共查询到19条相似文献，搜索用时 156 毫秒
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根据系统能量，由拉格朗日方程导出多层地基-非线性结构系统地震响应分析的动力方程，利用突变模型分析了系统地震响应的分叉和突变特性，讨论了振幅响应的跳跃现象和”路径”效应等非线性动力特性以及地基参数对分叉集和突变性质的影响，得出了对地基-结构动力系统设计有一定参考价值的结论。 相似文献
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有限观测信息下的参数识别是结构健康监测领域内的一个热点问题,传统的卡尔曼滤波(Kalman Filter,KF)不能识别结构参数,递推最小二乘法(Recursive Least Square Estimation,RLSE)可用于参数识别,但需已知结构全部响应,为此提出一种基于KF和RLSE的参数联合识别法,该方法首先利用部分自由度上的加速度响应观测值,通过KF估计下一步的系统响应信息,包括速度和位移响应;然后,基于该响应估计信息和当前步的结构参数估计值,根据运动平衡方程,获得下一步的加速度响应估计值;最后,利用已观测的有限加速度响应,获得改进的加速度响应向量,进而基于RLSE获得下一步的结构参数识别值。简支梁数值算例结果表明,该方法能准确识别结构参数,同时能实现系统响应的有效估计。 相似文献
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单跨简支梁竖向振动的磁悬浮半主动控制 总被引：1，自引：0，他引：1
由于传统的隔振器需要足够的竖向刚度来支撑上部结构,因而不能隔离竖向振动。为了解决这一问题,本文提出一种新的隔振策略,即磁浮式半主动控制方法,并将这一方法应用于弹性梁弯曲振动的半主动控制。将均质弹性梁简化为一带集中质量的简支梁,导出了控制系统的运动方程,讨论了系统在平衡点的稳定性,应用推广的Runge-Kutta方法,得到了系统在随机地面输入下的加速度响应。结果表明：杆件的初始悬浮位置是磁浮式半主动控制系统的平衡点,且平衡点是L稳定的;磁浮式半主动隔振系统具有类似于软弹簧的性质,与普通的弹性简支梁相比,磁浮式半主动振动控制系统的振动频率较低,加速度响应明显减小,系统具有良好的竖向隔振性能。 相似文献
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地震作用下参数不确定系统的变结构控制 总被引：5，自引：2，他引：3
本文对结构参数具有有确定性的变结构控制系统设计方法进行了研究。首先采用摄动方法给出了结构参数具有确定性的控制系统的运动方程,证明了基于层间剪切模型的参数不确定受控系统与其标称系统具有相同的滑动模态,从而解决了系统切换函数的确定问题,并利用到达条件推导了控制律的表示式。算例分析结果表明,本文的控制方法能有效地减小结构的地震响应,对于结构系统建模存在误差或系统本身存在学确定性的情况,控制效果仍十分显著 相似文献
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基于我国现行的风荷载规范,建立了在风荷载作用下结构-主动调谐质量阻尼器(ATMD)系统的动力方程。定义ATMD最优参数准则为:结构-ATMD系统的位移或加速度响应方差的最小化。ATMD有效性的评价准则为:设置ATMD结构的最小化位移或加速度响应方差与未设置ATMD结构的位移或加速度响应方差之比(分别称为位移和加速度减振系数)。根据上述准则,在频域内数值研究了结构自振频率、标准化加速度反馈增益系数、质量比对ATMD系统的最优参数(包括最优频率比和阻尼比)、有效性和冲程的影响。此外,为了比较的目的,论文同时考虑了结构TMD风致振动控制的情况。 相似文献
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基础隔震结构随机地震响应分析的复模态法 总被引：13，自引：1，他引：13
本文对多自由度基础隔震结构的随机地震响应问题进行了系统研究，首先建立了运动方程，然后用第一振型将上部结构展开，针对所得方程为非经典阻尼、非对称质量和非对称刚度情况，用复模态法解耦，获得了以第一振型表示的结构地震响应的解析解，对单自由度体系，此解即为结构响应的精确解，从而建立了两自由度体系在任意非经典阻尼与非对称质量和刚度情况下随机地震响应解析解分析的一般方法。本文方法也可用于带TMD减震结构、无损伤“加层减震”加固结构的随机地震响应分析与优化设计。 相似文献
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将梁简化为两端简支的欧拉-伯努利梁模型,桥墩简化为底部固结的柱,考虑两自由度车辆移动系统与桥面结构表面接触处不平整产生的随机激励,建立了移动车辆系统-桥-墩的耦合力学分析模型。根据子结构方法和演变随机过程一般理论,并应用模态分析法对车-桥-墩耦合系统进行随机振动分析,推导得到了桥墩位移、桥墩轴力、梁竖向位移协方差函数和均方值响应的理论计算公式。通过数值算例,比较了跨中位移的确定性响应和跨中位移的均方根值响应,讨论了在不同桥墩高度、不同车辆移动速度、不同桥面等级下桥梁跨中竖向位移均方根、桥墩轴力均方根的变化规律。 相似文献
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TMD抑制桥梁振动仿真分析 总被引：1，自引：0，他引：1
分别建立简支梁和调谐质量阻尼器（TMD）的运动方程,并采用振型叠加法建立与其对应的广义坐标方程,同时结合现代控制理论,采用状态空间法建立与其对应的状态方程,运用SIMULINK仿真系统对简支梁桥进行了动力仿真分析。首先对未布置TMD的系统进行了仿真分析,并与Newmark—β法编程计算的结果对比,两种方法的计算结果十分接近,说明了SIMULINK方法的准确性;在此基础上,对布置TMD的桥梁进行了分析,通过分析TMD参数对减振效果的影响,进行了动力学解释,所得出的优化参数,可供工程控制参考。 相似文献
10.
随机结构分析的扩阶系统方法（II）结构动力分析 总被引：2，自引：0，他引：2
李杰 《地震工程与工程振动》1995,15(4):27-35
本文论述随机结构系统在确定性时程激励下的分析方法。文中提供的扩阶系统动力方程的一般公式，适用于同时具有随机质量、随机阻尼、随机刚度参数的多自由度动力系统。文中并对此扩阶动力方程建议了基于线性加速度假定的递归聚缩算法。 相似文献
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This paper explores dynamic soil–bridge interaction in high speed railway lines. The analysis was conducted using a general and fully three-dimensional multi-body finite element–boundary element model formulated in the time domain to predict vibrations caused by trains passing over the bridge. The vehicle was modelled as a multi-body system, the track and the bridge were modelled using finite elements and the soil was considered as a half-space by the boundary element method. The dynamic response of bridges to vehicle passage is usually studied using moving force and moving mass models. However, the multi-body system allows to consider the quasi-static and dynamic excitation mechanisms. Soil–structure interaction was taken into account by coupling finite elements and boundary elements. The paper presents the results obtained for a simply supported short span bridge in a resonant regime under different soil stiffness conditions. 相似文献
