考虑耦联影响的二次结构体系减震分析

建立了基础隔震的主次结构体系耦联运动方程,开发了动力分析程序PS—BASE．FOR,对一典型结构的二次结构绝对加速度反应谱与相对位移反应谱计算分析表明,主体结构隔震或同时增大二次结构阻尼,是取得二次结构较好抗震性能的有效途径,增大主体结构的隔震阻尼对二次结构略有不利影响。     

楼板隔震消能结构体系

提出了一种新型减震结构体系——楼板隔震消能结构体系。该结构体系的特点是:竖向荷载传递途径与传统结构相同,但在楼板与主体结构水平承重构件之间设置高阻尼隔震层,在楼板与主体结构竖向承重构件之间留出空隙,并在其中安装消能阻尼器,使结构在发生水平振动时楼板与主体结构之间能够发生一定的相对运动,产生隔震和消能作用,减小结构的地震反应。本文给出了单层楼板隔震消能结构的运动微分方程,以及基底输入谐和振动时的结构传递函数,并分析了结构参数对传递函数的影响。     

隔震减震主次结构体系非线性随机地震反应分析

为研究隔震、减震装置非线性恢复力特性对2自由度主次结构体系均方根位移反应的影响规律,以隔震、减震装置微分型恢复力模式的滞回参数为变量,地震地面运动模拟成高斯白噪声过程,利用等效线性化方法得到主体结构和二次结构均方根位移反应的表达式.分析表明,主体结构隔震装置非线性恢复力特征对主、次结构的均方根位移反应的影响占主导地位;隔震、减震装置的恢复力特征产生适度非线性有利于减小主、次结构的均方根位移反应.     

结构减震隔震设计最优化问题研究

针对结构抗震减震隔震设计结构动力学基本方程,进行了基本结构刚度、阻尼和质量三方面减震隔震设计问题特征分析,专门指出刚度和阻尼的减震隔震设计研究已经有规范规定,但对减轻结构质量的减震隔震设计仍是需要深入研究的创新问题。目前采用新材料进行设施农业结构减震隔震设计,特别是采用玄筋混凝土现代无金属结构进行结构抗震减震隔震设计,结构最优化设计的实现便有了新契机,且容易实现抗力均匀分布,将较为彻底地解决地震工程的最优结构抗震问题。     

连接区独立的多点支撑二次结构抗震分析

目前多点支撑二次结构地震响应分析把连接构件并人二次结构，假定与二次结构具有相同阻尼，与工程实际大多不符，存在一定近似，也不宜直接用来进行二次结构减振分析。为此提出将连接构件独立于二次结构考虑，采用具有连接区的混合子结构模态综合法分析主次结构地震响应，分析连接构件刚度、阻尼的变化对二次结构地震响应的影响，对连接构件合适的刚度与阻尼参数进行了讨论。     

日本建筑结构隔震减震研究新进展

本文介绍了日本在建筑结构隔震，减震研究方面取得的几项新进展，其中基础隔震板片结构体系是一种新型隔震结构体系，纳米结晶锌铝合金振动控制阻尼器是一种取得专利的新型减震阻尼器，无粘结钢支撑体系是一种比较新颖的减震支撑体系，跷摆振动控制设计是一个新颖的减震设计概念。     

隔震结构"小震不坏"的动力可靠度分析

本文探讨叠层橡胶隔震体系在“小震不坏”条件下的动力可靠度分析。基于等效线性化的隔震工程设计参数,建立非比例阻尼隔震结构模型。采用双过滤白噪声功率谱模型描述地震动,并用林家浩虚拟激励法进行随机响应分析。以各层的最大层间位移响应作为控制指标,取结构的弹性位移限值作为位移极限值,建立功能状态方程。根据一次二阶矩方法,用串联模式计算体系的总体可靠度。文末选用了一个7层隔震框架作为数值算例,探讨了隔震阻尼、寒冷环境、节点构造误差所引起的隔震层刚度上升,以及场地土类别等对体系动力可靠性的影响。     

