共查询到19条相似文献，搜索用时 125 毫秒
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本文基于积函数极值法，对刚度分布未确知的连续拱桥的墩顶地震位移上限进行了识别。文中研究了两跨、三跨、任意奇数跨和任意偶数跨等各种情形，对简化模型作了精度分析，并将所识别的上限值与实际计算反应值进行了比较。 相似文献
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基础动力刚度的精确数值解及集中参数模型 总被引：2，自引：1，他引：2
土－结构相互作用分析的关键是建立以土－结构界面定义的无限半空间的动力刚度矩阵。本文介绍了一种求解半无限地基动力刚度的新方法，通过两个算例验证了该方法的精度，并给出了一种利用频域刚性基础动力刚度计算基础时域荷载响应的实用方法，该研究为刚性基础设计提供了一种新的，可靠的理论方法。 相似文献
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空间钢筋混凝土框架结构的非弹性地震反应 总被引：3，自引：0，他引：3
对两个缩比为十五分之一的三层、双跨、两开间的钢筋混凝土框架模型进行了振动台试验,一个模型模拟质量中心与刚度中心不一致的偏心结构,另一个模型模拟承受双向地面运动的结构。研究了结构的空间非弹性地震反应。计算结果表明,理论分析与实测结果有较好的吻合性。 相似文献
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低周反复荷载下方钢管混凝土框架抗震性能的试验研究 总被引：19，自引：3，他引：19
通过对一榀两跨三层的方钢管混凝土组合框架在低周反复荷载作用下的模型试验，深入研究了方钢管混凝土组合框架的滞回性能、延性、耗能能力和刚度退化等抗震性能。研究结果表明：方钢管混凝土结构的抗震性能优于混凝土结构。 相似文献
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本文利用ABAQUS有限元分析软件,对双向水平往复荷载作用下的钢筋混凝土核心筒进行非线性分析,将所得结果与现有试验结果对比验证,明确了其破坏形态、承载力、刚度退化和耗能能力等抗震性能。研究结果表明,两个方向受力的耦合作用会导致刚度退化的加剧,降低其抗震性能;通过分析轴压比、连梁跨高比和截面长宽比等参数,并与单向加载下的结果对比,发现轴压比和连梁跨高比均是影响筒体破坏形态的重要因素,且两个方向的刚度差异则会导致筒体变形能力与延性有较大的降低;给出了考虑加载方式、洞口大小以及混凝土强度影响的核心筒在压、弯、剪、扭复合状态下的承载力计算公式,并与现有试验结果对比,吻合较好。 相似文献
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排架支承式渡槽自振频率的简化计算方法 总被引：1，自引：0，他引：1
本文对于排架支承式渡槽自振频率的简化计算方法进行了研究，对于竖向力、柱和横梁的刚度的相对变化对结构自振频率的影响也进行了研究，从研究结果可发现随着竖向力的增加该结构的自振频率逐渐降低，柱和横梁的刚度的相对变化对于结构的自振频率有比较大的影响。本文的研究成果可为渡槽结构的设计计算提供了参考依据。 相似文献
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沿高变刚度设支撑高层大开间异型柱框架抗震性能试验研究 总被引：2，自引：0，他引：2
提出了沿异型住框架楼层变刚度设支撑的设计方法,进行了1／3结构模型试验研究,测试分析了弹性侧移刚度、结构的承载力、延性、滞回曲线、破坏机制及刚度衰减特性。计算所得的结构弹性侧移刚度与实测值符合较好． 相似文献
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This paper presents an experimental study to investigate the performance of shape memory alloy(SMA) restrainers for mitigating the pounding and unseating of highway bridges when subjected to seismic excitations.Mechanical property tests of the SMA wire used in the restrainers are conducted first to understand the pseudo-elastic characteristics of the material.Then,a series of shaking table tests are carried out on a highway bridge model.The structural responses of the highway bridge model equipped with SMA restrainers,installed in the form of deck-deck and deck-pile connections,are analyzed and compared with the uncontrolled structures.The test results of this study indicate that the SMA restrainers are not only effective in preventing unseating but also in suppressing the seismic-induced pounding of the highway bridge model used in this study. 相似文献
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Energy dissipating restrainers for highway bridges 总被引：1，自引：0，他引：1
Recent destructive earthquakes have demonstrated the vulnerability of highway bridges to collapse due to excessive movement beyond the available seat widths at expansion joints. This paper investigates the efficacy of using energy dissipating restrainers at expansion joints for preventing collapse of highway bridges in the event of a severe earthquake. The restrainer consists of a nonlinear viscous damper and an elastic spring connected in parallel or in series. Two-dimensional finite element analysis using bilinear hysteretic models for bridge substructure joints and nonlinear gap elements for expansion joints is performed on example bridges with one or two expansion joints. The analytical study demonstrates that the energy dissipating restrainers are effective in reducing the relative opening displacements and impact forces due to pounding at the expansion joints, without significantly increasing ductility demands in the bridge substructures. 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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Seismic pounding between adjacent frames in multiple-frame bridges and girder ends in multi-span simply supported bridges has been commonly observed in several recent earthquakes. The consequences of pounding include damage to piers, abutments, shear keys, bearings and restrainers, and possible collapse of deck spans. This paper investigates pounding in bridges from an analytical perspective. A simplified nonlinear model of a multiple-frame bridge is developed including the effects of inelastic frame action and nonlinear hinge behavior, to study the seismic response to longitudinal ground motion. Pounding is implemented using the contact force-based Kelvin model, as well as the momentum-based stereomechanical approach, Parameter studies are conducted to determine the effects of frame period ratio, column hysteretic behavior, energy dissipation during impact and near source ground motions on the pounding response of the bridge. The results indicate that pounding is most critical for highly out-of-phase frames and is not significant for frame period ratios greater than 0.7. Impact models without energy dissipation overestimate the displacement and acceleration amplifications due to impact, especially for elastic behavior of the frames. Representation of stiffness degradation in bridge columns is essential in capturing the accurate response of pounding frames subjected to far field ground motion. Finally, it is shown that strength degradation and pounding can result in significant damage to the stiffer frames of the bridge when subjected to large acceleration pulses from near field ground motion records. 相似文献
