郑州黄河钢管混凝土拱桥力学性能分析

【作者】 孙征；

【导师】 陈淮；

【作者基本信息】 郑州大学 ， 结构工程， 2004， 硕士

【摘要】 拱桥是一种极具美学价值的桥梁形式，也是桥梁的基本桥型之一，在我国又有深厚的历史渊源，在工程中得到了广泛应用，是我国建设较多的桥型。由于钢管混凝土在桥梁上的应用，同时解决了拱桥高强度材料应用和施工两大难题，使拱桥更加轻巧，表现力也更强，给拱桥的发展注入了新的活力。因此，钢管混凝土拱桥在我国得到迅速发展，我国建造了大量的拱桥。中、下承式拱桥建筑造型极佳，在城市桥梁中往往受到青睐而成为城市的标志性建筑，目前仍在向更大跨径、更大规模的方向发展，应用区域和范围也在不断扩大。当前，由于缺乏专用的设计规范和施工技术规范，钢管混凝土拱桥的设计、施工只能依据建筑行业的钢管混凝土规程并结合桥梁设计规范的有关条文进行，这对该种桥梁实际应用带来了一定的困难。 近年来，由于主客观原因导致了一些拱桥发生坍塌事故，造成了严重的人员伤亡和经济损失，从这些事故分析可以得出这样的结论：中、下承式拱桥的断桥与垮塌事故大多与吊杆的健康状态有关，若能对拱桥吊杆的健康状态进行经常及时地或实时在线地监测与诊断，多数拱桥的重大事故是可以避免的。要对中、下承式拱桥的吊杆健康状态做出正确判断，需要采用精细的有限元模型对桥梁整桥进行力学性能分析，了解桥梁的受力特性。尤其是作为桥梁重要受力构件的吊杆，在传统设计中是利用桥面简支梁模型计算其内力，忽略了桥面连续及弹性支撑对吊杆内力的影响，计算结果粗糙。因此只有采用以拱肋、吊杆和桥面体系为一体的整体精细有限元计算模型，才能准确求解其内力，为系杆拱桥的设计提供依据，同时也为吊杆的健康检测与诊断提供详实的力学资料。开展拱桥力学性能分析具有重要的理论意义和实用价值，本课题正是在此背景下开展的。 本文根据京珠国道郑州黄河特大桥主桥——下承式钢管混凝土拱桥的结构特点，采用有限元法对该桥进行有限元离散，用空间梁单元模拟系杆梁、端横梁、中横梁、纵梁和拱肋等构件，用只承受拉力的空间杆单元模拟吊杆，建立了桥梁空间力学计算的有限元模型，利用ANSYS程序对该桥进行了空间力学计算，得到了该桥梁在不同工况下的力学性能，探讨了吊杆损伤对该拱桥静态力学性能、动态特性、稳定性的影响，取得的主要成果如下： (1)通过对该桥在恒载和外侧汽车荷载偏载作用下的静力计算和分析，可以看出，在桥梁完好状态下： ①吊杆受力：吊杆张力关于跨中对称，端部2根吊杆张力相对较小(最端部吊杆张力最小)，其余中部位置吊杆张力较大，且各根吊杆所受的张力分布比较均匀，吊杆张力相差不大(最中间部位吊杆张力最大)；活载增大了吊杆所受的张力，增大比较均匀，外侧吊杆所受的张力增加幅度比内侧大。 ②拱肋和系杆梁受力：拱肋和系杆梁受力关于跨中对称，拱肋各个截面全截面受压，吊杆位置处拱肋的弯矩发生变化和剪力产生突变；系杆梁全截面受拉，系杆梁由于端横梁的约束，其弯矩图与两端固定梁弯矩图相似，吊杆位置处系杆梁弯矩图发生变化和剪力产生突变；活郑州大学硕士学位论文载增大了拱肋和系杆梁受力，外侧和内侧拱肋轴力增大变化大致均匀，拱肋弯矩变化不均匀，大致关于跨中对称，在1/4位置处增大最大;拱肋剪力变化较均匀;外侧和内侧系杆梁轴力变化较均匀，系杆梁弯矩变化不均匀，在右1/8位置处增大最大。 ③拱桥整体变形:全桥变形以桥面的竖向位移为主，其它构件空间变形较小;活载增大了该拱桥整体变形，竖向位移增大变化大致均匀。 (2)吊杆损伤对拱桥构件受力的影响: ①吊杆受力分析:由于去除了某些损伤吊杆，引起其它吊杆张力增大，特别是与之相邻的吊杆张力增大最多，吊杆张力增大大致在损伤位置处向两边逐渐递减，外侧吊杆张力变化比内侧吊杆张力变化大。 ②拱肋受力分析:拱肋轴力变化比较小，也比较均匀;拱肋弯矩变化不均匀，在去除损伤吊杆位置处弯矩增加最大，特别是与之相邻的拱肋弯矩增大较多，其它位置弯矩有所增加;拱肋剪力在去除损伤吊杆位置处有突变，增加较多(应考虑剪力的符号)，其它各关键点剪力变化较小，并且去除损伤吊杆位置处左、右变化趋势相反。 ③系杆梁受力分析:系杆梁轴力增大变化较均匀，一般变化量较小，基本上都是从一侧向另一侧逐渐变化的;系杆梁弯矩变化不均匀，在去除损伤吊杆位置处弯矩增加最大，其它位置弯矩增大较少;系杆梁剪力在去除损伤吊杆位置处有突变，去除损伤吊杆位置处两侧剪力增加较多，其它位置剪力增加较小。 ④拱桥变形分析:在去除损伤吊杆位置处，拱肋位移减小，其它各关键点位移增大，在有损伤吊杆所在侧拱肋位移变化较大，另一侧拱肋位移变化小;系杆梁位移增加，特别是损伤吊杆位置处系杆梁位移增加最大。 总的来讲，吊杆损伤对吊杆系静张力的分配有较大的影响，一旦某根吊杆退出工作，与之相临的吊杆所受的静张力也会随之大幅度增加;吊杆损伤对拱肋和系杆梁的轴力影响较小，但对弯矩有较大影响;损伤处的竖向位移也较大。 (3)该拱桥的振动主要有钢管混凝土拱肋的面外振动、桥梁整体的竖向振动和扭转振动3种振动形式。拱肋的面外刚度相对较小，桥梁第1阶振动表现为拱肋的面外横向振动;桥面系不存在低阶的振动形式，其竖更多还原

