Response of seismically isolated buildings considering poundings

Numerical simulations and parametric studies have been used to investigate the influence of potential poundings of seismically isolated buildings with adjacent structures on the effectiveness of seismic isolation. Poundings are assumed to occur at the isolation level between the seismically isolated building and the surrounding moat wall. After assessing some common force‐based impact models, a variation of the linear viscoelastic impact model is proposed to avoid tensile impact forces during detachment, while enabling the consideration of permanent plastic deformations at the vicinity of the impact. A large number of numerical simulations of seismically isolated buildings with different characteristics have been conducted under six earthquake excitations in order to investigate the influence of various design parameters and conditions on the peak floor accelerations and interstorey deflections during poundings. The numerical simulations demonstrate that poundings may substantially increase floor accelerations, especially t the base floor where impacts occur. Higher modes of vibration are excided during poundings, increasing the interstorey deflections, instead of retaining an almost rigid‐body motion of the superstructure, which is aimed with seismic isolation. Impact stiffness seems to affect significantly the acceleration response at the isolation level, while the displacement response is more insensitive to the variation of the impact stiffness. Finally, the results indicate that providing excessive flexibility at the isolation system to minimize the floor accelerations may lead to a building vulnerable to poundings, if the available seismic gap is limited. Copyright © 2007 John Wiley & Sons, Ltd.     

Green schools in Taiwan – Effects on student sustainability consciousness

In recent decades, the Taiwanese government has worked actively to implement the concept of a sustainable Taiwan. As an important step in their strategy, the Ministry of Education has decided to promote the Green School Partnership Project in Taiwan (GPPT). However, academic research and critical reflection on the effects of this environmental and sustainability education initiative are lacking. Therefore, this study focuses on filling this gap by means of a nationwide generalizable effect study. The sampling allowed comparisons between the sixth, ninth, and twelfth grades in GPPT and non-GPPT schools and considered the geographic location (north, center, and south of Taiwan) as well as socio-economic area of the schools. A total of 1741 students participated, answering a questionnaire that focused on student sustainability consciousness (SC) and its components (i.e., knowingness, attitudes, and behaviors in relation to sustainability). Data were analyzed through structural equation modeling. Our findings make an important empirical contribution, indicating that GPPT schools and non-GPPT schools have a similar effect on the SC of students, i.e. schools engaged in the GPPT do not enhance student SC. In addition, the gender gap regarding SC increased consistently with each increasing grade level, yielding higher mean values for the girls than for the boys. Furthermore, an adolescent dip occurred in the student SC, especially with regard to student sustainability behavior. Given these findings, implications for developing GPPT are discussed; this research could provide valuable information about the educational transformation process to enhance environmental and sustainability behavior among students in Taiwan.     

贵州省近40年耕地功能转型评价及演变差异分析

梳理1978年之后贵州省农业政策及农业农户概况,构建耕地功能评价指标体系,并运用熵权法计算指标权重与其功能值,对耕地多功能进行分类和评价,对比全省及各个州市耕地在不同社会经济条件下所承载的功能,分析差异及原因,研究表明:（1）贵州省耕地功能呈下降趋势,功能转型从2006年前后开始,各州市存在一定差异,经济发展较快的地区在2004年前后已提前转型,经济发展较慢的地区在2012年前后转型;（2）耕地功能存在空间分布差异,主要与地区耕地压力和经济发达程度组合状况有关,低耕低压力高GDP（如遵义、六盘水）耕地功能值最高,高耕低压力高GDP（如贵阳市）则次之,高压力低GDP（如安顺等地区）再次之,低压力低GDP（如黔南等地）最低;（3）耕地数量减少,耕地化学品负荷加剧,建议注重耕地生态保护,减少以过度化学品的投入换取粮食产出等不合理做法;从当地实际出发选择适合的农业发展方式,协调粮经作物、种养业发展的关系,推动农业结构优化升级。      

中国旅游经济平衡区域经济差距效果评价

为了全面、客观地评价旅游经济在中国区域经济差距中的作用效果,通过集对分析与旅游经济平衡指数对2001-2011年中国旅游经济平衡区域经济差距的效果进行了评价,结果显示:1)集对分析和旅游经济平衡指数是分别从地区人均旅游收入和地区总规模的不同角度分析旅游经济平衡区域经济差距效果的方法;2)从人均旅游收入的角度分析,2001-2011年中国旅游经济对区域经济差距平衡发挥了积极作用,但从各省旅游总收入及其比重角度分析,其作用是负面的;3)社会经济重大事件会对旅游经济平衡区域经济差距的效果产生影响;4)我国四大区域之间旅游经济平衡区域经济差距效果存在显著差异。     

