云南漾濞6.4级地震建筑结构震害特征调查分析          下载免费PDF全文

郭丽娜      刘金龙  温卫平  杜轲  丁勇    林均歧  孙刚 《世界地震工程》2021,(4):064-72

本文整理了云南大理州"5.21"6.4级地震震害调研与科考过程的部分成果。穿斗木架构结构和框架结构是云南大理州在低矮建筑和多高层建筑中广泛应用的两种结构形式。该研究基于震害调查结果,描述了地震过程中穿斗木架构结构和框架结构破坏的宏观现象,总结了两种典型结构的破坏形式,对震害成因进行了探讨。在此次震害调查过程中,科考人员还通过智能手机对结构基频进行了快速评估。在震后,研究人员对智能手机智能测振应用软件进行了更新,结合应用需求加入了测振地点和路线的地图信息,为震害调查与记录提供了便利。基于漾濞县震害科考与调研结果,为云南省穿斗木架构建筑及框架建筑的抗震方法与策略提出了建议,为震后建筑结构快速评价提供了新手段。  相似文献   

Local site effects on a high-pier railway bridge under tridirectional spatial excitations: Nonstationary stochastic analysis     

《Soil Dynamics and Earthquake Engineering》2013

This paper presents a theoretical nonstationary stochastic analysis scheme using pseudo-excitation method (PEM) for seismic analysis of long-span structures under tridirectional spatially varying ground motions, based on which the local site effects on structural seismic response are studied for a high-pier railway bridge. An absolute-response-oriented scheme of PEM in nonstationary stochastic analysis of structure under tridirectional spatial seismic motions, in conjunction with the derived mathematical scheme in modeling tridirectional nonstationary spatially correlated ground motions, is proposed to resolve the drawbacks of conventional indirect approach. To apply the proposed theoretical approach readily in stochastic seismic analysis of complex and significant structures, this scheme is implemented and verified in a general finite element platform, and is then applied to a high-pier railway bridge under spatially varying ground motions considering the local site effect and the effect of ground motion nonstationarity. Conclusions are drawn and can be applied in the actual seismic design and analysis of high-pier railway bridges under tridirectional nonstationary multiple excitations.  相似文献   

The scattering of Rossby waves from finite abrupt topography     

G. W. Owen  A. J. Willmott  I. D. Abrahams  H. Mansley 《地球物理与天体物理流体动力学》2013,107(3):219-239

The scattering of first mode linear baroclinic Rossby waves by a top-hat ridge in a continuously stratified ocean, with Brunt-Väisälä frequency that decays exponentially with depth below a surface mixed layer, is the subject of this study. A numerical mode matching technique is used to calculate the transmission coefficients for the propagating modes over the ridge. It is found that the scattered field depends crucially upon the stratification. For example, when the majority of the density variation is confined to a thin thermocline, corresponding to a small e-folding scale, gamma ^?1, for the Brunt-Väisälä frequency, a large amount of the incident wave energy is reflected by a small amplitude ridge. Appreciable energy conversion between the propagating barotropic and baroclinic modes takes place in this case. An asymptotic analysis for a small amplitude ridge is presented that confirms these numerical results. In the limit gamma ^?1→ 0, it is demonstrated that the scattered field in the continuously stratified ocean model differs markedly from the two-layer solution. The latter does not exhibit appreciable reflection of the incident wave energy for a small amplitude ridge. In conclusion, the application of a two-layer ocean model to describe Rossby wave scattering by ridges in place of a continuously stratified model cannot be recommended.  相似文献   