基于柱顶隔震的3层3跨地铁地下车站结构抗震性能研究

针对3层3跨框架式地铁地下车站结构抗震薄弱构件,采用在柱顶不同位置设置铅芯橡胶隔震支座的方法,建立土-地下连续墙-主体结构非线性静动力耦合相互作用的二维整体时域有限元分析模型,分析柱顶隔震支座对车站主体结构的侧向变形、地震损伤和动应力反应等结构地震反应特性的影响.结果表明,仅在抗震薄弱的顶层和底层中柱柱顶设置2层隔震支...     

基础隔震结构考虑摆动的振动控制研究

在基础隔震结构中,当上部结构层间刚度相对较小、垂直荷载较大,且采用的叠层橡胶垫的橡胶总厚度较大时,隔震支座不仅要产生水平变形,同时也会产生竖向变形,导致上部结构产生摆动.文中推导了基础隔震结构考虑摆动的运动和控制方程,分析研究了摆动对基础隔震结构的振动控制影响.研究结果表明:基础隔震结构的摆动对控制有一定影响;隔震层转动刚度、阻尼和上部结构垂直荷载对基础隔震结构考虑摆动的振动控制有明显影响.     

结构偏心对基础隔震结构地震反应的影响

本文对基础隔震偏心结构在不同场地上的地震动作用下的反应进行了深入研究，探讨了上部结构偏心、隔震层偏心、场地条件等因素对于基础隔震结构地震反应的影响，选取了能反映结构偏心特性的参数，以便将分析各因素对隔震结构地震反应的影响转化为分析参数的影响。通过大量的数值计算与分析，得到了一些对实际工程有意义的结论。     

Fuzzy logic control of bridge structures using intelligent semi-active seismic isolation systems

Passive supplemental damping in a seismically isolated structure provides the necessary energy dissipation to limit the isolation system displacement. However, damper forces can become quite large as the passive damping level is increased, resulting in the requirement to transfer large forces at the damper connections to the structure which may be particularly difficult to accommodate in retrofit applications. One method to limit the level of damping force while simultaneously controlling the isolation system displacement is to utilize an intelligent hybrid isolation system containing semi-active dampers in which the damping coeffic ient can be modulated. The effectiveness of such a hybrid seismic isolation system for earthquake hazard mitigation is investigated in this paper. The system is examined through an analytical and computational study of the seismic response of a bridge structure containing a hybrid isolation system consisting of elastomeric bearings and semi-active dampers. Control algorithms for operation of the semi-active dampers are developed based on fuzzy logic control theory. Practical limits on the response of the isolation system are considered and utilized in the evaluation of the control algorithms. The results of the study show that both passive and semi-active hybrid seismic isolation systems consisting of combined base isolation bearings and supplemental energy dissipation devices can be beneficial in reducing the seismic response of structures. These hybrid systems may prevent or significantly reduce structural damage during a seismic event. Furthermore, it is shown that intelligent semi-active seismic isolation systems are capable of controlling the peak deck displacement of bridges, and thus reducing the required length of expansion joints, while simultaneously limiting peak damper forces. Copyright © 1999 John Wiley & Sons, Ltd.     

Seismic response of light internal equipment in base-isolated structures

The seismic response of light secondary systems in a building is dependent on the response of the primary structural system to the seismic ground motion with the result that very high accelerations can be induced in such secondary systems. This response can be reduced through the use of aseismic base isolation which is a design strategy whereby the entire building can be decoupled from the damaging horizontal components of seismic ground motion by the use of some form of isolation system. The paper presents a theoretical analysis of the response of light equipment in isolated structures and a parallel experimental programme both of which show that the use of base isolation can not only attenuate the response of the primary structural system but also reduce the response of secondary systems. Thus, the design of equipment and piping in a base-isolated building is very much simpler than that for a conventionally founded structure: inelastic response and equipment-structure interaction need not be considered and multiple support response analysis is rendered unnecessary. Although an isolation system with linear elastic bearings can reduce the acceleration of the structure, it may be accompanied by large relative displacements between the structure and the ground. A system using lead-rubber hysteretic bearings, having a force-displacement relation which is approximately a bilinear loop, can reduce these displacements. A parallel experimental programme was carried out to investigate the response of light equipment in structures isolated using lead-rubber bearings. The experimental results show that these bearings can dissipate energy and limit the displacement and acceleration of the structure but are less effective in reducing the accelerations in the internal equipment. The results of both the analysis and the tests show that base isolation is a very effective method for the seismic protection of light equipment items in buildings.     