Study of Seismic Clusters at Bahía de Banderas Region,Mexico

The coast in the state of Jalisco and south of Nayarit is located within a region of high seismic potential, increasing population, and tourism development. This motivated Civil Defense authorities of Jalisco and the Universidad de Guadalajara to launch in the year 2000 the assessment of the seismic risk of the region. This work focuses in the seismicity study of the area of Bahía de Banderas and northern coast of Jalisco, which is actually a seismic gap. We perform an analysis of available seismograms to characterize active crustal structures, their relationship to surface morphology, and possible extent of these structures into the bay shallow parts. The data consist of waveforms recorded during 2003 when the seismograph network spanned the region. Our method is based on the identification of seismic clusters or families using cross-correlation of waveforms, earthquake relocation and modeling of fault planes. From an initial data set of 404 located earthquakes, 96 earthquakes with M_L < 3.6 are related to 17 potentially active continental structures. We present fault plane model for 11 structures. A subgroup of 7 structures is aligned parallel to the Middle America Trench, as a possible consequence of oblique subduction. The foci of the earthquakes were grouped into clusters corresponding to fault dimensions of hundred of meters, may be considered as asperities or barriers in tectonic structures with lengths between 10 and 30 km. These structures could generate shallow earthquakes with magnitudes between 5.0 and 6.0 and represent an additional seismic threat to the region.     

孤立波与带窄缝双箱相互作用模拟研究

针对孤立波与带窄缝双箱的作用问题,应用时域高阶边界元方法建立了二维数值水槽。其中,自由水面满足完全非线性运动学和动力学边界条件,对瞬时自由表面流体质点采用混合欧拉-拉格朗日法追踪,采用四阶龙格库塔法对下一时刻的自由水面的速度势和波面升高进行更新。采用加速度势法求解物体湿表面的瞬时波浪力。采用推板方法生成孤立波。通过模拟孤立波在直墙上的爬高以及施加在直墙上的波浪力,并与已发表的实验和数值结果对比,验证本数值模型的准确性。通过数值模拟计算研究了窄缝宽度、方箱尺寸对波浪在箱体迎浪侧爬高,窄缝内波面升高,箱体背浪侧透射波高及箱体受波浪荷载的影响。同时研究了有一定时间间隔的双孤立波与带窄缝双箱系统作用问题。     

滇西施甸地区晚泛非运动的地层学和岩石学响应

保山地块的寒武系露头少,研究范围有限。长期以来,地学界对寒武系与奥陶系之间的接触关系存在较大争议,有人认为是整合接触,有人认为是假整合接触,囿于过去的工作精度,目前尚无定论。近年来,在保山施甸地区开展1∶5万区调工作时发现,区内普遍缺失早奥陶世沉积,仅在施甸半坡一带有中奥陶统,在大寨一带,中上奥陶统蒲缥组直接平行不整合在上寒武统保山组之上,结合晚寒武世—早奥陶世业已存在的岩浆活动,认为这是晚泛非运动的远程响应。     

不同脉冲电流冲击下多级石墨间隙匹配特性研究

针对石墨间隙不同间距的配合使用问题,根据其工作原理并结合汤逊气体放电理论,采用1.2/50 μs开路电压波和8/20μs短路电流波对不同级数的石墨间隙进行试验,结果表明:电压保护水平随着间隙距离的增加而增加,当间隙距离超过2 mm时,电压保护水平远大于IEC规定的2.5 kV.石墨间隙的残压、通流和动作响应时间都随着石...     

祁连山地震带西段2019年以来小震空区现象分析

2019年10月1日以来,祁连山地震带西段出现MS≥3.0地震平静现象,截至2020年5月27日,平静时长已达176天,但该地区外围地震相对活跃.分析认为,在祁连山地震带西段形成MS≥3.0地震空区,其长轴为510 km,方位角为90°,短轴为410 km,围空地震12个,最大方位角不超过120°,空区内部与外围形成围...     

地震动态空区法预报中强震的进一步讨论

将动态空区预报地震的方法同静态空区法作了详细的比较分析．发现用动态空区法所确定的震中位置的精度比静态空区法高，而且，在估计发震时间和震级方面也比静态空区法有很大的改善．