【作者】 李勇；

【导师】 闫维明； 陈彦江；

【作者基本信息】 北京工业大学 ， 土木工程， 2012， 博士

【摘要】 高架桥是公路和城市交通的重要组成部分，其结构体系以连续梁和简支梁居多，但目前对于多点地震激励下高架连续梁桥动力响应的研究还较少，有关桥梁抗震规程和细则也未就地震动空间性对高架桥动力响应的影响给出明确规定。然而，在汶川等国内外强烈地震中，高架桥的破坏却较多，说明高架桥的抗震性能尚有待深入的研究和提高。同时，历史震害也为高架桥的抗震设计理念带来了一些新的启示。另一方面，近年来结构减隔震技术的不断发展，为新桥的抗震设计和旧桥的抗震加固均带来了新的理念和方法，且已有较多长大桥梁应用减震技术的工程实例。但是，关于采用减震技术提高高架桥抗震性能的研究及工程实例还很少。有鉴于此，本文将以双柱式桥墩直线连续梁桥这一高架桥常见的结构体系为主要研究对象，立足于国内外结构抗震减震研究领域前沿，对高架桥的多点地震响应规律和减震控制对策进行系统深入的理论与试验研究。主要的研究工作及成果包括如下几个方面：1.大质量法与绝对位移法的关系和计算精度及高架动力响应对地震动空间特性和结构参数的敏感性分析。分别基于绝对位移法、相对运动法和大质量法，推导了多点地震激励下结构运动方程，证明了大质量法和基底绝对位移法的结构运动方程是基本一致的；利用SAP2000软件，分析了基底附加质量和阻尼比对大质量法、阻尼比对基底绝对位移法计算精度的影响。数值模拟结果表明，对于大质量法，以高架桥墩底反力的104倍作为对应墩底的附加重量即可获得较高的计算精度，且阻尼比的影响较小，但是对于基底绝对位移法，阻尼比的变化则会对其精度产生一定的影响；利用ANSYS软件，分析了跨数、跨度、墩高等结构参数以及视波速、相干效应和局部场地效应等地震动相关参数对双柱式桥墩高架连续梁桥多点地震响应的影响，初步得出了几点定性结论。2.地震作用下高架桥的梁台碰撞响应与控制对策研究。基于ANSYS软件，完成了线性碰撞、Kelvin、Hertz和Hertz-Damp模型的二次开发；分析了梁台碰撞对双柱式桥墩高架连续梁桥地震响应的影响，结果表明，梁台碰撞可以防止活动支座位移失效、降低固定墩内力及变形，但增大了固定支座剪力；探讨了多点地震激励和近断层地震激励对高架桥梁台碰撞响应的影响，得出了多点地震激励和近断层地震激励将会增大碰撞力等结论；研究了具有两阶段出力特性复合式金属阻尼器及粘滞阻尼器作为防撞和减撞措施的适用性，结果表明，前者具有小震下耗能、大震下‘锁死’的功能，可有效地避免或降低多点地震激励和近断层地震激励下高架桥的碰撞响应，而后者近断层激励下高架桥的减撞效果则更佳。3.振动台台阵试验模型设计及其有限元模型修正。根据模拟地震振动台台阵的能力，以某双柱式桥墩高架连续梁桥为背景，设计、制作了几何相似比为1:10的缩尺模型；通过自由振动和振动台台阵白噪声激励试验，识别了试验模型的动力特性参数，并修正了其有限元模型，包括单向滑动支座的横向力学模型。有限元模型修正结果表明，将单向滑动支座的横向刚度视为刚性可能带来明显的计算误差，以双线性模拟为宜。4.一致与非一致地震激励下高架桥动力响应的试验研究。根据规范设计反应谱拟合了四类场地人工地震波，并选择了符合四类场地天然地震波，分别进行了水平一维和多维一致激励振动台台阵试验。结果表明，高架桥地震反应对于场地因素较为敏感，不同场地地震动激励下的响应相差较大；选取两条天然地震波和一条人工波，按照不同视波速进行了水平一维行波激励试验，并与一致输入下的试验结果进行了对比分析，研究了行波效应对高架桥地震响应的影响；分别生成考虑相干效应和局部场地效应的多点地震人工波，进行水平一维多点激励试验，分析了相干效应和局部场地效应对于高架桥地震反应的影响。5.粘滞阻尼器性能与减震效果的振动台台试验。设计并制作了四个粘滞阻尼器，测试了其在不同频率简谐激励下力-位移和力-速度关系曲线。测试结果显示，激励频率越高阻尼器出力与速度越接近线性关系；将粘滞阻尼器安装在高架桥模型的主梁与边墩之间，选取两条天然地震波和一条人工地震波分别进行了纵向一致输入、行波输入和多点输入下的振动台试验，考察了粘滞阻尼器对高架桥动力响应的减震效果。6.基于增量时程分析的一致与非一致地震激励下高架桥抗震性能研究。介绍了增量时程分析（IDA）的相关理论，对一致激励下典型高架桥的抗震性能进行了IDA分析，探讨了适用于高架桥抗震性能IDA分析的评价指标和强度指标。分析结果表明，与结构基本周期对应的、阻尼比为5%的加速度反应谱谱值Sa(T1,5%)和地震动峰值加速度PGA均可作为地震动强度指标，而桥墩塑性转角、支座位移及支座剪力均应该作为高架桥抗震性能IDA分析的评价指标。分析结果还表明，按现行盆式支座规程设计的桥梁支座横向抗剪承载力是偏低的，这可能是汶川地震中这类桥梁支座破坏的主要原因；对高架桥模型进行了水平单维逐步增大激励加速度峰值的振动台试验，并与有限元模拟结果进行了对比分析；考虑地震动的空间相关性，分别进行了行波激励、考虑相干效应的多点激励和考虑局部场地效应的多点激励下高架桥抗震性能的IDA分析，并与一致激励下的IDA分析结果进行了对比，初步的结论是，地震激励强度越大，高架桥一致激励响应与多点激励响应差别越大。更多还原

