大跨度桥梁设计在公路桥梁中的应用.doc

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1、【精品文档】如有侵权，请联系网站删除，仅供学习与交流大跨度桥梁设计在公路桥梁中的应用.精品文档.大跨度桥梁设计在公路桥梁中的应用摘要：大跨度公路桥梁往往处于公路交通运输的枢纽和咽喉地段，为道路生命线工程的重要组成部分。文章对大跨度桥梁的桥梁体系选择、上部结构的设计和下部结构的设计进行了探讨关键词：大跨度桥梁 公路桥梁 桥梁设计前言大跨度公路桥梁往往处于公路交通运输的枢纽和咽喉地段，为道路生命线工程的重要组成部分。在桥型的比选上有相当的难度和复杂性，而桥梁的设置是否合理，桥梁设计方案是否合理，直接影响整条路线的工程造价及使用功能。因此在设计中必须协调好桥梁各细部构造与地形、地质之间的关系。1 大

2、跨度桥梁结构及其设计理论的发展随着我国经济的发展,大跨径桥梁的建设在20世纪末进入了一个高潮。大跨度桥梁形式多样,有斜拉桥、悬索桥、拱桥、悬臂桁架桥及其它的一些新型的桥式,如全索桥,索托桥,斜拉2悬吊混合体系桥、索桁桥等等。其中,悬索桥和斜拉桥是大跨径桥梁发展的主流。近20 年来发展最快的大跨径桥梁是斜拉桥,而遥遥领先的是悬索桥。当前世界最大跨度的悬索桥是1998年建造的日本明石海峡大桥,其主跨度为1991m;世界最大跨度的斜拉桥是1999 年建造的日本多多罗桥,其主跨度为890 m;而中国最大跨径的悬索桥是江苏润杨长江公路大桥,主跨度1490m,在世界悬索桥行列中位居第三;中国最大跨径的斜拉

3、桥为江苏南京长江第二大桥,主跨度628m,在世界钢箱梁斜拉桥中位列第三;湖北荆州长江公路大桥,主跨径达500 m,在世界预应力混凝土斜拉桥中位列第二。目前的桥梁技术已经能较好的解决现存问题,但是随着桥梁跨度不断增大,向着更长、更大和更柔方向发展,为了保证其可靠性、耐久性、行车舒适性、施工简易性和美观性及其统一还有大量的工作要作。桥梁工程结构设计的过程也就是如何处理桥梁结构的安全性(可靠性、耐久性) 、适用性(满足功能要求及行车舒适性) 、经济性(包括建设费用和维修养护费用) 及美观性的过程。传统的桥梁结构设计,要求设计者根据设计要求和实践经验,参考类似的桥梁工程设计,通过判断去构思设计方案,然

4、后进行强度、刚度、和稳定等各方面的计算。但由于设计者经验的限制,确定的最终方案往往不是理想的最优方案,而仅为有限个方案中接近最优的可行方案。桥梁结构优化理论是传统桥梁结构设计理论的重大发展,也是现代桥梁设计的目标。它是使所有参与设计计算的量部分以变量出现,在满足规范和规定的前提下,形成全部结构设计的可行方案域,并利用数学手段,按预定的要求寻求最优方案。2 大跨度桥梁的优化设计局部最优虽不能等同于整体最优,但却有益于整体最优,并促进桥梁结构的发展。因为对局部的优化设计变量相对较少而使研究的难度大大减小,研究的深度因而能更透彻。目前对大跨度桥梁的局部结构优化研究已涉及到大跨度桥梁结构设计及施工的各

5、个方面,主要有:（1）加劲梁横截面的优化大跨度桥梁的加劲梁主要有钢梁、混凝土梁、混合梁和叠合梁。根据目前全世界己建成的大跨度桥梁统计,跨度分别排在前12 位的斜拉桥和悬索桥,其主跨加劲梁形式大多为钢梁,而钢与混凝土结合梁和混凝土梁较少且跨度相对较小。（2）斜拉索或主缆的动力优化目前的大跨度桥梁主要有斜拉桥、悬索桥及其它的一些新型的桥式,如全索桥,索托桥,斜拉-悬吊混合体系桥等。这些桥式都有一个共同的特点,即都由缆索支承,且桥面较柔,属柔性结构,阻尼低。在外部激励下,拉索极易发生意想不到的大幅振动。如风雨共现时的风雨振现象,主梁和拉索之间耦合振动引起的参数共振、拉索的自激振动等。拉索的大幅振动容

