【作者】 刘文静；

【导师】 李黎；

【作者基本信息】 华中科技大学 ， 结构工程， 2010， 博士

【摘要】 地震是人类社会面临的最严重自然灾害之一,我国处于环太平洋和亚欧地震带之间,地震发生频率高、强度大、分布范围广、伤亡大、震灾严重。桥梁作为生命线工程,在抢险救灾和灾后重建中发挥关键性作用。隔震技术可以有效地减轻桥梁的地震灾害,但是由于取消了固定墩而全部采用隔震支座,其可靠性往往受到怀疑,国内缺少对这一领域的系统研究；另外,我国设计院目前采用的绝大部分桥梁设计软件都无法模拟隔震支座的非线性特性,所以急需对非线性隔震桥梁进行等效线性化以满足工程设计的需要。鉴于铅芯橡胶隔震支座(LRB)是应用最为广泛的隔震体系,本文以LRB隔震桥梁为研究对象,开展了以下几方面的研究工作：1、对LRB隔震桥梁的行车舒适度进行了评价。自编程序将行车荷载转化为动荷载,总结出移动荷载作用下桥梁响应的计算流程；通过分析LRB隔震支座的刚度对行车舒适度的影响,指出LRB隔震支座的各项参数中,只有竖向刚度与桥梁的行车舒适度有关；结合ISO规范、狄克曼指标与斯佩林指标,对不同结构形式的LRB隔震桥梁均得出行车舒适度良好的结论,同时指出其原因是LRB隔震支座的竖向刚度与非隔震桥梁使用的其它支座基本相同,其自身的固有特性决定了非常良好的行车舒适度。2、对LRB隔震桥梁在地震动作用下可能出现的碰撞响应进行了分析。在比较各种碰撞分析模型各自的特点与适用范围的基础上,选择了既能够较好反映碰撞物理事实又易于确定相关参数的Kelvin模型,解决了ANSYS平台中碰撞单元的模拟问题；通过对影响桥梁碰撞特性的各种参数进行深入分析,给出了避免LRB隔震桥梁在地震作用下发生碰撞的周期比范围建议,并确定了合理的碰撞单元刚度取值；通过分析LRB隔震支座水平刚度对隔震桥梁碰撞的影响,指出隔震支座水平刚度越小,桥梁发生碰撞的风险越大,碰撞响应也越大,不能片面追求隔震效果而一味地减小隔震支座的水平刚度,一定要进行地震作用下隔震桥梁的碰撞验算；通过对比隔震与不隔震桥梁的碰撞响应,指出发生碰撞时隔震桥梁可以对桥墩起到保护作用,为工程应用提出了指导。3、对LRB隔震桥梁进行了地震作用下的第一类和第二类动力稳定分析。根据Liapunov动力稳定性概念,解决了运用一次近似法判定多自由度复杂结构的第一类动力稳定性的问题；运用时程与特征值分析相结合的方法,自编程序,提出了第一类动力稳定分析的具体实现方法；基于纤维模型的非线性分析理论,针对LRB隔震桥梁提出了应用逐步增量动力分析法结合B-R判别准则对其进行第二类动力稳定分析；分析了不同结构形式LRB隔震桥梁的两类动力稳定问题,得出LRB隔震桥梁在地震作用下具有非常良好的动力稳定性的结论,并指出原因是隔震后墩顶位移大幅度减小,墩并没有进入塑性；为工程应用给出建议：墩较高、大震位移较大的连续梁桥,采用隔震技术后,动力稳定性能会有所减弱,需验算其动力稳定性。4、系统研究了LRB隔震桥梁的等效线性化方法。通过比较各种隔震支座等效线性化方法,提出了LRB隔震桥梁等效线性化的求解方法,给出了LRB隔震桥梁在地震作用下的反应谱分析计算步骤和LRB隔震桥梁在其他水平荷载作用下的验算标准,解决了计算LRB隔震桥梁地震响应时非线性问题与线性问题之间的矛盾,为工程技术人员进行LRB隔震桥梁的地震响应计算提供了一种简便有效的方法。更多还原