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混凝土桥梁在工作过程中会产生裂缝，为分析移动荷载对开裂混凝土桥梁结构刚度的影响，对开裂梁动力响应进行分析。建立简支T梁桥有限元模型，并将移动荷载施加至有限元模型中。根据简支T梁桥破坏横向分布位置和强度的不同，研究不同工况下各梁荷载横向分布及不同移动速度对裂缝扩展宽度的影响。结果表明，数值模拟结果能较好地验证计算模型的准确性；在较大的移动荷载作用下，混凝土开裂，导致结构刚度减小、位移增大；随着移动荷载和速度的增加，开裂时间增加，结构刚度降低，持续时间增加，位移增大，使结构响应呈现明显非线性。 相似文献
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J. W. Smith 《地震工程与结构动力学》1972,1(4):357-370
This paper presents a method of analysis for the dynamic response of a simply supported beam and slab bridge under the action of a moving vehicle. The bridge is idealized as an orthotropic plate and, in the analysis, is subdivided into a number of finite strips. The vehicle is idealized as a moving sprung mass. Viscous damping is taken into account for both bridge and vehicle. The results show that there is significant variation of response across transverse sections of the bridge. Furthermore the dynamic magnification is considerably greater than that predicted by a more approximate method in which the bridge is idealized as a simple prismatic beam. 相似文献
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The objective of this research is to study the dynamic response characteristics of a three-beam system with intermediate elastic connections under a moving load/mass-spring. In this study, the finite Sine-Fourier transform was performed for the dynamic partial differential equations of a simply supported three-beam system (SSTBS) under a moving load and a moving mass-spring, respectively. The dynamic partial differential equations were transformed into dynamic ordinary differential equations relative to the time coordinates, and the equations were solved and the displacement Fourier amplitude spectral expressions were obtained. Finally, based on finite Sine-Fourier inverse transform, the expressions for dynamic response of SSTBS under the moving load and moving mass-spring were obtained. The proposed method, along with ANSYS, was used to calculate the dynamic response of the SSTBS under a moving load/mass-spring at different speeds. The results obtained herein were consistent with the ANSYS numerical calculation results, verifying the accuracy of the proposed method. The influence of the load/mass-spring’s moving speed on the dynamic deflections of SSTBS were analyzed. SSTBS has several critical speeds under a moving load/mass-spring. The vertical acceleration incurred by a change in the vertical speed of SSTBS due to the movement of mass-spring and the centrifugal acceleration produced by the movement of massspring on the vertical curve generated by SSTBS vibration could not be neglected. 相似文献
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汶川大地震简支梁桥落梁震害与设计对策 总被引：2，自引：0，他引：2
总结了5.12汶川大地震中简支梁桥落梁震害及主要影响因素,发现除地震山体滑坡等地质灾害外,断层地表破裂、近断层地震动效应、桥台胸墙冲切破坏、防落梁构造措施单一及桥梁体型复杂等因素都是引起简支梁桥落梁震害的重要原因。提出了简支梁桥防落梁设计的基本理念及相关技术方案要点为允许墩梁间发生滑移,以降低桥墩承受的地震惯性力,以及盖梁提供允许的最大滑移长度及支座支承宽度,再辅助挡块或拉索限位器等共同防止落梁发生。最后结合现行规范,以拉索限位器为例给出了简支梁桥防落梁设计方法。 相似文献
