共查询到20条相似文献，搜索用时 875 毫秒
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《地震工程与工程振动》2017,(1)
本文运用SAP2000对一10层钢筋混凝土框架结构在双向地震作用和单向地震下,考虑土-结构相互作用并计入重力二阶效应影响和不考虑二阶效应、采用刚性地基假定的情况分别进行动力时程分析,对比研究该结构抗震性能的变化规律。然后针对竖向地震作用展开进一步研究,探讨地震波的竖向和水平PGA比值对结构地震响应的影响规律。研究表明:(1)近场双向地震作用下,采用刚性地基假定,分析得到的结构地震响应比考虑土-结构相互作用时小,偏于不安全。(2)近场双向地震作用下地基-基础-RC框架结构的地震响应比单向地震作用时大,且随着场地土变软,不利影响增大,表明竖向地震作用不容忽视。(3)近场地震中,考虑土-结构相互作用的情况下,结构抗震性能在地震竖向和水平PGA比值为0.6左右时所受影响最小,比值为0.7左右时所受影响最大。 相似文献
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地震区城镇建筑框架结构概念设计 总被引：1，自引：0，他引：1
自从唐山大地震以来，我国地震专家及其科技人员通过长期分析研究地震所造成的危害，对地震的经验不断总结，对地震的破坏规律有了更深刻的认识，提出了“概念设计”的设计理念，要使结构具有良好的抗震性能和足够的抗震能力，“概念设计”比“结构设计”更为重要。主要通过对钢筋混凝土框架结构震害的统计分析，阐述了抗震“概念设讣”的有关问题。通过建筑场地选择、地基基础的设计、结构体系及结构构件的抗震设计等方面的分析，明确了“概念设计”的原则和要求，特别是针对工程实际中的钢筋混凝土结构的延性设计问题，总结了延性设计的要点及其实现方法，从而消除了建筑中的薄弱环节，提高了房屋结构的整体抗震性能。 相似文献
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汶川地震反应谱特征周期统计分析 总被引：1，自引：0，他引：1
反应谱特征周期反映了地震动频谱特性,也是抗震设计中重要的特征参数.为了研究汶川特大地震反应谱特征周期的特性,本文以汶川地震中173个有详细地勘场地上的强震动记录为基础,统计分析了不同场地类别和断层距的反应谱特征周期,并与我国现行抗震设计规范中特征周期的规定值进行比较.本文研究结果显示随着场地变软,特征周期平均值有增大趋势;与汶川特大地震中反应谱特征周期的统计结果相比,我国抗震设计规范规定的远场反应谱特征周期值偏小. 相似文献
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整理并分析汉中地区的地震背景、地震动参数和地质灾害,调查区域内地震动参数有差异的9类样本行政镇的931栋典型农村房屋,研究典型农村房屋的结构类型、抗震概念设计和建造场地等因素对房屋抗震性能的影响。结果表明:汉中地区地质构造复杂,深大断裂发育,94.7%的区域为灾害易发区,存在4个地震烈度异常区;农村既有房屋结构类型有土木结构、砖木结构、砖混结构和框架结构,其中砖木结构和砖混结构是主要的抗震结构类型,框架结构是新型抗震结构类型;区域内农村房屋的建造场地条件危险性大并且抗震概念设计不足,房屋震害严重,村民的工程地质和地震地质等相关知识匮乏。该研究可为村镇房屋的防震减灾工作提供参考。 相似文献
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从欧洲抗震设计规范的一般规定浅谈结构抗震概念设计的重要性 总被引：1，自引：0，他引：1
由于地震的作用以及在这种作用下的结构与构件的受力状况的复杂性和不确定性,结构抗震设计的计算假定与实际情况存在各种差异,甚至有时还根本无法计算.因此在这种情况下,为确保抗震结构性能,就不得不依赖结构抗震的概念设计.结构抗震概念设计是指工程师们根据结构地震破坏的形态和长期积累的实际工程经验等总结形成的符合工程师专业知识的基... 相似文献
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以抗震设防7度区的某高层钢框架结构建筑为研究对象,研究基于隔震就位连接技术的高层钢框架结构建筑抗震技术。对研究对象采用抗震就位连接技术,通过在隔震层中设置弹性滑板支座、厚层橡胶隔震支座化黏滞阻尼器等隔震装置提升研究对象自振周期,降低其上部结构受地震作用的影响程度,增强抗震性能。对研究对象进行模态分析与时程分析,结果显示,所研究隔震技术在显著提升研究对象自振周期,使其摆脱场地特征周期的同时,也能够延缓扭转振型的形成,显著降低地震作用对研究对象上部结构的影响,说明所研究技术的运用具有较好的抗震效果。 相似文献
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特征周期是抗震设计反应谱的重要参数,开展特高压电气设备抗震设计反应谱特征周期的研究,具有重要的理论意义和工程应用价值。对美国、日本等世界范围内的1448 条Ⅲ类场地水平向强震记录进行了统计分析,结果表明震级、震中距对特征周期有较大影响;强震记录特征周期的80%分位数结果约为0.9s。对全国近年来已通过评审的312 个Ⅲ类场地的地震安全性评价结果进行了统计分析,70%分位数的特征周期为0.9s。结合相关规范的对比分析,建议特高压电气设备抗震设计反应谱的特征周期取0.9s,可有效保证特高压电气设备的地震安全。 相似文献
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特高压电气设备抗震设计反应谱特征周期取值研究 总被引：2，自引：1，他引：1
特征周期是抗震设计反应谱的重要参数,开展特高压电气设备抗震设计反应谱特征周期的研究,具有重要的理论意义和工程应用价值。对美国、日本等世界范围内的1448条Ⅲ类场地水平向强震记录进行了统计分析,结果表明震级、震中距对特征周期有较大影响;强震记录特征周期的80%分位数结果约为0.9s。对全国近年来已通过评审的312个Ⅲ类场地的地震安全性评价结果进行了统计分析,70%分位数的特征周期为0.9s。结合相关规范的对比分析,建议特高压电气设备抗震设计反应谱的特征周期取0.9s,可有效保证特高压电气设备的地震安全。 相似文献
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Seismic demand estimation for a structure is a critical issue for seismic performance assessment so that the potential damage can be estimated realistically. Many researchers proposed simplified methods to estimate the demand of a structure under strong ground motions. However, most of them did not consider degradation and collapse potential of the structures. Even some of theme considered the degradation effect, stiffness and strength degradation effects were considered separately without collapse potential caused by dynamic instability. In this study, collapse potential of SDOF systems caused by dynamic instability with stiffness and strength degradation has been investigated. Nonlinear time history analyses were performed, using an energy-based, strength and stiffness degraded hysteretic model that considers the collapse potential, with 160 earthquake acceleration time histories. An equation was proposed for the estimation of collapse period of SDOF systems as a function of certain strength reduction factor, ductility level and post-capping stiffness ratio. Finally, effects of parameters of the considered hysteretic model and local site conditions on the collapse period were investigated. 相似文献