【Abstract】 Earthquake is one of the most serious natural disasters that human society faces, China is located between circum-Pacific seismic belt and Eurasian seismic belt, earthquakes are characterized by high frequency, intensity, wide distribution, large casualties and severe loss. Work as a lifeline, bridges play a key role in disaster relief and reconstruction. Isolation technology can reduce earthquake disaster of bridge effectively, but its reliability is often in doubt because of the cancellation of the fixed piers and the adoption of the isolation bearings, the domestic research seldom invlovs this field; in addition, currently most of the bridge design software used in China Design Institute can not simulate the nonlinear characteristics of isolation bearings, so equivalent linear for nonlinear isolated bridges is starved for meeting the design requirements. View of the lead rubber bearings (LRB) is the most widely used isolation system, LRB isolated bridge is selected as the research object in this dissertation and corresponding study includes the following aspects:1、The riding comfort of LRB isolated bridge was evaluated. The vehicle load was transformed into dynamic load by self-compiling program, the process for calculating the response of bridge under dynamic load was summarized; the result that only the vertical stiffness of LRB beared on the riding comfort among all of its factors was pointed out by analyzing the impact of the stiffness of LRB on the riding comfort; the riding comfort of different forms of LRB isolated bridges was analyzed with ISO standard, Diechmann indicator and Sperling indicator, the result showed that there riding comfort were well-drawn, which is determined by there own inherent characteristics, because the vertical stiffness of LRB and the bearings used in non-isolated bridges was basically the same.2、The possible pounding response of LRB isolated bridge subjected to seismic excitation was analyzed. Kelvin impact model was selected based on comparing characteristics and scope of application of various impact analytical models, because it could reasonably account for physical nature of pounding phenomena and relevant parameters were easy to determine, the problem that simulation of pounding element in ANSYS was solved; the suggestion of scope of period ratio for avoiding pounding of LRB isolated bridge subjected to seismic excitation was given, and reasonable value of the pounding stiffness was determined by deeply analyzed some factors which influenced pounding characteristics; the result that smaller horizontal stiffness of the bearing induced greater risk of pounding and pounding response for bridge was pointed out by analyzing the impact of the horizontal stiffness of LRB on pounding response, so the horizontal stiffness of the bearing can’t be reduced blindly to pursuit isolation effect, pounding of isolated bridge subjected to seismic must be checked; the result that isolated bridge played a protective role for the piers when earthquake happened was pointed out by comparing the pounding response between isolated and non-isolated bridges, guidance was proposed for project application.3、Two kinds of dynamical stability problems for LRB isolated bridge subjedted to seismic excitation were analyzed. The problem that use first approximation method to determine the first dynamical stability of multi-degree of freedom complex structure was solved based on Liapunov dynamic stability concept; a specific method for analyzing the first dynamical stability was proposed, the method of time-history combined with eigenvalue and self-compiling program were adopted; based on nonlinear theory of fiber model, the method that IDA combined with B-R criterion was proposed to analyse the second kind of dynamical stability problem of LRB solated bridge; two kinds of dynamical stability problems of different structure forms of LRB isolated-bridges were studied, the conclusion was that LRB isolated bridges had very good dynamical stability subjected to seismic excitation, the reason was that the displacements of pier tops were significantly reduced after isolation, the piers didn’t come to range of plastic; recommendations for engineering applications was given:for isolated bridges with higher piers and larger earthquake displacements, dynamic stability needs to be checked, because their dynamic stability might be weakened after use of isolation technology.4、The equivalent linear method of LRB isolated bridge was studied systematically. The equivalent linear method for LRB isolated bridge is proposed by comparing various equivalent linear methods for isolated bearing, analysis approach of spectrum subjected to seismic excitation and checking standard subjected to other horizontal loads for LRB isolated bridge were given, the contradiction between linear and nonlinear problems wh en calculating seismic response of isolated bridges was solved, a simple and effective method for calculating eismic response was provided to engineers and technicians.更多还原