【作者】 梁炯；

【导师】 叶梅新；

【作者基本信息】 中南大学 ， 土木工程， 2012， 博士

【摘要】 本世纪以来,随着高速铁路建设的快速发展,我国已建和在建的特大跨度四线铁路钢桥有十来座。这些桥梁的结构形式多种多样。大部分采用了三主桁(拱)结构；当采用两主桁结构时一般都采取加设中吊杆或边吊杆等措施以减小桥面宽度。正在建造中的BJ桥是一座四线高速铁路专用斜拉桥,孔跨布置为(57.5+109.25+230+109.25+57.5)m。受建桥条件的限制,该桥只能采用两主桁结构,而且桥面上无空间加设中吊杆或边吊杆。斜拉桥总体上是一个柔性结构。两主桁四线高速铁路专用斜拉桥的特点是：结构柔、桥面宽、活载大。为确保高速列车运营的安全性和舒适性,必须对桥梁的整体刚度和桥面系的局部刚度给于足够的重视。本文以BJ桥为背景,采用数值分析和模型试验相结合的方法对两主桁四线高速铁路专用斜拉桥的桥面系结构形式及其对桥梁整体刚度的影响、桥面系局部刚度、桥面系结构的优化、桥面系模型试验的模拟方法、钢斜拉桥终张拉目标索力和张拉力的计算方法作了较为系统的研究。主要工作和创新性成果如下：1.针对两主桁四线铁路斜拉桥的特点,提出了两种桥面系结构方案：一种是“24m全宽整体桥面系结构方案(A1)”,另一种是“两主桁+边纵梁+水平K撑的减宽桥面系结构方案(A2)”。其中A2是一种创新性的桥面结构,国内外未曾有应用。2.研究了A1、A2两种桥面结构方案的特点及其对桥梁整体刚度的影响；提出了桥面系参与主桁共同作用程度的计算方法。结果表明,四线铁路斜拉桥整体桥面对桥梁整体刚度的影响较大。四线最不利活载作用下,A1和A2分别有58%和62%的桥面系(横截面积)参与了主桁共同作用。与无整体桥面的裸桁A0相比,主跨跨中的挠度分别减少了12%和14%,斜拉索的最大索力分别减小了9%和10%。3.对最不利活载作用下A1、A2两种正交异性板整体钢桥面系的局部变形作了较为系统的对比研究。提出了同一线两轨3m内相对变形量的物理意义及计算方法,提出和阐述了桥面变形的短波效应和横波效应、绝对位移和相对位移及相互间的转换方法。得出结论：与A1相比,A2节间中心桥面变形的相对位移约小了6.7%-12.6%,短波和横波的最大曲率分别小了49%和9.2%；外线和内线两轨3m内的相对变形量分别小了38%和48%。对BJ桥推荐了A2桥面系方案,并被采纳实施。4.提出了一种桥面系多变量、多目标的平行交叉优化方法(MOPOO法),推导了整套计算公式,给出了计算流程；用该法对A2桥面系基于局部刚度作了结构优化,给出了节间中心相对位移wc和外线两轨3m内的相对变形量△1,2的公共较优区域；在用钢量不变的情况下,该区域内wc和△1,2同时达到较优状态。5.对BJ桥A2桥面系,设计制作了一个三节间桥面系节段1：6的缩尺模型,提出了一种斜拉索对主桁下弦杆的轴压作用和对主桁节点竖向弹性支撑作用的模拟方法,完成了多种工况的模拟试验；考察了A2桥面系的变形、受力特性和水平K撑的作用。结果表明,A2桥面系由于设置了边纵梁,下弦杆的受力状态简单明了；边纵梁将大部分桥面荷载引向横梁跨边,使横梁几乎处于最佳受力状态,同时也改善了桥面变形和受力状态。模型试验证实了提出A2桥面结构方案的理念。6.研究提出了一种求解斜拉桥终张拉目标索力的“协调、平衡、优化”的计算方法和一种求解斜拉索终张拉力的“双结合”(有索、无索单元模型相结合、外力和索内力相结合)的增量形式的有限元模拟方法；给出了整套计算公式和计算流程。施工过程中只要按此法算出的张拉力和相应的张拉顺序经一轮次张拉就可达到目标索力,既减少了施工工作量又确保施工过程中桥梁结构受力的安全性。本文的研究成果为BJ桥的设计、施工提供了依据,也为其他桥梁的相关研究、设计和施工提供了参考。更多还原