【Abstract】 Viaducts play an important role in modern highway transportation and citytransportation, and continuous girder bridges shares a high proportion, but the multi-point seismic response of them has been seldom taken into consideration. Some newaseismatic design principles of viaducts should be abtained according to the largequantity and various destructional forms of destroyed viaducts during Wenchuanearthquake, while the effect of seismic response under spatial earthquakes excitationsis not ruled in detail. On the other hand, the improved energy-dissipation technologyis more and more used in large-span bridges, while there is few study and applicationof the technology on the continuous viaducts. Therefore, this paper takes the two-column pier continuous girder bridge, the common type of viaducts, as the majorobject of study, and conducts some research in multi-point seismic response andenergy-dissipation theory. The main research and conclutions are as follows.1. The dynamic equations, separately based on the Base Absolute DisplacementMethod (BADM), relative motion method (RMM) and large mass method (LMM) arededuced. As a matter of fact, the ultimate equations of BADM and LMM are mainlythe same ones. The effects of additional base mass and damping ratio on the LMMprecision are discussed in use of SAP2000, and it is recommended that the additionalbase mass can be set the104times of base reaction force and the damping ratio affectsa little the LMM precision. Meanwhile, the damping ratio can affects a little on theBADM. The FE model of typical viaduct is established and the effects of the multi-point seismic response is analyzed considering some factors, including span, spannumber, pier height, travelling wave velocity, coherency and local site effect. Somequalitative conclusions are obtained.2. The calculation module of the pounding models in common, including linearmodel, Kelvin model, Hertz model and Hertz-damp model, are developed based onANSYS. The effects on the seismic response on of pounding is analyzed, and it isclearly can be deduced that the pounding can lead to the bearings’ damage andaggravate the plastic hinge damage near the bottom of pier. The seismic response ofviaduct under multi-point and near-fault earthquake excitations are calculated, whichconfirms that the multi-point and near-fault earthquake excitations can severelyenlarge the pounding force and response. A type of damper, Metal Alloy Brace (MAB),which possesses the characteristics of two stages of damping force, is recommendedto reduce even remove the pounding force and decrease the dynamic response of theviaduct. However, the seismic control of pounding response is more superior undernear-fault earthquake inputs.3. A1:10scaled bridge model of a typical viaduct designed and manufactured, andthe model bridge is placed on the shaking table array. The dynamic characteristic parameters are identified according to the artificial excitations and white noiseexcitations, and compared with the calculation value of FE model, which reveals thatthe parameters values match each other perfectly. Furthermore, it is verified that abilinear model should be used to simulate the traverse rigidity of the sliding bearings.4. The shaking table tests of the scaled viaduct are conduct under differentearthquake excitations. Four artificial earthquake records witch fitted the designedfour site types and four earthquake records which accord with the four site types areused to be as the one dimensional and two dimensional uniform excitations, whichreveal the impact on the viaduct’s seismic response of site factor. It is confirmed thatthere is a great deal of difference of the viaduct under different earthquake excitationsaccording to different sites. Besides two earthquake records and one artificialearthquake record are chosen to conduct the one dimensional travelling waveexcitations considering different travelling velocity, and the results are compared withthe seismic response under uniform excitations. At last, the artificial earthquakerecords which considering the incoherence effect and local site effect are generated toconduct the one dimensional shaking table tests to explore the seismic response ofviaducts under multi-point earthquake excitations.5. Four viscous dampers are designed and manufactured, and the damping force-displacement curves and damping force-velocity curves are gained under differentfrequency sine excitations. It is demonstrated that the relationship between thedamping force and velocity is closed to linear under high frequency sine excitation.Further, the Maxwell model is suitable to simulate the viscous dampers, while thetested hysterrisis curve is plumper than the calculated curve. Fit the dampers betweenthe side piers and the girder, and the damping effect of the viscous dampers is testedunder longitudinal uniform and multi-point excitations. The test dynamic responsecomparison of the viaduct between with dampers and without dampers shows that theviscous dampers play a part in energy dissipation.6. The Incremental Dynamic Analysis (IDA) theory is introduced and the IDAanalysis of the viaduct is conducted under uniform excitations. Meanwhile thedamage measure and intensity measure indexes are discussed during the analysis. It isrecommended that the plastic hinge rotation, the bearing displacement and the bearingshear force all should be taken as the DM indexes and the traverse bearings’ shearforce is not sufficient to resist the earthquake excitations. An artificial earthquakerecord is selected to conduct the IDA shaking table test and the tested results arecompared with the FE model analysis. The IDA is also conducted on the viaductunder the travelling wave excitations and multipoint excitations consideringcoherency and local site effect, and the results are also compared with the resultsunder uniform excitations. It is deduced that the distinction of the dynamic responseof the viaduct under multi-point dynamic response and uniform excitation of the viaduct changes along with the intensity of the earthquake excitations.更多还原