下承式钢管混凝土拱桥吊杆破损对结构体系安全性研究

发布时间：2018-04-17 16:15

本文选题：吊杆索力测试 + 吊杆破损　；参考：《兰州交通大学》2014年硕士论文

【摘要】：由于吊杆受力状态复杂，又受到锈蚀、疲劳等因素的影响使其发生破损，吊杆破损会引起吊杆系内力重分布，所以在拱桥设计中针对吊杆增加破损安全计算是很有必要的。这样不仅可以明确地计算出吊杆破损对其它吊杆系、拱肋及系梁受力状态的影响以及吊杆破损对拱桥稳定性的影响，而且对提高拱桥整体的安全性具有很重要的意义。为了探讨下承式钢管混凝土拱桥吊杆破损对结构体系是否是破损安全的，本文以南水北调中线工程河南叶县1标段魏岗铺北跨渠下承式钢管混凝土系杆拱桥为工程背景，首先，采用振动频率法分析了吊杆两端在不同边界条件下，其理论计算索力与现场标定K值后的实测索力之间的差异。通过计算分析得到：采用等效铰接法计算得到的吊杆索力与现场标定K值后实测索力比较接近，误差均在5.5%以内，满足工程要求。其次，采用有限元软件MIDAS/CIVIL分析计算了该下承式钢管混凝土拱桥在不同吊杆破损工况下的力学性能和空间稳定性。静力安全性方面，当单根吊杆破损时，剩余吊杆最大应力、应力幅以及桥梁结构受力均满足设计和规范要求，单根吊杆破损对该下承式钢管混凝土系杆拱桥静力响应影响较小，单根吊杆破损是破损安全的；当有连续的3对吊杆发生破损时，这会导致桥梁结构某些位置出现拉应力、位移变化过大等而导致局部混凝土开裂，更严重的是引起吊杆的连锁破损，，从而引起桥梁结构严重损伤，甚至整体垮塌。动力安全性方面，该下承式钢管混凝土拱桥的振动形式主要表现为拱肋的面外横向振动、拱桥整体的竖向振动和扭转振动。拱肋的面外刚度相对较小，面内振型出现晚于面外振型。吊杆的设置使得桥面竖向振动表现为该拱桥的整体竖向振动；吊杆破损对该拱桥拱横向振动的自振频率影响较小，而对全桥竖向和扭转振动影响较大。吊杆的破损将导致桥梁结构竖向和扭转振动自振频率的降低，可见吊杆的完好对拱桥整体的安全性至关重要。稳定安全性方面，各工况对应的桥梁结构第一阶稳定系数在4.85～5.26之间，满足根据国内已建钢管混凝土拱桥的设计经验，认为施工和运营期稳定系数大于或等于4的要求；吊杆破损对该拱桥的低阶稳定安全系数影响较小，即吊杆破损对结构体系的影响是破损安全的。其失稳形式主要表现为拱肋横向面外失稳。
[Abstract]:It is necessary to increase the damage safety calculation in the design of arch bridge because of the complex stress state of the suspender and the influence of corrosion and fatigue. The damage of the suspender will lead to the redistribution of the internal force of the suspender system, so it is necessary to increase the damage of the suspender in the design of the arch bridge.In this way, not only can the influence of suspender damage on other suspenders, arch ribs and girders and the stability of arch bridges be clearly calculated, but also it is of great significance to improve the overall safety of arch bridges.In order to study whether the through concrete filled steel tube arch bridge is damaged and safe to the structure system, this paper takes Weigang Pu Bei span canal through tie arch bridge of Weigang Pu North span canal of Henan Province as the engineering background, first of all, the paper takes the middle line project of South-to-North Water transfer Project as the engineering background.The difference between the theoretical calculation of cable force at the two ends of the suspension rod under different boundary conditions and the measured cable force after calibration of K value in the field is analyzed by means of vibration frequency method.Through calculation and analysis, it is concluded that the cable force calculated by the equivalent hinge method is close to the measured cable force after calibration K, and the error is less than 5.5%, which meets the engineering requirements.Secondly, the finite element software MIDAS/CIVIL is used to analyze and calculate the mechanical properties and spatial stability of the through concrete filled steel tube arch bridge under different suspender failure conditions.In the aspect of static safety, when a single suspender is damaged, the maximum stress, the amplitude of stress and the stress of the bridge structure all meet the design and specification requirements, and the failure of the single suspender has little effect on the static response of the through concrete-filled steel tubular tied arch bridge.The breakage of a single suspender is safe, and when there are 3 pairs of suspenders damaged, this will lead to tensile stress in some parts of the bridge structure and excessive variation of displacement, which will lead to local concrete cracking.What is more serious is the chain damage of suspenders, which can cause serious damage of bridge structure and even collapse of the whole bridge.In terms of dynamic safety, the vibration form of the through concrete filled steel tube arch bridge is mainly the lateral vibration of the arch rib, the vertical vibration and the torsional vibration of the whole arch bridge.The out-of-plane stiffness of arch rib is relatively small, and the in-plane mode appears later than the out-of-plane mode.The vertical vibration of the bridge deck is the whole vertical vibration of the arch bridge, and the damage of the suspension rod has little effect on the natural frequency of the transverse vibration of the arch bridge, but has a great effect on the vertical and torsional vibration of the whole bridge.The damage of suspension rod will lead to the reduction of natural vibration frequency of vertical and torsional vibration of bridge structure. It can be seen that the integrity of suspension rod is very important to the safety of the arch bridge as a whole.In terms of stability safety, the first-order stability coefficient of bridge structure corresponding to each working condition is between 4.85 and 5.26, which meets the requirement that the stability factor of construction and operation period is greater than or equal to 4 according to the design experience of the steel tube concrete arch bridge built in China.The damage of suspenders has little effect on the low order safety factor of the arch bridge, that is, the damage of the suspenders is safe to the structural system.The main form of instability is lateral instability of arch rib.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U441;U448.22

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