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V. T. Buchwald 《地球物理与天体物理流体动力学》2013,107(1):359-367
AbstractA simple first order perturbation procedure is used to obtain an equation for divergent planetary waves when the period is much greater than the pendulum day. For unbounded regions the equation is the s2me as one derived by Longuet-Higgins (1965), but in bounded basins it is different. As an example, the eigen frequencies of a rectangular basin are calculated for a number of values of the parameters.The energy density of planetary waves is also considered with results which correct those of Buchwald (1972) in the case of bounded basins. 相似文献
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Haruka Tsunetaka 《地球表面变化过程与地形》2021,46(14):2984-2998
The intensity of rainfall events with potential to cause landslides has varying temporal characteristics. In this study, the time at which the 72-h accumulated rainfall reached its maximum was used to standardize the period of rainfall measurement. The proposed standardization of the rainfall period was used in conjunction with the return level of rainfall intensity, obtained from intensity–duration–frequency curves, to investigate rainfall intensity anomalies associated with 10 hazardous rainfall events that triggered numerous landslides at the regional scale in Japan. These landslides included shallow landslides in volcanic and non-volcanic areas, as well as deep-seated landslides. The rainfall events that triggered the shallow landslides were divided into two types: downpours that repeatedly reached close to the 100-year return level within approximately 3–4 h, and accumulated rainfall that reached close to 200–400 mm over longer time intervals but within 72 h. Lithological differences seemed unrelated to the differences between the two types of shallow-landslide-triggering rainfall; however, precipitation >1000 mm was necessary to trigger deep-seated landslides. Although the characteristics of the hyetographs differed markedly among the landslide-triggering rainfall events, all the landslides could have been triggered when the mean rainfall intensity reached the 100-year rainfall level during the standardized period. Thus, the landslide trigger can be evaluated indirectly based on the increase in the return level of the mean rainfall intensity, which could provide a means for estimating the time of landslide occurrence. 相似文献
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场地周期作为场地固有特性是评价场地条件的重要参数。本文在详细阐述场地周期基本概念的基础上将其区分为场地卓越周期和场地基本周期,并详细分析总结了这两种周期的不同确定方法。场地卓越周期是地震波在场地中传播幅值被明显放大频带对应的周期,主要是是利用地脉动或强震动记录通过频谱分析得出的,给出的是场地周期的范围,有时根据频谱曲线会无法识别场地卓越周期。场地基本周期是将场地假定为覆盖在均匀、各向同性线弹性基岩半空间上的水平成层均匀、各项同性的线弹性土层场地,无阻尼的情况下第一振型对应的周期。通过场地的物理参数(剪切波速或剪切模量,土层厚度和质量密度等)计算得出,计算方法包括解析法、数值法和简化法,实际应用中经常采用的方法是简化法。一般地,两种方法的确定结果不尽相同,在场地不太厚,场地土不太软的情况下,二者的确定结果相近。 相似文献
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Mr. Markus Bath 《Pure and Applied Geophysics》1948,12(3-4):121-126
Summary The microseisms recorded at Uppsala have been studied for the time 1907–1947 with regard to long period variations. There
is clear evidence of an 11 year variation and slight indications of a 28 month variation. The 11 year variation is from 1923
negatively correlated to the sunspot frequency and is explained by corresponding meridional displacements of the dominant
cyclonic tracks.