【Abstract】 Arch bridge, with extremely high aesthetic value, acting as one of the fundamental bridge types and possessing a profound historical origin, is widely applied in engineering and is a popular bridge type in our nation’s construction. As the application of CFST (Concrete Filled Steel Tube) structures to bridges has solved the problem of the application of high-strength material of arch bridge and the problem of the construction of arch bridge, two main bridge puzzles, arch bridge becomes much lighter and has stronger expressive force and the development of arch bridge is infused with fresh vitality. Therefore, CFST arch bridge has gained a booming opportunity in our country and meanwhile a large number of arch bridges have been constructed in our country. With wonderful architectural styles, through and half through arch bridges, are commonly favored in urban bridge design and construction so as to be the symbol of civic constructions. For the moment, they are still advancing on wider span and larger scale and their application region and scope are enlarged continually. Currently,.the design and construction of CFST arch bridge can only be based on the CFST specifications in the construction industry with the combination of relevant clauses in the bridge design codes which bring about certain difficulties to the practical application of this sort of bridge for the lack of special design codes and construction codes.In recent years, some subjective and objective reasons resulted in some accidents of arch bridge collapses and severe casualties and economic loss related. Such conclusion can be derived from these accidents’ analyses that breaking up and collapse of through and half through bridges mostly relate with the health condition of suspenders; if timely and real time online monitoring and diagnoses are conducted, a majority of serious accidents can be avoided. Only by adopting refined FEM (Finite Element Method) to analyze the whole bridge’s mechanical properties to get the stress and strain characteristics of the bridge, can the suspenders’ health conditions of the through and half through arch bridges be exactly estimated. Especially the suspenders, as one of the vital load-bearing members of the arch bridge, whose internal forces are calculated by making the model of deck simple-supported beam and ignoring the effects that are brought on to the suspenders’ internal forces by the factors such as deck’s continuity and elastic supports, are coarsely calculated during the traditional design. Consequently, only by adopting the whole and fine finite element calculating model which is integrated by arch ribs, suspenders and the bridge deck system, can its internal forces be precisely calculated to provide references to the tied arch bridge’s design and detailed mechanical materials to the health detection and diagnoses of suspenders. Conducting the analyses of arch bridges’ mechanical properties takes on its important theoretical senses and practical values, and this dissertation is written and developed in this background.In this dissertation, the Yellow River main bridge in Zhengzhou section of Jingzhu freeway, a through CFST arch bridge is discretized by the FEM according to its structural characteristics with the spatial beam element simulating the horizontal tied beams, end floor beams, middle floor beams, arch ribs and the like and with the spatial link element simulating the suspenders to erect the bridge’s spatial mechanical computational finite element model. Finite element common software ANSYS is applied for its spatial mechanical calculation and mechanical properties in various cases are obtained. Meanwhile, influences that the damage of the suspenders has brought on to this arch bridge’s mechanical properties of the static state, dynamic characteristics and stability are discussedso as to acquire the main fruit in the dissertation below:(1) From the static calculation and analyses of the bridge under the dead load and the deflected live load of the outboard automobile load, it is obvious that更多还原