相邻结构连接阻尼器的最优设计参数

本文通过Maxwell模型模拟的黏滞阻尼器连接的2种不同相邻结构的地震反应分析,对阻尼器设置的位置和阻尼参数进行了同时优化。在El Centro波、Tianjin波和Taft波3种较典型的地震动作用下,分别对不同质量比和不同刚度比的主、子结构在无阻尼和有阻尼情况下进行了地震反应分析,并以主结构的顶层最大相对位移最小作为优化目标,寻求出最优的阻尼器摆放位置以及对应的最优阻尼系数。结果显示,当阻尼器选择合适的安放位置和合理的阻尼参数时,主、子结构的地震反应都会有一定程度的降低,从而收到较好的减震效果。     

导管架式海洋平台结构阻尼隔振体系及其减振效果分析

导管架式海洋平台结构是当前应用最广的一种平台结构形式。本文研究导管架式海洋平台结构阻尼隔振体系及其减振效果。针对导管架式海洋平台结构的型式与特点，为了充分发挥阻尼器的耗能减振作用，提出了在平台结构导管架端帽和甲板之间设置柔性阻尼层的新型阻尼隔振方案。针对渤海JZ20－2MUQ平台结构，建立了海洋平台结构阻尼隔振体系简化计算模型，研究了隔振层参数与结构阻尼比的关系以及它们对结构整体和隔振层层间相对位移的控制效果；进行了多种冰荷载工况和地震工况的数值模拟。结果表明，阻尼隔振方案是导管架式海洋平台结构的一种有效的减振措施。     

Non-classical damping in dynamic analysis of base-isolated structures with internal equipment

It has been shown that the use of base isolation not only attenuates the response of a primary structural system but also reduces the response of a secondary system mounted on or within the main structure. The isolation system, superstructure and equipment may be made of different materials with significantly different energy dissipation characteristics such that the damping matrix for the combined system is non-classical and can only be approximately expressed by modal damping ratios if the classical mode method is used for analysis. The object of this paper is to evaluate the accuracy of this procedure in approximating the responses of base-isolated structures and internal equipment. The complex mode method can provide exact solutions to problems with non-classical damping and is used here to find the exact response of the isolation-superstructure-equipment system. The entire system is assumed to be linear elastic with viscous damping and the superstructure is assumed to be proportionally damped so that the deformation of the superstructure can be expressed in terms of its classical modes. Recognizing that the ratio of the equipment mass to the structural mass and the ratio of the stiffness of the isolation system to the superstructural stiffness are both small, perturbation methods are used to find the response. This study shows that the response of base-isolated structures can be determined by the classical mode method to some degree of accuracy, but the higher frequency content is distorted. The equipment response derived by the classical mode method is much smaller than the exact solution so that the complex mode method should be applied to find equipment response.     

