to assess the multi hazard vulnerability of existing buildings

The European Macroseismic Scale 1998 – (EMS 98) is an instrument for the natural hazard of earthquakes, which allows the explanation of observed differences in the behaviour of the prevailing construction types by introducing and implementing vulnerability classes. The EMS 98 enables also the identification of purely empirically justified ranges of scatter. The basic methodology is also applicable to other natural hazards such as flood, tsunami and wind. This permits the development of a unified methodology for the consideration of building vulnerability in the sense of a multi‐hazard approach. For the first time, a vulnerability‐oriented instrument is available to evaluate a building stock for different natural hazards according to criteria that have been standardised in terms of engineering. The multi‐hazard vulnerability with its possible scatters is examined and visualized on real building inventories. With the concept of ”LEGOisation“ the existing buildings, a novel approach is presented to allow the sub‐structuring of buildings into storeys (including roof, basement and floors) to further development of the classification towards specific damage characteristics and local vulnerability. A still to be developed ”Conceptual Simulation Tool“ is described as an outlook. This uses the tools and methods developed to simulate damage and losses as a result of various natural hazards and their sequences.     

淤泥质粘土条件下高层大厦基坑支撑爆破拆除

介绍了特殊地质条件下高层大厦地下室基坑砼支撑围檩的爆破拆除技术.考虑爆破体与地下室底板、支护桩和钢立柱的关系,采用特殊的施工工艺、合理的爆破参数和起爆网路,并在爆体周围搭建似封闭式的防护棚.着重分析了网路的安全性和可靠性.     

Investigation and remediation of houses affected by radon phenomena connected with earlier exploration of silver and uranium ore

The sources of gamma radiation inside buildings affected by earlier silver and uranium mining activities are discussed. Possibilities how to reduce gamma dose rates from building materials were studied on several houses located in the old mining town Jáchymov. Results of the efficiency analysis are presented. Experience obtained up to now indicates that it is almost impossible to reduce the gamma dose rates in such buildings to the level corresponding with the natural background, because some of the gamma radiation sources cannot be completely removed from the building structures.     

Solid and timber construction in residential buildings / Massiv‐ und Holzbau bei Wohngebäuden

In the context of a comprehensive analysis of the current situation in Germany’s residential sector as regards construction costs and developments in these, the Arbeitsgemeinschaft für zeitgemäßes Bauen e.V. (ARGE) undertook a specific study to investigate the use of the main materials for building walls (using both solid and timber construction methods) in residential buildings. In order to obtain comparable data, two buildings typical of the residential sector were modelled: an apartment block and a detached house. These reflect the current building situation in Germany. It should be noted that for both multi‐storey buildings and detached homes, if we look at the median cost, it is more economical to use masonry for the basic structure than timber. The cost advantage of the solid construction method over the timber method for detached houses is 4 %, and the median advantage for apartment blocks is between 4.7 and 6 %. The studies we used in our assessment of the sustainability of the building materials used (for example from TU Darmstadt) conclude that both construction methods (solid and timber) are comparable in terms of the ‘ecological balance sheet’ results achieved over their entire life cycles and occupancy phases.     

高大凹型结构楼房爆破后坐分析

为了避免和预防楼房爆破拆除出现后坐而造成的危害,根据建筑物爆破拆除过程中常出现的后坐现象,总结出3种基本形式:楼房倾而不覆;楼房虽倾覆,但解体和爆破效果差;楼房倾覆,但后坐严重,破坏了需要保护的建(构)筑物。结合高大凹型结构、重心偏离中心线楼房的爆破案例,对楼房爆破拆除的后坐现象进行了分析,产生后坐的原因有结构分析不彻底、延时时间设置不当等等。为此,提出了特殊切口、降低局部强度、控制楼房塌落倾斜加速度、改变起爆方式、减小支撑体与紧邻前部的延时时间等相应的解决措施。爆破案例的爆破效果说明了预防楼房爆破后坐必须从爆破方案设计开始,对整个爆破过程进行周密的预见性分析。分析结果对今后类似楼房的爆破拆除具有借鉴意义。     