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In this paper a general dynamic analysis of a foundation beam on Green-Boussinesq soil is performed, taking into account the instabilizing effect of conservative and nonconservative applied axial loads.The beam is reduced to a finite number of rigid bars, linked together by elastic springs; the equations of motion are written by means of the Lagrange equations. The kinetic energy and the total potential energy are calculated first, and emphasis is placed on the strain energy of the Green soil; then the virtual work of the applied follower loads is detected, which allow us to define the generalized forces. The resulting equations of motion lead to an eigenvalue problem with unsymmetric matrix.Initially, the first free vibration frequencies of simply supported beams, clamped beams and free beams are plotted as functions of the two soil parameters. A more complex beam is also examined, in order to show the method potentialities. A stability analysis in the presence of conservative axial loads is then performed, and the influence of the soil on the critical load is discussed, both for simply supported beams and clamped beams. Finally, the instability mechanism of a clamped - clamped beam subjected to a uniformly distributed follower force is shown to be deeply influenced by the presence of the soil. (A number of graphs and examples conclude the paper.) 相似文献
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A numerical method is shown to analyse the dynamic elastic-plastic responses of those structures with known elastic solutions. The displacement at one point at time t caused by a unit load applied at another point at zero time, called dynamic influence coefficient, is calculated from the known elastic solutions. Incremental plastic strain is accounted for by a set of additional incremental loads, so the stiffness matrix and the eigenvectors do not vary with time. From the incremental load including that caused by the incremental plastic strain, the displacement vs. time of the structure is obtained. This method is applied to simply supported beams with bilinear stress-strain relations with different strain-hardening rates and to a simply supported elastic-ideally plastic rectangular plate. This procedure can be extended to structures with no available known analytical elastic solutions. For these structures, the elastic solutions can be obtained by the finite element method. 相似文献
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Optimum absorber parameters for simple systems 总被引：1，自引：0，他引：1
In the classical problem a damped one degree-of-freedom absorber system is attached to a main system, which has one degree of freedom and is undamped. The optimum values of absorber stiffness and damping, which will minimize the resonant response of the main mass, are well known. In this paper the effect on these optimum conditions of light damping in the main system is studied. The authors show that optimum parameters for absorbers, which are attached to beams and plates, can be obtained simply and accurately from those for an equivalent one degree-of-freedom main system. This depends upon the concept of an effective mass for the elastic body and the representation of its response by the single relevant mode. It will be shown in a later paper that for more complex elastic bodies such as cylindrical shells, for which the natural frequencies are more closely spaced, these simple concepts do not predict accurately optimum absorber parameters. 相似文献