6、易引起拉索锚固端的疲劳、降低拉索的使用寿命,严重时甚至对桥梁安全构成严重威胁。因此,大跨度桥梁的动力问题显得尤为重要。（3）索力调整优化大跨度桥梁的收缩徐变、非线性性条件等影响会随着跨度的增大越来越显著,但最终控制主梁应力和线形的直接因素还是斜拉索力和施工时的立模标高,因而确定合理的索力对斜拉桥的材料用量及结构安全性都有十分重要的意义。然而斜拉桥作为一个高次超静定结构,施工中又要经过体系转换,如何确定合理的成桥索力,同时又能保证施工中的塔梁受力均匀合理,是目前进行斜拉桥施工监测控制的主要目标。国内外对索力调整优化的研究进行得较早,发展得也较为成熟。目前,有关索力调整的理论主要有4 大类:a)

7、指定受力或位移状态的索力优化,如刚性支承连续梁法和零位移法。b) 无约束的索力优化,如弯距平方和最小法和弯曲能量最小法。c) 有约束的索力优化,如用索量最小法。d) 影响矩阵法。影响矩阵法能得到不同目标函数、不同加权的优化结果,又能计入预应力、活载、收缩徐变、约束优化等影响,既可用于确定索结构合理状态,也可用于施工阶段和成桥阶段的索力调整,实现了结构调整与结构优化的统一。影响矩阵法包含了前3 种优化方法,是目前最为完备的一种斜拉桥索力优化理论。（4）索塔的结构优化索塔的优化主要是塔高和受力合理性的优化。塔太高会给施工带来困难,增加造价。而塔太矮会降低拉索的工作效率,增加主梁和拉索的受力。因此单

8、独对塔高的优化不一定是经济的,而应和其它部分结合起来考虑。塔的受力合理性与塔的结构形式、缆索形式、缆索锚固形式及锚固点分布有关,也是一个值得研究的课题。（5）斜拉索和吊索锚固的优化斜拉索和吊索锚固的形式和锚固点的布置对索塔和主梁的应力集中问题和结构形式有一定的影响,应和索塔和主梁结合起来考虑。（6）悬索桥锚锭的优化悬索桥的锚锭有自锚式和地锚式。自锚式一般只有在无法使用地锚式时才采用。地锚的优化涉及到地质条件问题,目前研究较少。自锚式一般很少采用,研究也很少。（7）桥墩及基础优化对于大跨度桥梁桥墩和基础的优化,不论数量、位置、还是结构形式,一般都受地质条件的限制,应针对具体桥梁来考虑。因此,大跨

9、度桥梁的桥墩优化设计一般都是独立的,受上部结构影响很小。三、大跨度桥梁结构设计 上部构造形式的选择，应结合桥梁具体情况，综合考虑其受力特点、施工技术难度和经济性。简支空心板结构的桥型，施工方便，施工技术成熟；但跨径小，梁高大；由于桥梁跨径受限制，往往造成跨深沟桥梁高跨比不协调，美观性差；上部构造难以与路线小半径、大超高线形符合，且高墩数量增加；桥面伸缩缝多，行驶条件差。因而，在山区大跨度中，该类桥型一般用于地形相对平缓、填土不高的中、小桥上。预制拼装多梁式T梁在中等跨径桥中具有造价省、施工方便的特点，其造价低于整体式箱梁，是中等跨径直梁桥的常用桥型。但对于曲线梁来说，T梁为开口断面，抗扭及梁体

10、平衡受力能力均较箱梁差，曲梁的弯矩作用对下部产生的不平衡力大。但当曲线桥的弯曲程度较小时，曲线T梁桥采用直梁设计，以翼缘板宽度调整平面线形，可减少曲梁的弯扭作用，在一定程度上可弥补曲线T梁桥受力和施工上的不足。虽然直线设置的曲线桥仍有部分恒载及活载不平衡影响及曲线变位存在，但较曲线梁小。此外，可以采取加强横向联系的措施，提高结构的整体性。对于大跨径桥梁，最好采用悬臂浇筑箱梁。但是对于中等跨径的桥梁，箱梁桥不论采取何种施工方式，费用都较高，与预制拼装多梁式T梁相比，处于弱势。 下部结构应能满足上部结构对支撑力的要求，同时在外形上要做到与上部结构相互协调、布置均匀。桥墩视上部构造形式及桥墩高度采用

11、柱式墩、空心薄壁墩或双薄壁墩等多种形式。柱式墩是目前公路桥梁中广泛采用的桥墩形式，其自重轻，结构稳定性好，施工方便、快捷，外观轻颖美观。对于连续刚构桥，要注意把握上下部结构的刚度比，减小下部结构的刚度比，减小下部结构的刚度，可减小刚结点处的负弯矩，同时减小桥墩的弯矩，也可减小温度变化所产生的内力。但是桥墩也不可以太柔，否则会使结构产生过大变形，影响正常使用，并不利于结构的整体稳定性。对于高墩，除了要进行承载能力与正常使用极限状态验算外，还要着重进行稳定分析。对于连续梁结构或连续刚构桥，各墩的稳定性受相邻桥墩的制约影响，应取全桥或至少一梁作为分析对象。稳定分析的中心问题就是确定构件在各种可能的荷

