【作者】 刘迎春；

【导师】 薛素铎；

【作者基本信息】 北京工业大学 ， 土木工程， 2012， 博士

【摘要】 上承式拉索组合拱桥是在桁式组合拱桥的基础上发展和改进的新桥型，该桥型中采用柔性斜拉索代替桁式组合拱桥中刚性的预应力钢筋混凝土斜杆，该拉索成桥后作为永久性结构构件，施工过程中代替了临时扣索。本文以上承式拉索组合拱桥为研究对象，对上承式拉索组合拱桥的索力优化、施工过程、静力性能、动力特性和地震响应进行了系统研究，主要的研究工作和成果如下：1、介绍了该桥型的结构体系及特点，研究了索力变化对拱肋弯矩的影响以仙神河大桥的比较设计方案为工程背景，介绍了上承式拉索组合拱桥的结构体系，通过与其他上承式拱桥及索承网壳进行对比，得出该桥型的结构特点。其中最突出的特点是当主拱钢管拱肋合龙以后，仍可以通过调整斜拉索的索力来调整拱肋的内力，研究了索力变化对拱肋弯矩的影响。2、上承式拉索组合拱桥调索控制方法研究上承式拉索组合拱桥施工过程中，为了使拉索在各施工阶段达到最优索力，同一施工阶段需要对多根拉索进行索力调整，索力调整过程中必须考虑各拉索索力之间的相互影响。提出了批量调索时，拉索拔出量精确计算的施调索力法，推导了拉索拔出量及索力目标控制值的计算公式。批量调索时采用该方法计算各拉索的拔出量，在忽略拉索垂度情况下，不需要迭代计算，计算结果准确。以最大悬臂施工阶段为例，对比了上承式拉索组合拱桥调索的张拉控制方法。3、上承式拉索组合拱桥施工过程索力确定与受力性能研究上承式拉索组合拱桥采用悬臂桁架节段拼装的施工方法，在施工过程中通过调节索力大小控制拱肋的内力和线型，施工的核心问题就是确定各施工阶段拉索索力大小及拉索施调控制。把上承式拉索组合拱桥的施工过程分成30个施工阶段，对上承式拉索组合拱桥的悬臂节段拼装施工过程及拱肋混凝土的浇注过程进行了施工仿真分析，对施工过程的结构受力性能进行了深入研究。分别按“零弯矩法”和“零挠度法”计算了各施工阶段各拉索的最优索力，得出施工过程中索力的变化规律。4、上承式拉索组合拱桥成桥索力优化研究目前影响矩阵法和单位荷载法建立索力优化计算的数学模型时未考虑施调索力之间相互作用，针对这种不足，提出了成桥索力优化计算的双影响矩阵法，并进行了理论推导。分别以指定拱肋受力状态和拱肋弯曲应变能最小为索力优化目标，采用双影响矩阵法进行成桥索力优化计算，计算无迭代过程，可直接得到优化索力的精确值。分别采用了三种不同的方法对上承式拉索组合拱桥进行成桥索力优化计算。结果表明：双影响矩阵法具有计算速度快、计算精度高的优点。5、上承式拉索组合拱桥静力性能研究在成桥索力优化的基础上，研究了上承式拉索组合拱桥在恒载、车辆活载和温度变化作用下的受力性能。与普通上承式拱桥相比，上承式拉索组合拱桥经过索力优化以后，恒载作用下拱肋的受力状态得到明显改善。在相同等级的车辆活载作用下，上承式拉索组合拱桥的拱肋弯矩比普通上承式拱桥小得多，表明在普通上承式拱桥中增加拉索对减小车辆活载作用下的拱肋弯矩非常有效。在均匀温度变化作用下，上承式拉索组合拱桥的桥面纵梁受到两端地锚的约束不能自由伸缩，从而产生较大温度应力。6、上承式拉索组合拱桥的动力特性和地震响应研究采用子空间迭代法计算了上承式拉索组合拱桥的动力特性，采用振型分解反应谱法计算了上承式拉索组合拱桥的地震响应，并与结构参数相同的普通上承式拱桥的动力特性和地震响应进行对比。上承式拉索组合拱桥和普通上承式拱桥的基频相同，上承式拉索组合拱桥的第一阶竖向振动频率比普通上承式拱桥的第一阶竖向振动频率提高了将近一倍。表明在拱肋平面内增加拉索，对上承式拱桥横桥向的水平刚度没有影响，但使得上承式拱桥的竖向刚度得到明显提高。由竖向地震分量作用引起的某些地震效应比水平地震动分量引起的地震效应要大，抗震计算时竖向地震动响应不能忽略。更多还原