【Abstract】 Since the beginning of21th century more than10extra large span four-line high-speed railway steel bridges have been completed or under construction in China with the rapid developing of the construction of high-speed railway. The structure types of these bridges are diverse. Most of these bridges have three main trusses or arches. When only two main trusses are used, middle suspenders or side suspenders are often arranged to decrease the width of the deck system. BJ Bridge which is under construction now is a Four-lines High-speed railway Cable-stayed Bridge (FHCB) with the spans arranged as (57.5+109.25+230+109.25+57.5)m. Restricted by the construction conditions on site, only two main trusses can be arranged, and no space available on the deck to arrange middle suspenders or side suspenders. Cable-stayed bridges are flexible structures. The characteristics of FHCB with two main trusses are flexible, wide deck and large live load. To guarantee the safety and comfort of the service of high-speed trains, the stiffness of the whole bridge and the deck system is the key problem and should be pay more attention.Take BJ Bridge as background, the following problems are studied: the structure type of the deck system and their influence to the stiffness of the whole bridge, the stiffness and optimization of the deck system, the simulation method of the model test of deck system, and the calculation method of the final cable forces and the tension cable forces of the final tensioning. Main research work and innovative achievements are listed below.1. Aimed at the characteristics of FHCB, two deck system plans are presented. One is24m total wide monolithic deck system (A1), another is wide reduced monolithic deck system with side stringers and horizontal K-shaped braces (A2). A2is a innovative deck system type and has not applied before.2. The features of A1, A2and their influence to the stiffness of the whole bridge are studied. A calculation method of the level of deck system working together with the main trusses is proposed. The results show that the influence of the monolithic deck system to the stiffness of the whole FHCB is considerable. Under the action of the four-line worst-case live load,58%and62%of the cross section area of A1and A2work together with main trusses respectively,12%and14%of the deflection of midspan are cut down from that of the bare main truss structures (Ao) respectively,9%and10%of the maximum cable forces are decreased respectively.3. The local deformations of A1and A2deck systems under the worst-case live load are studied and compared. The physical significance and calculation method of the relative deformation of two trucks of one line are presented. The short wave and transversal wave of deformation of deck system, the absolute and relative displacements, and the transfer approach between them are also presented and expounded. The following conclusions are obtained. Compared with A1, the relative displacement of the deck system at the center of one panel of A2are decreased about6.7%to12.6%, the maximum curvature of the short wave and transversal wave of A2are decreased49%and9.2%respectively, and the relative deformation between the two trucks of the outer line and inner line within three meters of A2are decreased38%and48%respectively. A2is recommended to BJ Bridge and adopted.4. A Multi-variable multi-Objective Parallel Overlay Optimization method (MOPOO) is proposed. The computational formulas are developed and the calculating flow is presented. Using this method, the structure of A2is optimized based on the local stiffness of the deck system. The overlay better area of the relative displacement wc at the center of one panel and the relative deformation Δ1,2of the two trucks of outer line within three meters are obtained. In this area wc and Δ,2are all under better state while the steel consumption remains the same.5. Simulating A2deck system of BJ Bridge, a three panels segment model of deck system with the reduced scale1:6is designed and manufactured. The simulation methods of the axial load of lower chords and the elastic supports of the joints of main trusses from the cables are proposed. The tests of about ten load cases are completed. The deformations, stress states and the effect of horizontal K-shaped braces are investigated. The results show that the stress state of the lower chord is simple and clear because of the arrangeem.at of the side stringers. Most of the loads are transferred to the side area of the crossbeams by the side stringers, thus the crossbeams are under the best state, and the deformation and stress state of the deck system are also improved. The model tests verify the idea of proposal of A2.6. A conforming, equilibratory and optimized calculation method to calculate the final cable forces in the final tensioning is proposed. A double-combine incremental finite element simulation method to calculate the tension cable forces in the final tensioning is also proposed. The double-combine means the combination of finite element model with and without cable elements, and the combination of external forces and cable forces. The computational formulas and calculating flow are presented. In the construction the final cable forces can be obtained by only one round tension process using the final tension forces and tension sequence which calculated by this method, and the tension work is reduced and the safety of the bridge during tensioning can be guaranteed.The research results have already been used in the design and construction of BJ Bridge, and provide references to the study, design and construction of other bridges.更多还原