Forensic analysis of the evolution of damages to buildings constructed in a mining area (Part II)

This study is framed within a larger project in which the goal is to conduct a detailed forensic analysis of the evolution over time of the damage caused to a number of buildings in an industrial area located just outside of La Unión (Murcia, Spain), following a land failure that occurred in 1998. First, a detailed mapping of the cracks that appeared in the affected buildings was carried out, determining their most representative characteristics and their evolution over time (López Gayarre et al. [1]). This article describes the work performed in the second phase of the study in which the evolution of the most significant cracks found in the buildings during the first phase is quantified using biaxial extensometric units and inclinometers.An analysis was performed, comparing the data obtained in June 2005 with that obtained in November 2008. The data recorded annually was also analyzed. In addition, we started the studies by calculating the most significant absolute values in an effort to determine the area inside which there is still some activity in the subsoil. The objective of this article is to quantify the analysis of the major cracks in the buildings affected by ground subsidence.The results obtained confirm the findings established during the first phase of this study. The damages are a result of constructing the buildings on a potentially hazardous area in which a sinking of the ground takes place due to a mining subsidence phenomenon.     

基础刚度对高层建筑抗震性能影响研究

该文建立了可以同时考虑基础刚度与地下室周边土体约束影响的结构分析模型,给出了确定单桩竖向刚度的原则与计算周边土体弹簧刚度的方法。通过对21层、32层和43层剪力墙结构在7条地震波作用下的时程分析,考察基础刚度和地下室周边土体弹簧刚度对结构抗震性能的影响。计算结果表明,考虑基础刚度后,结构自振周期加长,层间位移角增大,楼层水平剪力与倾覆力矩略有减小,地下室外墙土体反力显著增大,桩顶反力变化幅度减小。对于矩形平面的建筑,考虑基础刚度对短边方向的影响远大于对长边方向的影响。随着建筑高度与高宽比增加,考虑基础刚度引起的各种结构效应随之增大。由于高层建筑的高宽比大,侧向刚度起控制作用,基础刚度对结构抗震性能的影响值得高度关注。     

多栋楼房同时爆破拆除

长春市伪满皇宫博物院门前的4栋七层楼房采用了定向和逐段解体的爆破方法同时拆除,降低了楼体坍塌时对地面的冲击强度。此方案在爆破拆除过程中,不但考虑了每栋楼之间是相互影响的,而且也是可以相互利用的,因此采用了交叉延时爆破,使每栋楼房在倒塌落地前可以互相阻挡爆破飞散物。此外,爆前预拆除全部由机械来完成,加快了施工进度。这些技术措施确保了多栋楼房同时爆破拆除圆满成功。     

Assessment of subsidence in Delhi NCR due to groundwater depletion using TerraSAR-X and persistent scatterers interferometry

Currently, high-resolution SAR data is available from different satellites. These datasets have been proved to be a strong source to monitor land subsidence. This paper aims to use high-resolution Persistent Scatterers Interferometry (PSI) to estimate the urban subsidence in Delhi NCR. TerraSAR-X images in 68 numbers spread over a period of 26 months during September 2011 – September 2013 have been used to assess the land surface subsidence. The study area is covered with large infrastructure projects such as railway lines, bridges, highways, metro bridges and tunnels. The resultant surface subsidence has been compared with the groundwater table data and it appears that most of the subsidence has been induced by the over-exploitation of groundwater in the area. In some areas, we can clearly see that the rapid construction activities contributing to the surface subsidence phenomenon. Development of a new construction project required groundwater to be used in the activity which impacts the groundwater table. This deterioration of the groundwater table has led to the land subsidence. The study suggests that there is an urgent need to address the issue of groundwater exploitation in the affected areas to check the current phenomenon of subsidence. This is a distinctive work carried out over the study area.     