The role of viscoelastic damping on retrofitting seismic performance of asymmetric reinforced concrete structures

The primary purpose of this research is to improve the seismic response of a complex asymmetric tall structure using viscoelastic(VE) dampers. Asymmetric structures have detrimental effects on the seismic performance because such structures create abrupt changes in the stiffness or strength that may lead to undesirable stress concentrations at weak locations. Structural control devices are one of the effective ways to reduce seismic impacts, particularly in asymmetric structures. For passive vibration control of structures, VE dampers are considered among the most preferred devices for energy dissipation. Therefore, in this research, VE dampers are implemented at strategic locations in a realistic case study structure to increase the level of distributed damping without occupying significant architectural space and reducing earthquake vibrations in terms of story displacements(drifts) and other design forces. It has been concluded that the seismic response of the considered structure retrofitted with supplemental VE dampers corresponded well in controlling the displacement demands. Moreover, it has been demonstrated that seismic response in terms of interstory drifts was effectively mitigated with supplemental damping when added up to a certain level. Exceeding the supplemental damping from this level did not contribute to additional mitigation of the seismic response of the considered structure. In addition, it was found that the supplemental damping increased the total acceleration of the considered structure at all floor levels, which indicates that for irregular tall structures of this type, VE dampers were only a good retrofitting measure for earthquake induced interstory deformations and their use may not be suitable for acceleration sensitive structures. Overall, the research findings demonstrate how seismic hazards to these types of structures can be reduced by introducing additional damping into the structure.     

Optimal damping between two adjacent elastic structures

The optimal values for the distribution of passive dampers interconnecting two adjacent structures of different heights are determined. The dampers are selected to minimize the seismic response in the first and second modes of the taller of the two structures. For simplicity, the structures are represented as uniform damped shear beams subjected to a common ground motion. Under certain conditions, apparent damping ratios as high as 12 and 15 per cent can be achieved in the first and second modes of lightly damped structures by the introduction of interconnection dampers. The largest reduction of the response in the first mode is achieved when the taller structure is about twice the height of the second structure. © 1998 John Wiley & Sons, Ltd.     

Effect of viscous damping devices on the response of seismically isolated structures

Viscous and other damping devices are often used as elements of seismic isolation systems. Despite the widespread application of nonlinear viscous systems particularly in Japan (with fewer applications in the USA and Taiwan), the application of viscous damping devices in isolation systems in the USA progressed intentionally toward the use of supplementary linear viscous devices due to the advantages offered by these devices. This paper presents experimental results on the behavior of seismically isolated structures with low damping elastomeric (LDE) and single friction pendulum (SFP) bearings with and without linear and nonlinear viscous dampers. The isolation systems are tested within a six‐story structure configured as moment frame and then again as braced frame. Emphasis is placed both on the acquisition of data related to the structural system (drifts, story shear forces, and isolator displacements) and on non‐structural systems (floor accelerations, floor spectral accelerations, and floor velocities). Moreover, the accuracy of analytical prediction of response is investigated based on the results of a total of 227 experiments, using 14 historic ground motions of far‐fault and near‐fault characteristics, on flexible moment frame and stiff braced frame structures isolated with LDE or SFP bearings and linear or nonlinear viscous dampers. It is concluded that when damping is needed to reduce displacement demands in the isolation system, linear viscous damping results in the least detrimental effect on the isolated structure. Moreover, the study concludes that the analytical prediction of peak floor accelerations and floor response spectra may contain errors that need to be considered when designing secondary systems. Copyright © 2014 John Wiley & Sons, Ltd.     

Seismic response of simple structures using spring-assisted sliding slabs with coulomb damping

Coulomb damping can be utilized effectively to reduce the dynamic response of structures subjected to seismic ground motions. To activate this damping, some parts of a vibrating structure are allowed to slide at rough interfaces. The dynamic response of structures provided with sliding interfaces at the base, between a floor slab and frame and in the cross bracings of a frame has been examined recently. In this paper, a simple slab sliding system provided with a spring to introduce a recovery mechanism and to reduce the sliding displacement requirement for low frequency structures has been examined. The equations of motion for this system are developed. An approach is presented to solve these coupled equations for earthquake induced ground motions. Structures with varying frequency and friction characterisics are considered and the numerical results are presented in response spectrum form. It is observed that, in low frequency structures, provision of a rather weak spring can reduce the sliding displacement requirements without significantly increasing the forces in the supporting frame and the acceleration input to supported secondary systems.