【作者】 王福春；

【导师】 梁力；

【作者基本信息】 东北大学 ， 工程力学， 2011， 博士

【摘要】 预应力混凝土折线塔斜拉桥是一种新型的斜拉桥结构,其结构新颖,造型独特,具有良好的景观效果。沈阳市富民桥是世界上第一座也是至今为止唯一一座预应力混凝土折线塔单索而斜拉桥,其与直塔斜拉桥和斜塔斜拉桥相比,结构的受力和施工方法发生了很大的变化。本文以该桥为工程背景,对桥梁特殊结构的力学特点进行了理论分析,并利用现代有限元数值方法和模型试验方法,对混凝土折线塔斜拉桥的主要力学特性进行了分析研究。斜拉桥的主塔主要承受斜拉索传递的巨大轴力,同时承受一定不平衡荷载下的弯矩。但对于折线塔斜拉桥来说,由于主塔存在折角,在主塔轴线发生变化的折角处巨大的轴向力传递方向发生了变化,因此折角处将产生一较大水平向拉力,导致折线塔塔壁产生面外弯曲,因此国外已建折线塔斜拉桥均采用钢塔来解决折角处的应力集中等问题。本文从分析混凝土折线塔的受力特点出发,通过有限元数值分析和模型试验研究,对混凝土折线塔锚固区、主塔折角等关键部位的力学特性进行了分析研究。对国内外常见斜拉桥合理成桥索力和合理施工索力的优化方法进行了分析研究,比较了各种优化方法的优缺点。根据折线塔斜拉桥的静力平衡特征,给出预应力混凝土折线塔斜拉桥主要构件尺寸的设计方法,进一步采用最小弯曲能量法并结合假载法及内力平衡法来确定混凝土折线塔斜拉桥合理成桥索力。充分考虑到混凝土折线塔施工阶段的受力特点,确定主塔的浇筑顺序,采用最小二乘法对全桥进行正装迭代计算确定拉索初张力。分别采用反应谱法和时程分析法,对同等跨径下的预应力混凝土直塔斜拉桥和预应力混凝土折线塔斜拉桥在支承体系和不对称体系下的抗震性能进行了分析研究。分析结果表明预应力混凝土直塔斜拉桥和预应力混凝土折线塔斜拉桥动力特性基本吻合,主塔造型的改变对斜拉桥的动力特性的影响比较小。不对称体系频率计算值普遍高于支承体系,不对称体系斜拉桥整体刚度大于支承体系,两种体系在地震荷载作用下,塔顶位移和梁端位移相差不大,因此,采用不对称体系可以省去其中一个主塔下造价昂贵的大吨位支座,并且有利于桥梁的日后维修养护工作依据相似理论,结合沈阳市富民桥特点,对全桥施工阶段受力情况进行全过程模拟试验及成桥后荷载试验。实测了施工过程和成桥后在各种荷载作用下主梁及主塔控制截面应力和斜拉索索力。试验结果表明本文提出的预应力混凝土折线塔斜拉桥索力确定方法确定的成桥索力和初张力,能保证折线塔主梁、主塔各控制截面应力均能满足规范要求,且实测索力与理论计算索力吻合较好,可保证桥梁正常运行。更多还原

【Abstract】 The prestressed concrete cable-stayed bridge with fold-line tower is a new structure, for its novel structure and unique shape, it has a good landscape. Fumin Bridge, which Located in Shenyang, is the first and the only prestressed concrete cable-stayed bridge with fold-line tower and a single cable plane in the world. Compared with straight tower and inclined tower cable-stayed bridge, its structure and basic mechanical property changes a lot. Based on the finite element theory and the model test, the behaviors and mechanisms of Fumin Bridge were analyzed.The main tower of the cable-stayed bridge subjected to axial force and bending moment transmitted from the cable. Because of the axial loading transmit direction changed at the fold area, a large amount of tension force generated, and the tower wall bended out-of-plane. Due to the request of the structure, cable-stayed bridge with fold-line tower which has been built abroad all used steel tower to solve the stress concentration at the fold area. Based on the finite element analysis and experimental study, the mechanic properties of the key parts on concrete fold-line tower such as cable, tower anchorage area were analyzed.Optimization method of reasonable cable force in the finished and construction cable-stayed bridge was analyzed, and the advantages and disadvantages of each method were obtained. According to the static balance features of the fold-line tower cable-stayed bridge, the design method of the main component of prestressed concrete cable bridge with fold-line tower was introduced. Moreover, the least bending energy method and stress balance method were adopted to determine the reasonable cable force in the finished cable-stayed bridge. Considering the mechanic property of the concrete fold-line tower under construction stage, pouring order of the tower was determined. Least square method and iterative calculation was adopted to determine the initial cable force.Based on the response spectrum and time history method, the seismic performance of prestressed concrete cable-stayed bridge with straight-line tower and fold-line tower under supporting system and asymmetric system were analyzed. The results showed that the dynamic characteristics of prestressed concrete cable-stayed bridge with straight-line tower and fold-line tower basically agreements. The changes of tower shape have little influence to the dynamic characteristics of cable-stayed bridge. The calculated results show that frequency number and integral rigidity of asymmetric system were larger than supporting system. The differences between tower-top displacement and beam-end displacement of the two systems under seismic load were little. So, a costly large-tonnage bearing could be saved when the asymmetric system was adopted, which also gave advantage to the future maintenance of the bridge.Model tests on the full bridge under construction process and finished stage were carried out, and the controlling section stress and the cable force under various loads of main beam were obtained. The experiment results showed the method to determine the finished and initial cable force could assure the controlling section stress of prestressed concrete cable-stayed bridge, and the measured cable force and theoretical value were good agreements with the codes.更多还原