Zusammenfassung Die in Uppsala registrierte Bodenunruhe ist für die Zeit 1907–1947 betreffs langperiodischen Schwankungen untersucht worden. Eine 11-j?hrige Variation wird festgestellt und es gibt weiter Anzeichnungen einer Variation von 28 Monaten. Die 11-j?hrige Variation ist seit 1923 zur Sonnenflecken-frequenz negativ korreliert und ist durch entsprechende meridionale Verschiebungen der am meisten betretenen Zyklonenbahnen, erkl?rt.
Riassunto L'agitazione microsismica registrata a Uppsala nel quarantennio 1907–1947 venne esaminata in vista di determinare le oscillazioni di lungo periodo. Si è accertata una oscillazione undecennale, trovandosi altresi indizi per una oscillazione di 28 mesi. Dal 1923 l'oscillazione undecennale manifesta una correlazione negativa con la frequenza delle macchie solari e viene spiegata con i corrispondenti spostamenti meridionali delle rotte cicloniche dominanti.相似文献
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黄敏 《地震地磁观测与研究》2008,29(2):70-74
回顾了“RSFS”反馈式短周期地震计前期研究和设计,通过分析电子反馈网络存在的问题,提出了新的解决方案。新方案采用深度阻尼反馈环电路,减少需要精确选配的阻容元件,具有精简装配调试工序和节约工时的优点;新方案对地震计机械部分参数精度一致性要求降低,提高了部件互换性。新方案对地震计的动态范围、幅频特性在整个观测频带内保持平直,参数一致性带来益处,并可以降低地震计的制作成本。 相似文献
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在灾后救援中,交通系统既是救援物资运输的通道,也是抢救和安置受伤群众的重要保证。然而破坏性地震后,交通系统的破坏以及急增的运输量给伤亡人员的转移和救援物资的运送都带来了极大的困难。因此,在灾后第一时间给出最优路径的建议,帮助救援队快速高效的进行灾后的救援工作,有重要的意义。考虑震后条件及应急需求,对已有的最短路径,最大容量路径进行改进。利用Dijkstra算法和深度优先算法,考虑路段的通行能力、抢修效率和应急期限,给出了以最大运输量为目标的最优路径的评价方法,为震后应急决策提供技术支持。 相似文献
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J. T. Shiau 《Stochastic Environmental Research and Risk Assessment (SERRA)》2003,17(1-2):42-57
Extreme hydrological events are inevitable and stochastic in nature. Characterized by multiple properties, the multivariate
distribution is a better approach to represent this complex phenomenon than the univariate frequency analysis. However, it
requires considerably more data and more sophisticated mathematical analysis. Therefore, a bivariate distribution is the most
common method for modeling these extreme events. The return periods for a bivariate distribution can be defined using either
separate single random variables or two joint random variables. In the latter case, the return periods can be defined using
one random variable equaling or exceeding a certain magnitude and/or another random variable equaling or exceeding another
magnitude or the conditional return periods of one random variable given another random variable equaling or exceeding a certain
magnitude. In this study, the bivariate extreme value distribution with the Gumbel marginal distributions is used to model
extreme flood events characterized by flood volume and flood peak. The proposed methodology is applied to the recorded daily
streamflow from Ichu of the Pachang River located in Southern Taiwan. The results show a good agreement between the theoretical
models and observed flood data.
The author wishes to thank the two anonymous reviewers for their constructive comments that improving the quality of this
work. 相似文献