社区地震安全韧性评估系统及应用示范

高烈度地区重要建筑往往采用RC框架-剪力墙结构体系,采用隔震技术设计该类建筑,满足《建设工程抗震管理条例》中规定的设防地震下正常使用要求,甚至满足罕遇地震下的高韧性目标需求,成为了该类结构设计的重点难题。该研究以一8度区的RC框架-剪力墙工程为例,对该结构的抗震方案展开了设防和罕遇地震下的地震韧性评价。在此基础上,针对隔震结构提出了3种上部结构设计理念,并设计了3个隔震案例,进行了设防和罕遇地震下的韧性评价。分析结果表明：传统抗震结构在设防地震下无法满足正常使用需求,抗震韧性等级仅为一星;按降一度贴限设计确定隔震上部结构截面且按降一度确定上部结构配筋时,设防地震下需3.1 d的修复时间才能恢复正常使用功能,罕遇地震下的抗震韧性等级为二星;按降半度贴限设计确定上部结构截面,且按降一度确定上部结构配筋时,建筑功能可基本不中断,满足正常使用需求,但罕遇地震下的抗震韧性等级仍为二星;按不降度贴限设计确定上部结构截面且按降一度确定上部结构配筋时,建筑功能完全不中断,满足正常使用要求,罕遇地震下可达到韧性三星。研究的相关成果可为高烈度地区RC框架-剪力墙结构的隔震韧性设计的深入研究提供参考。     

核爆冲击波作用下高层建筑倾覆机理分析

我国高层建筑下部大多建造附建人防地下室,上部结构与人防地下室的连接比较牢固。核爆冲击波作用下,高层建筑可能会发生很大的变形、破坏甚至倒塌。在此过程中,可能会对附建于其下的人防地下室产生较大的倾覆作用,进而导致地下室发生较大的倾覆反应并丧失其防护功能。该文研究的重点是高层建筑附建人防地下室的倾覆问题。该问题涉及结构-基础-土的相互作用,需考虑材料非线性、接触非线性、材料性能的应变率相关性及土体体积压缩硬化等特征。介绍作者近年来在这方面的一些研究成果,主要有:利用动力有限元软件LS-DYNA分析了核爆冲击波作用下混凝土空心砌块墙的动力响应,利用大型通用有限元软件MSC.MARC和基于MARC平台开发的钢筋混凝土杆系纤维模型、土的修正D-P模型和桩土相互作用弹簧模型子程序,建立上部结构-地下室-土(桩)系统整体计算模型,对核爆冲击波作用下高层建筑附建人防地下室的倾覆进行了数值计算。算例计算结果表明:核爆冲击波作用下,天然地基高层剪力墙结构附建人防地下室的最大转角可能大于3°―5°,甚至完全倾覆,进而丧失其战时防护功能;桩基础可显著降低高层剪力墙结构附建人防地下室的倾覆反应,可作为高层建筑附建人防地下室抗倾覆的措施。在满足正常设计要求基础上,桩长、桩距和桩径在一定范围内的变化对地下室的倾覆反应影响不大,可以忽略。     

一种新型分缝耗能砌体填充墙的抗震性能试验与有限元分析

震害显示填充墙的破坏不仅会造成严重的经济损失,还会影响建筑的使用功能,阻碍震后的救援工作,因此,增强填充墙的抗震性能对提升建筑结构整体的抗震韧性有重要意义。提出了一种分缝耗能的低损伤砌体填充墙,通过在墙内合理设置竖缝和连接件,来减轻墙体在地震作用下的损伤;开展了足尺分缝耗能填充墙的低周往复加载试验,对其损伤演化机理和滞回特性进行了研究;并建立了分缝耗能填充墙的精细有限元模型,对其滞回性能进行模拟。研究结果表明:该文提出的分缝耗能砌体填充墙有效可行,相比于普通砌体填充墙,变形能力提升了约1.6倍,在相同位移下的损伤程度明显减轻,层间位移角1/200时,分缝耗能填充墙仍处于轻微损伤状态,层间位移角达到1/100时,分缝耗能填充墙处于中等损伤状态。