Wavelet‐based non‐stationary response analysis of a friction base‐isolated structure     

Biswajit Basu  Vinay K. Gupta 《地震工程与结构动力学》2000,29(11):1659-1676

A wavelet‐based stochastic formulation has been presented in this paper for the seismic analysis of a base‐isolated structural system which is modelled as a two‐degree‐of‐freedom (2‐DOF) system. The ground motion has been modelled as a non‐stationary process (both in amplitude and frequency) by using modified Littlewood–Paley basis wavelets. The proposed formulation is based on replacing the non‐linear system by an equivalent linear system with time‐dependent damping properties. The expressions of the instantaneous damping and the power spectral density function (PSDF) of the superstructure response have been obtained in terms of the functionals of input wavelet coefficients. The proposed formulation has been validated by simulating a ground motion process. The effect of the frequency non‐stationarity on the non‐linear response has also been studied in detail, and it has been clearly shown how ignoring the frequency non‐stationarity in the ground motion leads to inaccurate non‐linear response calculations. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

A guide for mineral exploration through the regolith in the Yilgarn Craton,Western Australia     

R. R. Anand  C. R. M. Butt 《Australian Journal of Earth Sciences》2013,60(8):1015-1114

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Dynamics of elastic–plastic shear frames with secondary structures: shake table and numerical studies     

Christoph Adam 《地震工程与结构动力学》2001,30(2):257-277

Results from experimental and numerical studies of earthquake‐excited small‐scale primary–secondary structures are presented. The primary structure considered is a plane three‐storey shear frame with a fundamental frequency of 5.5 Hz. The columns of the first floor are built with soft aluminium and they are stressed beyond its linear range of behaviour. After each test the elastic–plastic columns are replaced by a new set of undeformed virgin aluminium bars. The elastic–plastic shear frame is tested with and without an attached secondary structure. The secondary structure is modelled as an elastic SDOF oscillator, and its natural frequency is tuned to the fundamental frequency of the shear frame. Alternatively, the oscillator is mounted on the horizontal beam of the second and third floor. The base excitation of the structural model is characterized by a broad band random process with constant spectral density in a frequency range between 3 and 30 Hz. In the numerical study, the digital recorded acceleration of the base excites the mechanical model of the investigated structures. Numerical outcomes assuming fictitious unlimited elastic material behaviour of the shear frame are set in contrast to results from experiments and computational simulations where the measured non‐linear force displacement relation of the elastic–plastic floor is approximated by a piecewise linear curve. The effect of elastic–plastic materials on the dynamic interaction between primary and secondary structure is shown and the difference to unlimited elastic material behaviour is worked out in detail. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

Aseismic roof isolation system: analytic and shake table studies     

Roberto Villaverde  Gilberto Mosqueda 《地震工程与结构动力学》1999,28(3):217-234

Presented are the features of a roof isolation system that is proposed as a device to reduce the seismic response of buildings. Presented also are the details of and results from analytical and experimental studies conducted with a small-scale laboratory model to assess the feasibility and effectiveness of such a device. The roof isolation system entails the insertion of flexible laminated rubber bearings between a building’s roof and the columns that support this roof, and the installation of viscous dampers that are connected to the roof and a structural element below the roof. It is based on the concept of a damped vibration absorber and on the idea of making the roof, rubber bearings, and viscous dampers respectively constitute the mass, spring, and dashpot of such an absorber. The model considered in the analytical and experimental studies is a 2·44-m high, five-storey, moment-resisting steel frame, with a fundamental natural frequency of 2·0 Hz. In the experimental study the frame is tested with and without the proposed roof isolation system on a pair of shaking tables under a truncated version of one of the accelerograms from the 1985 Mexico City earthquake. In the analytical study, the frame is also analysed with and without such a system and under the same ground motion except that the ground motion accelerations are properly magnified to study the effec tiveness of the roof isolation system when the frame is stressed beyond its linear range of behavior. It is found that the suggested device effectively reduces the seismic response of the frame, although the extent of this reduction depends on how large its non-linear deformations are. Based on these findings, it is concluded that the proposed roof isolation system has the potential to become a practical and effective way to reduce earthquake damage in low- and medium-rise buildings. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   