12、载作用和边界条件约束下的临界荷载，下面以连续梁为例进行说明。介于梁、墩之间的板式橡胶支座，梁体上的水平力H(车辆制动力和温度影响力等)是通过支座与梁、墩接触面上摩阻力而传递给桥墩的，它不但使墩顶产生水平位移，而且板式橡胶支座也要产生剪切变形。当梁体完成水平力的传递以后，梁体暂时处于一种固定状态，但由于轴力及墩身自重的影响，墩顶还会继续产生附加变形，这就使得板式支座由原来传递水平力的功能转变为抵抗墩顶继续变形的功能，支座原来的剪切变形先恢复到零，逐渐达到反向的状态。 四、结语 大跨度作为公路工程的一部分，很多方面需要探讨。大跨度方案的确定应遵循“安全、舒适、经济、美观”的原则，只有把握好规律，抓

13、住侧重点，高速桥梁的布置和设计才能准确无误。 本文转自论文发表,原文地址 （英文版 ） Two regulations promulgated for implementation is in the party in power for a long time and the rule of law conditions, the implementation of comprehensive strictly strategic plan, implementation in accordance with the rules and discipline to manage the pa

14、rty, strengthen inner-party supervision of major initiatives. The two regulations supporting each other, the adhere to a positive advocate, focusing on morality is of Party members and Party leading cadres can see, enough to get a high standard; around the party discipline, disciplinary ruler requir

15、ements, listed as negative list, focusing on vertical gauge, draw the party organizations and Party members do not touch the bottom line . Here, the main from four square face two party rules of interpretation: the first part introduces two party Revised regulations the necessity and the revision pr

16、ocess; the second part is the interpretation of the two fundamental principles of the revision of laws and regulations in the party; the third part introduces two party regulations modified the main changes and needs to grasp several key problems; the fourth part on how to grasp the implementation o

17、f the two regulations of the party. and revised the necessity and revised history of the CPC Central Committee the amendment to the Chinese Communist Party members and leading cadres honest politics several guidelines and column 1 by 2015 to strengthen party laws and regulations focus. Two party reg

18、ulations revision work lasted a Years, pooling the wisdom of the whole party, ideological consensus, draw historical experience, respect for the wisdom of our predecessors, which reflects the unity of inheritance and innovation; follow the correct direction, grasp the limited goals, adhere to the pa

19、rtys leadership, to solve the masses of the people reflect a focus on the problem. The new revision of the and , reflects the partys 18 and the eighth session of the third, the spirit of the fourth plenary session, reflecting the experience of studying and implementing the General Secretary Xi Jinpi

20、ng series of important speech, reflects the partys eighteen years comprehensive strictly practice. (a) revised two regulations of the party need of in based on revised, the promulgation and implementation of January 2010, to strengthen the construction of the contingent of leading cadres play an imp

21、ortant role. But with the party to manage the party strictly administering the deepening, has not been able to fully meet the actual needs. Content is too complicated, eight prohibition, 52 are not allowed to hard to remember, and also difficult to put into practice; the second is concisely positive

22、 advocated by the lack of prohibited provisions excessive, no autonomy requirements; the third is banned terms and discipline law, both with the party discipline, disciplinary regulations repeat and Criminal law and other laws and regulations repeat; the fourth is to clean the theme is not prominent

23、, not for the existing problems, and is narrow, only needle of county-level leading cadres above. is in 1997 based on revision, in December 2003 the promulgation and implementation, to strengthen the construction of the party play very important role. Along with the development of the situation, whi

24、ch many provisions have been unable to fully meet the comprehensive strictly administering the practice needs. One is Ji law, more than half of the provisions and criminal law and other countries laws and regulations Repetition; two is the political discipline regulations is not prominent, not speci

25、fic, for violation of the party constitution, damage the authority of Party Constitution of misconduct lack necessary and serious responsibility to pursue; third is the main discipline for the leading cadres, does not cover all Party members. Based on the above situation, need to and the two is like

26、ly to be more relevant regulations first amendment. By revising, really put the authority of Party discipline, the seriousness in the party tree and call up the majority of Party members and cadres of the party constitution of party compasses party consciousness. (II) two party regulations revision

27、process the Central Committee of the Communist Party of China attaches great importance to two regulations revision . Xi Jinping, general books recorded in the Fifth Plenary Session of the eighth session of the Central Commission for Discipline Inspection, on the revised regulations made clear instr

