隔震换能减震控制系统实用设计方法研究

从能量的角度研究对隔震换能控制系统对建筑结构的减震控制作用,它既能通过转换地震能量来减轻结构的振动,又可以利用转换来的能量作进一步的振动控制.通过研究换能装置的控制力与隔震层刚度比的关系,提出了换能装置控制力的建议公式,并研究了不同换能装置与隔震层设计组合对换能效率和控制效果的影响,给出了隔震换能系统的设计流程,可使隔震换能系统换能效率达到70％左右,振动控制效果达到65％以上.     

隔震换能结构体系的能量分析

将换能器安装在隔震结构的隔震层处,由结构和换能装置构成隔震换能结构体系,它既可以将地震输入给结构的部分能量转换成液压能,实现地震能量的转换,又能减小隔震层的水平位移,降低对隔震层的技术要求,降低造价。本文详细研究地震输给隔震换能结构体系的能量在体系各部分的分配,并与普通隔震结构对比,从能量的角度揭示隔震换能体系的换能控制原理。     

组合基础隔震结构双向地震反应分析

本文采用双向耦合恢复力模型模拟组合隔震系统中隔震支座的双向耦合效应,对组合基础隔震结构进行了单向和双向地震反应对比分析,分析表明在水平双向地震作用下结构各层的加速度反应较小,隔震层的层间位移较大,而上部结构的层间位移较小,并且在水平双向地震作用下,支座的最大位移明显大于单向地震作用时支座的最大位移,因而应考虑水平双向地震作用对组合基础隔震结构地震反应和隔震支座性能的影响。     

电气设备抗震性能对变电站系统功能的影响分析

变电站是由一系列电气设备组成的复杂系统。目前,各类减、隔震装置可以显著提升电气设备的抗震性能,然而,单体设备抗震性能的提升对系统抗震性能的影响难以量化。在前期研究的基础上,通过参数分析确定了决定变电站抗震性能的关键设备,进一步量化了提升这些设备抗震能力对变电站系统抗震性能的影响程度,研究结果表明：不同类型电气设备对系统功能的影响模式不同且与系统功能需求相关;从系统功能的角度,隔离开关、电流互感器和断路器是变电站的薄弱环节,变压器的影响不大;采用减、隔震技术提高变电站的抗震能力应重点关注关键设备。     

高烈度区村镇带限位装置的滑移隔震系统的参数敏感性分析

以总输入能量、综合耗能比和隔震层最大位移为响应指标,以能量法为基础,采用正交试验的方法,计算并分析了村镇建筑在地震作用下的响应指标对系统参数的敏感性,探讨了系统参数对响应指标的影响趋势。研究表明:系统参数对总输入能量的影响与场地类别关系不大,但对综合耗能比和隔震层最大位移的影响与场地类别关系较大,Ⅳ类场地条件下的综合耗能比和隔震层最大位移要远远大于其在Ⅱ类和Ⅲ类场地条件下的值,最后,对村镇带限位装置的滑移隔震系统的系统参数给出了建议的取值。     

LRB基础隔震结构在极罕遇地震作用下的抗震性能研究

以典型的四层、六层和八层LRB(铅芯橡胶隔震支座)基础隔震结构为研究对象,通过大量的弹塑性时程分析,对极罕遇地震作用下的地震响应特点进行了分析;采用参数化方法,研究了隔震系统的力学性能参数和上部结构屈服强度比的变化对LRB基础隔震结构抗震性能的影响。结果表明:在极罕遇地震作用下,LRB基础隔震结构上部结构首层的层间位移角和延性系数明显增大;延长LRB隔震系统的隔震周期或选择最优的特征屈服强度比,均可显著降低上部结构的塑性变形程度,但LRB屈服位移的变化对隔震结构的响应几乎无影响;LRB隔震系统参数确定后,隔震结构上部结构的损伤状态主要与上部结构力学性能参数中的屈服强度比相关,增大上部结构的屈服强度比,可以显著降低上部结构的层间位移角和延性系数,但是隔震支座的平均最大剪应变会增大,可以选用橡胶剪切模量大或者直径大、第二形状系数小的LRB隔震支座。     

超大型混凝土冷却塔基础隔震与层间隔震性能对比研究

为研究隔震技术对超大型冷却塔抗震性能的影响,以某混凝土冷却塔为研究对象,利用SAP2000分别建立基础隔震与层间隔震的冷却塔有限元模型,开展了结构动力特性分析和非线性时程分析,与非隔震冷却塔相比,对比分析了基础隔震与层间隔震的隔震效果。研究结果表明：基础隔震技术与层间隔震技术均能有效地延长冷却塔结构的自振周期,降低结构地震反应,第一阶自振周期延长至近3倍,整体平动模态提前至前两阶,扭转模态提前至第三阶。对比基底剪力,基础隔震的减震性能略优于层间隔震;对比相对位移,喉部以上,基础隔震与层间隔震的冷却塔减震效果基本相同,喉部以下,层间隔震的减震效果优于基础隔震;对比加速度放大系数,塔筒各位置处基础隔震的减震效果均优于层间隔震,支柱位置处,与非隔震冷却塔相比,基础隔震的加速度略有放大。研究结果可为冷却塔的减隔震分析提供参考。     

摩擦板与弹簧协同隔震的性能研究

从理论上分析了干摩擦板-复位弹簧隔震系统的隔震性能,根据拉格朗日方程推导了结构无隔震系统、地下室顶板与基础顶面分别设置隔震系统地震动力反应分析计算公式。分析与计算结果表明:结构设置减震系统后楼层位移、层间位移、速度及加速度明显减小。在基础顶面设置隔震系统比地下室顶板设置隔震系统具有较好的隔震效果。     