【Abstract】 The deck type arch bridge with diagonal cables is a new kind of bridge typewhich is the development and improvement of trussed combination arch bridge.Flexible diagonal stayed-cables are introduced into the deck type arch bridge withdiagonal cables, just as rigid prestressed concrete diagonals are adopted to trussedcombination arch bridge. Flexible diagonal stayed-cables act as both temporarysupporting cables during construction process, but permanent structural members ofthe completed status of the deck type arch bridge with diagonal cables. Taking thedeck type arch bridge with diagonal cables as the research object, this thesis studies itscable tensions optimization, construction process, static performance, dynamiccharacteristics and seismic responses systematically. The main research contents andachievements cover the following aspects:1、 Introduction of the structural system and features of this birdge type andresearch on impact of cable force variation on moment of arch ribsTaking the comparison design layout of Xianshenhe bridge as engineeringbackground, the structural system of the deck type arch bridge with diagonal cablesare introduced firstly. The structural features of the bridge type was obtained bycontrast with other deck type bridges and cable-supported lattice shells. The mostprominent feature of those is that the internal force may be adjusted by adjusting thecable force after closure of arch ribs. The impact of cable force variation on momentof arch ribs is studied.2、 Research on control method of cable tensions adjustment on the constructionprocess of the deck type arch bridge with diagonal cablesSeveral cable forces should be adjusted on the same construction stage in order tomake cable forces meet the optimal values during construction.“Adjusted cableforces method” is put forward to calculate pull-out length of every stayed-cable incase of batch adjustment of cable, taking into consideration the interaction betweenthe cable forces. The formula of pull-out length and adjusted value of cable forces isdeduced out in this thesis. Without iterative calculation，the exact pull-out length ofevery stayed-cable could be obtained by using this method immediately, on theassumption that sag effect of stayed-cable can be neglected. So the formula isconvenient to use. Taking the longest cantilever construction stage as example, thecomparison study of control method of cable tensions adjustment is carried out.3、 Research on determination of the cable forces and mechanical behaviorduring construction of the deck type arch bridge with diagonal cablesThe construction method of cantilevered segment assembling is adopted to build the deck type arch bridge with diagonal cables. Cable forces must be made adjustmentto control the internal force and lineshape of arch rib during construction, so the keycontruction technologies are determination of the cable forces and control of cabletensions adjustment. Construction process of the deck type arch bridge with diagonalcables is divided into thirty stages in this thesis. Construction simulation is carried outfor cantilevered segment assembling process of steel structure and pouring process ofarch rib concrete. The extensive studies have been conducted on mechanical behaviorduring construction of the deck type arch bridge with diagonal cables. Optimal cableforces are sought out by both “zero moment method” and “zero deflection method” atevery construction stage. Variation law of cable forces is gained on the constructionprocess.4、 Research on optimization of cable tensions of the finished deck type archbridge with diagonal cablesMathematical model is usually established for optimization of cable tension by“influence matrix method” or “unit load method” now, without regard to mutual effectbetween adjusted cable forces. Aimed at their shortcomings,“double influencematrixes method” for optimization of cable tensions is put forward and theoreticalderivation is made in this thesis. The optimization calculation of cable forces isperformed by means of two influence matrixes method, taking minimum bendingstrain energy and appointed stress states of arch ribs as optimum object separately.Without iterative calculation, exact cable forces could be obtained using this methodimmediately. Taking the deck type arch bridge with diagonal cables as an example,optimization calculation of cable tension is conducted using three different kinds ofmethod in this thesis separately. The research result shows that “double influencematrixes method” has the characteristic of fast operating speed and high precision.5、 Research on static performance of the deck type arch bridge with diagonalcables subjected to dead loadOn the base of optimization of cable tensions of finished deck type arch bridgeswith diagonal cables, its mechanical behavior is studied subjected to dead load,vehicle live load and uniform change in temperature。Since the cable forces actuallyare just optimal cable forces of the deck type arch bridge with diagonal cables, themechanical behavior of arch ribs of the deck type arch bridge with diagonal cables isbetter than ordinary deck type arch bridge. Applied the same grade of vehicle live load,bending moments in arch ribs of the deck type arch bridge with diagonal cables is lessthan the ordinary deck type arch bridge. The results show that it is effective to reducebending moment of arch rib subjected to vehicle live load that the stayed-cable isadopted to the ordinary deck type arch bridge When the deck type arch bridges withdiagonal cables is subjected to uniform change in temperature., the deformation of girder is restrained by ground anchors, so the girders have great temperature stresses.6、 Research on dynamic characteristics and seismic response of the deck typearch bridge with diagonal cablesThe natural vibration frequencies and modes of the bridge are calculated by thesubspace iteration method, and then its seismic response is also analyzed by means ofmode-shape decomposition response spectrum method. The comparative analysis ofdynamic performance and earthquake response is also carried out between the decktype arch bridge with diagonal cables and the ordinary deck type arch bridge with thesame structural parameters. This two kinds of deck type arch bridge have the samebasic frequency, whereas the first vertical vibration frequency of the deck type archbridge with diagonal cables is about twice as much as that of the ordinary deck typearch bridge. The results of the studies indicate that stayed cables have little influenceon horizontal stiffness of the deck type arch bridge with diagonal cables, but increasevertical rigidity obviously. Some seismic responses to vertical ground motioncomponent are greater than to horizontal ground motion component, so it is concludedthat vertical ground motion component play an important role in the composition ofseismic responses, and can not be ignored.更多还原