28、uctions. According to the central deployment, the Central Commission for Discipline Inspection from 2014 under six months begin study two regulations revision. The Standing Committee of the Central Commission for Discipline Inspection 4 review revised. Comrade Wang Qishan 14 times held a special mee

29、ting to study two regulations revision, amendment clarifies the direction, major issues of principle, path and target, respectively held a forum will listen to part of the province (area) secretary of the Party committee, Secretary of the Discipline Inspection Commission, part of the central ministr

30、ies and state organs Department The first party committee is mainly responsible for people, views of experts and scholars and grassroots party organizations and Party members. Approved by the Central Committee of the Communist Party of China, on 7 September 2015, the general office of the Central Co

31、mmittee of the Party issued a notice to solicit the provinces (autonomous regions, municipalities) Party, the central ministries and commissions, state ministries and commissions of the Party (party), the General Political Department of the military, every 3 people organization of Party of two regul

32、ations revision opinion. Central Commission for Discipline Inspection of extensive solicitation of opinions, careful study, attracting, formed a revised sent reviewers. In October 8 and October 12, Central Committee Political Bureau Standing Committee and the Political Bureau of the Central Committe

33、e After consideration of the two regulations revised draft. On October 18, the Central Committee of the Communist Party of China formally issued two regulations. Can say, two laws amendment concentrated the wisdom of the whole party, embodies the party. Second, and revision of the basic principles o

34、f two party regulations revision work and implement the partys eighteen, ten eight plenary, the spirit of the Fourth Plenary Session of the Eleventh Central Committee and General Secretary Xi Jinping important instructions on the revised and , highlighting the ruling party characteristics, serious d

35、iscipline, the discipline quite in front of the law, based on the current, a long-term, advance as a whole, with Bu Xiuding independent and . Main principle is: first, adhere to the party constitution to follow. The constitution about discipline and self-discipline required specific, awaken the part

36、y constitution of party compasses party consciousness, maintaining the authority of the constitution. General Secretary Xi Jinping pointed out that no rules, no side round. Party constitution is the fundamental law, the party must follow the general rules. In early 2015 held the eighth session of th

37、e Central Commission for Discipline Inspection Fifth Plenary Session of the 16th Central Committee, Xi Jinping again pointed out that constitution is the party must follow the general rules, but also the general rules. the revision of the and is Method in adhere to the regulations established for th

38、e purpose of combining rule of virtue is to adhere to the party constitution as a fundamental to follow, the constitution authority set up, wake up the party constitution and party rules the sense of discipline, the party constitution about discipline and self-discipline specific requirements. 4 sec

39、ond is to adhere to in accordance with the regulations governing the party and the party. The Party of rule of virtue de, mainly refers to the partys ideals and beliefs, excellent traditional style. The revised the closely linked to the self-discipline, insisting on the positive initiative, for all

40、members, highlight the vital few, emphasized self-discipline, focusing on the morality, and the majority of Party members and the ideological and moral standards. The revised Ji method separately, Ji, Ji Yan to Method, as a negative list, emphasizing the heteronomy, focusing on vertical gauge. Is th

41、is one high and one low, a positive reaction, the strict party discipline and practice results transformation for the integration of the whole party to observe moral and discipline requirements, for the majority of Party members and cadres provides benchmarking and ruler. Third, insist on to. In vie

42、w of the problems existing in the party at the present stage, the main problems of Party members and cadres in the aspect of self-discipline and abide by the discipline to make clearly defined, especially the partys eighteen years strict political discipline and political rules, organization and dis

43、cipline and to implement the central eight provisions of the spirit against the four winds and other requirements into Disciplinary provisions. Not one pace reachs the designated position, focusing on in line with reality, pragmatic and effective. After the revision of major changes, major changes i

44、n the and modified and needs to grasp several key problems (a) adhere to according to regulations governing the party and party with morals in combination, for at the present stage, the leadership of the party members and cadres and Party members in existing main problems of self-discipline, put for

45、ward principles, requirements and specifications, showing Communists noble moral pursuit, reflected at all times and in all over the world ethics from high from low 5 common requirements. One is closely linked to the self-discipline, removal and no direct relation to the provisions of . the second i

46、s adhere to a positive advocate, eight prohibition 52 are not allowed to about the content of the negative list moved into synchronization amendment . Three is for all the party members, will apply object from the leadership of the party members and cadres to expand to all Party members, fully embod

47、ies the comprehensive strictly required. The fourth is prominent key minority, seize the leadership of the party members and cadres is the key, and put forward higher requirements than the ordinary Party members. Five is to simplify, and strive to achieve concise, easy to understand, easy to remember. The revised is the ruling Party since the first insists on a positive advocate forAll Party members and the self-discipline norms, moral declaration is