铅芯橡胶支座隔震钢框架结构体系振动台模型试验研究

设计并完成了铅芯橡胶支座隔震钢框架结构体系的振动台模型试验,研究刚性地基上隔震结构体系的动力特性和隔震效果,为进一步开展考虑土-结构相互作用的隔震结构体系振动台模型试验提供数据对比。试验结果表明:刚性地基上隔震结构体系具有良好的隔震性能,隔震效果显著,输入地震动的频谱特性和加速度峰值对隔震结构的隔震效率影响较大。     

基础隔震结构健康监测系统的设计与实现(Ⅰ):系统设计

在医院、教学楼等建筑中广泛采用隔震技术,能降低地震对上部结构的破坏作用。虽然隔震技术经过几十年的发展已趋于成熟,但环境及其他荷载对隔震结构性能的影响规律、结构设计的合理性以及震后结构状态评估等问题,仍需建立隔震结构健康监测系统对施工、运营期的结构响应进行监测,并对其进行评估与验证。首先,针对基础隔震结构的特点,研究了基础隔震结构的主要监测内容;在此基础上提出基础隔震结构健康监测系统的总体设计要求及原则,根据不同监测对象(整体与局部监测量)给出基础隔震结构传感器布置原则和数据采集系统软硬件设计原则,提出基础隔震结构设计验证与安全评定方法;最后给出基础隔震结构健康监测值得进一步研究的问题。     

SCIENCE CHINA Earth Sciences SUBJECT INDEX TO VOLUME 57(2014)

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Distribution of throughfall and stemflow in multi‐strata agroforestry,perennial monoculture,fallow and primary forest in central Amazonia,Brazil

The partitioning of rain water into throughfall, stemflow and interception loss when passing through plant canopies depends on properties of the respective plant species, such as leaf area and branch angles. In heterogeneous vegetation, such as tropical forest or polycultural systems, the presence of different plant species may consequently result in a mosaic of situations with respect to quantity and quality of water inputs into the soil. As these processes influence not only the water availability for the plants, but also water infiltration and nutrient leaching, the understanding of plant effects on the repartitioning of rain water may help in the optimization of land use systems and management practices. We measured throughfall and stemflow in a perennial polyculture (multi‐strata agroforestry), monocultures of peach palm (Bactris gasipaes) for fruit and for palmito, a monoculture of cupuaçu (Theobroma grandiflorum), spontaneous fallow and primary forest during one year in central Amazonia, Brazil. The effect on rain water partitioning was measured separately for four useful tree species in the polyculture and for two tree species in the primary forest. Throughfall at two stem distances, and stemflow, differed significantly between tree species, resulting in pronounced spatial patterns of water input into the soil in the polyculture system. For two tree species, peach palm for fruit (Bactris gasipaes) and Brazil nut trees (Bertholletia excelsa), the water input into the soil near the stem was significantly higher than the open‐area rainfall. This could lead to increased nutrient leaching when fertilizer is applied close to the stem of these trees. In the primary forest, such spatial patterns could also be detected, with significantly higher water input near a palm (Oenocarpus bacaba) than near a dicotyledonous tree species (Eschweilera sp.). Interception losses were 6·4% in the polyculture, 13·9 and 12·3% in the peach palm monocultures for fruit and for palmito, respectively, 0·5% in the cupuaçu monoculture and 3·1% in the fallow. With more than 20% of the open‐area rainfall, the highest stemflow contributions to the water input into the soil were measured in the palm monocultures and in the fallow. Copyright © 1999 John Wiley & Sons, Ltd.     

A Monte Carlo study of rainfall forecasting with a stochastic model

A procedure for short-term rainfall forecasting in real-time is developed and a study of the role of sampling on forecast ability is conducted. Ground level rainfall fields are forecasted using a stochastic space-time rainfall model in state-space form. Updating of the rainfall field in real-time is accomplished using a distributed parameter Kalman filter to optimally combine measurement information and forecast model estimates. The influence of sampling density on forecast accuracy is evaluated using a series of a simulated rainfall events generated with the same stochastic rainfall model. Sampling was conducted at five different network spatial densities. The results quantify the influence of sampling network density on real-time rainfall field forecasting. Statistical analyses of the rainfall field residuals illustrate improvement in one hour lead time forecasts at higher measurement densities.     

Anthropogenic Eutrophication and Red Tide Outbreak in Lacustrine Systems of the Kashmir Himalaya

Red tide, a recurrent phenomenon has become conspicuous in several Kashmir lake ecosystems since 1991. The responsible organism (Euglena pedunculata), a rare flagellate rediscovered in the Kashmir Himalaya (Khan 1993) caused first and unprecedented red tide outbreak, constituting a maximum of 96% of resident numerical phytoplankton density in Dal Lake. At present, conflicting hypotheses exist on the generation of causal assemblage(s) imparting redness to waters: Jeeji Bai (1991) linked its origin to acid precipitation – a fallout of burning oil‐fields during the Gulf War – whilst Khan (1993) holds local factor(s) responsible. Field/experimental studies support the latter contention that the influx of untreated sewage, in unison with warm temperatures, high levels of PhAR, iron and interruption to hydrological flow‐pattern together with absence/or reduction in grazing activity created conducive environmental milieu for red tide outbreak. Dal Lake “red tide” drifted the bloom‐inoculum to other waters, including Lake Wular, where additional ecological niches were carved out, threatening the aesthetic value and biological diversity of Kashmir lakes. Ecological monitoring indicates frequent seasonal red tide occurrence in Dal Lake (including summer‐autumn event of 1998) which testifies its unabated eutrophication status. Further studies are needed on ecological adaptability and biogeographic distribution of this rare and unique red tide‐causing flagellate.