去除交通环境振动观测记录中本底振动的自互功率谱法   总被引：1，自引：1，他引：0       下载免费PDF全文

郑鑫  陶夏新  王福彤  解恒燕 《地球物理学报》2013,56(1):348-353

去除环境振动观测记录中的本底振动是提高信噪比、揭示交通环境振动特征的一个重要环节.本文在分析现有从交通环境振动观测记录中去除本底振动方法不足的基础上,从考虑本底振动与观测振动互相关性出发,提出了采用自互功率谱法去除本底振动的新方法,推导了计算公式,并通过实际算例论证了方法的可靠性.分析结果表明,本文提出的自互功率谱法能够更有效地去除观测数据中的本底干扰,获得更贴近实际的交通环境振动的功率谱、时程、振动级以及加权振级.在本底振动占优势的低频段,本文提出的方法较现有方法计算精度有明显的提高.  相似文献   

检波器-大地耦合系统特性的振动力学解释、模态参数识别及其对地震资料的影响与消除   总被引：1，自引：0，他引：1  

魏继东 《地球物理学进展》2013,28(4)

检波器-大地耦合系统处于地震数据采集的最前端,是地震采集中的基本问题.“耦合是指两个系统之间的相互作用.检波器和大地的耦舍是影响能量转换的重要因素之一,取决于两者之间接触的牢固程度,以及检波器的重量和接触面积等;该耦合系统中存在着自然谐振并有滤波效应”(R.E.Sheriff).多年来,对耦舍响应的研究主要集中在理论研究以及检波器耦合效果对比两个方面,并以感性描述、现象罗列居多.笔者在研究过程中设计了检波器-大地耦舍响应的测定方法,并实际测量了检波器-大地耦合响应.结果表明,检波器-大地耦合响应可以用“单自由度有阻尼的自由振动系统”来描述,涉及到“固有频率”以及“阻尼比”两个参数,并可用参数扫描法对其振动模态进行参数识别.当检波器埋置效果差时,耦合响应使得地震子波相位增加,分辨率降低;高频成分增加,信噪比降低(主要在高频端).根据测得的耦合响应对检波器接收到的数据进行“耦合反褶积”,将地震数据“还原为”地表下数十厘米处的介质振动,从而消除耦合响应,可以增强地震信号的“保真度”,提高信噪比与分辨率.由于地表介质的多变性,每一个检波器对应的耦合响应均不同,同一检波器组合中多个检波器的耦合响应存在一定差异;其中只要有一个检波器埋置差,其整体的耦合效果就会显著变差;因为耦合响应对地震数据的影响非常深刻并难以忽略,所以合成地震记录时也应该考虑耦合响应的影响.  相似文献   

Vibration analysis of steel structures including the effect of panel zone flexibility based on the energy method     

Hasan Ghasemzadeh  Hamid Rahmani Samani  Masoud Mirtaheri 《地震工程与工程振动(英文版)》2013,12(4):587-598

New approximate formulas are proposed to determine the natural frequencies of structures considering the effects of panel zone flexibility and soil-structure interaction. Several structures with various earthquake resisting systems are idealized as prismatic cantilever flexural-shear beams. Floor masses are considered as lumped masses at each story level and masses of columns are evenly distributed along the cantilever beam. Soil-structure interaction is considered as axial and rotational springs, whose potential energy are formulated and incorporated into overall potential energy of the structure. Subsequently, natural frequency equations are derived on the basis of energy conservation principle. The effect of axial forces on natural frequency is also considered in the proposed formulas. Using the method presented in this study, natural frequencies are computed using a simplified method with no complex numerical modeling. The proposed formulas are verified via experimental and numerical methods. Close agreement between the results from these three approaches are observed. Furthermore, the effects of panel zone flexibility, continuity plates and doubler plates on the natural frequencies of buildings are investigated.  相似文献   

Field monitoring of railroad embankment vibration responses in seasonally frozen regions     

ZiYu Wang  XianZhang Ling  Feng Zhang  LiNa Wang  ShiJun Chen  ZhanYuan Zhu 《寒旱区科学》2013,5(4):0393-0398

