【作者】 李忠军；

【导师】 李惠； 郭安薪；

【作者基本信息】 哈尔滨工业大学 ， 防灾减灾工程及防护工程， 2010， 博士

【摘要】 强烈地震作用下,高架桥梁相邻桥跨之间由于存在动力特性的差异,或者受到非一致地震动作用的影响,容易遭受碰撞破坏。强烈地震作用下高架桥梁碰撞过程中存在复杂的材料非线性、几何非线性和接触非线性,碰撞机理复杂。此外,针对地震所引发的高架桥梁碰撞,如何采用工程措施降低结构的震害,是需要迫切解决的问题。本文针对高架桥梁在强烈地震作用下的碰撞机理及控制措施,采用显式非线性有限元分析技术和简化分析方法相结合的方法,研究了地震碰撞破坏机理和控制方法,主要内容包括:(1)通过显式非线性有限元分析软件LS-DYNA,针对某三跨简支悬臂梁桥的精细化建模,研究了地震动幅值、主梁周期、伸缩缝间距和支座阻尼比等结构参数变化对结构碰撞动力特性的影响及结构的碰撞机理。(2)针对在高架桥梁伸缩缝处安装橡胶缓冲材料,以减轻强震作用下高架桥梁碰撞的工程技术措施,通过显式非线性有限元精细化建模和分析,研究了橡胶缓冲材料的剪切模量、厚度和摩擦系数等参数对减轻结构碰撞动力响应的影响。探讨了采用橡胶缓冲材料减轻高架桥梁地震碰撞的可行性以及材料参数选择的方法。(3)通过理论与试验相结合的技术手段,研究了采用MR阻尼器对高架桥梁在强烈地震作用下碰撞动力响应的半主动控制方法。分析过程中以Kelvin和Hertz阻尼模型模拟结构间的碰撞,基于LQG控制算法提出了高架桥梁碰撞的半主动控制策略,并进行了试验验证。此外,基于高架桥梁模型振动台碰撞试验结果,建立了一套识别了Kelvin和Hertz阻尼模型的方法。分析结果表明,目前以结构轴向刚度作为Kelvin模型碰撞刚度的取值方法,与试验所识别的结果存在较大差异,如何对碰撞简化分析模型参数进行合理取值,是值得进一步深入研究的课题。(4)针对双向地震作用下,高架桥梁由于微小质量偏心所引起的非轴向点面碰撞,提出了高架桥梁二维点接触碰撞的摩擦接触模型,并建立了相应的力学分析模型。通过双向地震动输入下的高架桥梁振动台模型试验,验证了摩擦接触模型以及所建立的结构力学分析模型用来模拟结构扭转碰撞的正确性。试验结果也表明,高架桥梁的微小扭转容易导致结构的点面扭转碰撞,在结构抗震设计中应予以重视。更多还原

【Abstract】 Highway bridge is sensitive to pounding damage due to either the difference of dynamic characteristics between the neighboring segments or the effects of asynchronous earthquake when subjected to strong earthquake excitations. During the structural pounding, highway bridge behaves complex inherent characteristics of material nonlinear, geometric nonlinear and contact nonlinear, which make the impact mechanism very complex. Furthermore, aiming at the seismic-induced pounding of highway bridges, how to prevent the structural pounding using suitable engineering technique is an important issue that should be solved.This dissertation investigates the pounding mechanism and the pounding reduction technique by using the explicit nonlinear finite element approach and the simplified impact model approach. The main contents include:(1) Based on the refining finite element model of a three-span highway bridge, it investigates the pounding mechanism and the effects of the earthquake amplitude, natural frequency of the main span, expansion joint separation and the damping ratio of the base-isolation system on the dynamic responses of the structures.(2) By using rubber cushion material, it investigated the possibility of using the rubber cushion material for the pounding reduction of the highway bridges. The effects of the shear modulus, thickness and the friction coefficient of the material for the performance of the pounding reduction is also investigated by using the explicit nonlinear finite element approach for establishing the parametric selection principle of the rubber cushion material for the pounding reduction of highway bridge.(3) With the theoretical and experimental techniques, the possibility of using MR dampers for preventing the pounding damage of highway bridges is investigated with semi-active control method. During the analysis, it uses the Kelvin and Hertz damp impact model for modeling the structural pounding and develops the semi-active control strategy based on the LQG control algorithm through experiment validation. The analytical results indicate that there are significant difference between the theoretical impact stiffness with structural axial stiffness and the identified impact stiffness. How to determine the parameters of the impact model is an important issue that should be investigated in future. (4) Considering the torsion-induced pounding of highway bridge due to mass eccentricity, it investigates the point-to-surface impact and proposes the corresponding friction-contact impact model for highway bridge with bi-directional earthquake excitations. The analytical model of the highway bridge with point-to-surface pounding is also established. Through the shaking table test with bi-directional earthquake inputs, it validates the accuracy of the proposed friction-contact impact model and the analytical model of the structure with point-to-surface pounding. The experimental results indicate that the torsion-induced pounding of the highway bridges should be paid more attention during the seismic design.更多还原