地质图数据库现状与地质制图发展趋势   总被引：1，自引：0，他引：1  

杨星辰  吴珍汉  张素梅  高曦  韩乐乐  丁伟翠  杨艳  张宇  叶梦旎  杨亚琦 《高校地质学报》2020,26(1):100-110

地质图是地质信息最重要的载体之一,凝聚了人们对地质理论的研究成果和对地质过程的理解。随着大数据时代的到来,地质制图的指导理论和方法手段发生了翻天覆地的变化,全球的科学家运用新方法新技术建立了OneGeology、OpenGeoscience、NGMDB、地质云等一系列地质图相关的优秀数据库,这些数据库的有效运行为全球的地质工作者提供了海量的地学数据和便捷的信息服务。此次研究重点调研了国内外已有的地质图相关数据库及运行情况,为Deep-Time Digital Earth(DDE)计划整合全球地质图相关数据库、建设相关数据平台提供经验和基础;同时,回顾了地质制图的发展历史,介绍了与地质制图相关的技术手段和常用软件;最后,为了满足大数据时代经济社会对地质图信息资料服务的需求,结合DDE相关任务,对深化国际合作编图、创新计算机智能地质制图及网络共享服务等核心技术提出了新的展望。  相似文献   

Dynamics of seismic impacts in base-isolated buildings     

Praveen K. Malhotra 《地震工程与结构动力学》1997,26(8):797-813

A systematic study is made of the effects of seismic impacts between the base of an isolated building and the surrounding retaining wall. The analysis is performed without using gap elements or assuming values of the coefficient of restitution and the duration of impact. The analysis captures the effects of wave travel along the height of the building and of the associated energy loss. It poses no numerical difficulties. Results show that for elastic systems the base shear generated by impacts can be higher than the weight of the building; base shear increases with increase in the stiffness of the retaining wall, stiffness of the building and the mass of the base mat. A significant fraction of the initial kinetic energy of the system is lost by impacts; energy loss increases with increase in the stiffness of the retaining wall, system damping and mass of the base mat. © 1997 John Wiley & Sons, Ltd.  相似文献   

钢柱脚混凝土承台锚固性能弹塑性有限元分析   总被引：1，自引：1，他引：0  

张晓新  曹万林 《世界地震工程》2005,21(4):95-100

在试验研究基础上,采用ANSYS有限元分析程序,对钢柱脚混凝土承台在单向加载下的性能作了弹塑性分析,研究了其在竖向抗拔荷载作用下的开裂、变形及破坏的全过程,并在此基础上,建立了简化的抗拔承载力计算的桁架模型,计算结果与试验结果符合较好。  相似文献   

基础隔震结构的耗能分析   总被引：5，自引：0，他引：5  

党育  杜永峰  李慧  韩建平 《世界地震工程》2005,21(3):100-104

采用Bouc-wen模型,利用状态空间迭代法,对基础隔震结构进行了多质点的弹塑性时程分析,并根据此结果,利用能量方程,求得隔震结构的各项能量,绘制了各能量项时程曲线。以一实际工程为例,求得隔震结构的各项耗能情况,说明了基础隔震结构以减少地震输入和隔震层滞回耗能来减小对上部结构的损坏。  相似文献   

地震下结构振动的最优控制算法模型比较与改进   总被引：8，自引：0，他引：8  

杜永峰  李慧 《世界地震工程》2005,21(3):57-63

模拟地震激励输入结构的过程,将控制目标函数化解到每个时间步长上。用激励所产生的脉冲响应重新构造控制目标函数,直接从泛函变分出发,推导出了一种改进的最优控制算法,并用状态转移的数值方法加以实现。从概念上讲,本算法是一种更为合理的结构最优控制算法。算例表明,在相同控制能量下,本算法能更有效地削减响应峰值,且稳定性良好。  相似文献   

鄂尔多斯盆地富县地区二叠系山西组高分辨率层序地层学研究   总被引：1，自引：1，他引：0  

叶茂林  傅强  李维锋 《上海国土资源》2005,(1):10-14

运用高分辨率层序地层学原理,详细分析了鄂尔多斯盆地富县地区二叠系山西组地层沉积的基准面旋回特征,共识别出了2个长期旋回、4个中期旋回和8～12个短期旋回,并得出了两类可容空间的短期旋回识别特征。对不同井基准面旋回联井分析得出,储集层段多发育于短期基准面上升半旋回的水下分流河道、河口坝和浊流沉积砂体中,且砂体与前三角洲泥呈指状交叉,形成岩性油气藏。建立的研究区高分辨率层序地层格架对进一步的油气勘探具有指导性的意义。  相似文献