To investigate the vibration characteristics of a railway subgrade in different seasons, three field experiments were carried out in the seasonally frozen Daqing area of China during spring, summer, and winter. The vibration characteristics and attenuation rates of the subgrade induced by passing trains were investigated, and the influences of the season, train speed, train type, train load, and number of train compartments are described in this paper. The results show that: (1) near the rail track the vibration in the vertical direction was more significant than in the lateral and longitudinal directions, and as the distance from the railway track increased, the acceleration amplitudes and the attenuation rates all decreased in all three directions; (2) the acceleration amplitudes and attenuation rates decreased in the three different study seasons as the distance from the railway track increased, and the attenuation rates in the freezing period were the largest; and (3) the acceleration amplitude induced by a freight train was greater than that by a passenger train, and the subgrade vibration increased with increasing passenger train speeds when the number of train compartments was similar. These results have great significance for enhanced understanding of the characteristics of train-induced vibration embankment response in seasonally frozen regions, and provide essential field monitoring data on train-induced vibrations in order to improve the performance criteria of railroading in seasonally frozen regions.  相似文献   

Vertical impedance of an end‐bearing pile in viscoelastic soil          下载免费PDF全文

Changjie Zheng  Xuanming Ding  Ping Li  Qiang Fu 《国际地质力学数值与分析法杂志》2015,39(6):676-684

This paper presents a new method to derive the analytical solution for the vertical impedance of an end‐bearing pile in viscoelastic soil. The soil is assumed as a homogeneous and isotropic layer, and the pile is considered as a one‐dimensional Euler rod. Considering both the vertical and radial displacements of soil and soil–pile coupled vibration, the governing equations of the soil and pile are established. The volumetric strain of soil is obtained by transformation on the equations of soil and variable separation method. Then the vertical and radial displacements of soil are obtained accordingly. The displacement response and impedance function of pile are derived based on the continuity assumption of the displacement and stress between the pile and soil. The solution is verified by being compared with an existing solution obtained by introducing potential functions. Furthermore, a comparison with two other simplified solutions is conducted. Numerical examples are presented to analyze the vibration characteristics of the pile. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Rocking vibration of a rigid circular disc in a transversely isotropic full‐space     

Morteza Eskandari‐Ghadi  Ammar Mirzapour  Azizollah Ardeshir‐Behrestaghi 《国际地质力学数值与分析法杂志》2011,35(14):1587-1603

In this paper, forced rocking vibration of a rigid circular disc placed in a transversely isotropic full‐space, where the axis of material symmetry of the full‐space is normal to the surface of the plate, is analytically investigated. Because of using the Fourier series and Hankel integral transforms, the mixed boundary‐value problem is transformed into two separate pairs of integral equations called dual integral equations. The dual integral equations involved in this paper are reduced to Fredholm integral equations of the second kind. With the aid of contour integration, the governing integral equation is numerically evaluated in the general dynamic case. The reduced static case of the dual integral equations is solved analytically and the vertical displacement, the contact pressure and the static impedance/compliance function are explicitly determined, and it is shown that the pressure in between the plate and the full‐space and the compliance function reduced for isotropic half‐space are identical to the previously published solutions. The dynamic contact pressure in between the disc and the space and also the related impedance function are numerically evaluated in general dynamic case and illustrated. It is shown that the singularity exists in the contact pressure at the edge of the disc is the same as the static case. To show the effect of material anisotropy, the numerical evaluations are given for some different transversely isotropic materials and compared. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

桥塔涡激共振可靠性简化计算方法     

周宝勇  余建星  郭君  周清基 《地震工程与工程振动》2011,31(4):127-131

针对桥塔在风载荷下的涡激共振可靠性问题,在涡激振动机理与频率锁定现象研究基础上,提出一种计算桥塔涡激振动可靠性的简化方法.将临界风速结合Re数和Strouhal数建立涡激共振下桥塔安全裕度方程,并引入AFOSM求解方法解决非线性问题,利用MATLAB进行可靠性求解程序编制,在保证计算精度的同时大大降低了桥塔涡激振动可靠...  相似文献