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Implications of seismic pounding on the longitudinal response of multi-span bridges - an analytical perspective 总被引：2，自引：0，他引：2
ReginaldDesRoches SusendarMuthukumar 《地震工程与工程振动(英文版)》2004,3(1):57-65
Seismic pounding between adjacent frames in multiple-frame bridges and girder ends in multi-span simply supported bridges has been commonly observed in several recent earthquakes. The consequences of pounding include damage to piers, abutments, shear keys, bearings and restrainers, and possible collapse of deck spans. This paper investigates pounding in bridges from an analytical perspective. A simplified nonlinear model of a multiple-frame bridge is developed including the effects of inelastic frame action and nonlinear hinge behavior, to study the seismic response to longitudinal ground motion. Pounding is implemented using the contact force-based Kelvin model, as well as the momentum-based stereomechanical approach. Parameter studies are conducted to determine the effects of frame period ratio, column hysteretic behavior, energy dissipation during impact and near source ground motions on the pounding response of the bridge. The results indicate that pounding is most critical for highly out-of-phase frames and is not significant for frame period ratios greater than 0.7. Impact models without energy dissipation overestimate the displacement and acceleration amplifications due to impact, especially for elastic behavior of the frames. Representation of stiffness degradation in bridge columns is cssential in capturing the accurate response of pounding frames subjected to far field ground motion. Finally, it is shown that strength degradation and pounding can result in significant damage to the stiffer frames of the bridge when subjected to large acceleration pulses from near field ground motion records. 相似文献
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Cheung Pakchiu 《地震工程与工程振动(英文版)》2012,11(2):173-183
During past strong earthquakes, highway bridges have sustained severe damage or even collapse due to excessive displacements and/or very large lateral forces. For commonly used isolation bearings with a pure friction sliding surface, seismic forces may be reduced but displacements are often unconstrained. In this paper, an alternative seismic bearing system, called the cable-sliding friction bearing system, is developed by integrating seismic isolation devices with displacement restrainers consisting of cables attached to the upper and lower plates of the bearing. Restoring forces are provided to limit the displacements of the sliding component. Design parameters including the length and stiffness of the cables, friction coefficient, strength of the shear bolt in a fixed-type bearing, and movements under earthquake excitations are discussed. Laboratory testing of a prototype bearing subjected to vertical loads and quasi-static cyclic lateral loads, and corresponding numerical finite element simulation analysis, were carried out. It is shown that the numerical simulation shows good agreement with the experimental force-displacement hysteretic response, indicating the viability of the new bearing system. In addition, practical application of this bearing system to a multi-span bridge in China and its design advantages are discussed. 相似文献
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高墩梁桥的地震冲撞效应及其应对策略初探 总被引：1，自引：0，他引：1
国内外多次地震表明了高墩桥梁的地震冲撞破坏现象,针对目前国内大量兴建的高墩梁桥,有必要研究高墩梁桥地震冲撞效应和减轻桥梁地震冲撞破坏的应对策略。本文根据高烈度震区的1座高墩梁桥建立全桥的空间有限元模型,并在墩-梁结合部伸缩缝处采用非线性接触单元模拟相邻梁间的冲撞行为,同时考虑了下部支座的影响;考虑不同的强震动输入,采用非线性时程分析方法,研究了高墩梁桥的地震冲撞效应及减轻冲撞的有效措施。研究结果表明:本文采用的冲撞力学模型能够合理地模拟地震作用下结构的冲撞现象;冲撞行为对结构的地震反应影响复杂;地震动特性对冲撞效应影响显著;调整伸缩逢宽度或设置弹簧-阻尼限位装置可有效缓解结构间的冲撞效应。 相似文献
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Essential requirements from a base isolation system include wind restraint, stability and fail-safe capacity. A new base isolation system that satisfies all three requirements and possesses other advantages was tested on the earthquake simulator at the University of California under the base of a one-fourth scale nine storey steel structure. The base behaves as fixed for low magnitude inputs. When sliding starts the rubber bearings provide additional stiffness and recentering. Displacements are better controlled than the ones for a purely elastomeric isolation system. Vertical deflections due to large horizontal drift encountered in solely rubber systems are eliminated. The fail safe capacity is provided by tension restrainers installed inside the rubber bearings, and by the constant contact of the base with the sliders. Base shear hysteresis loops are drastically enlarged by the presence of the sliders. 相似文献