原创】钢箱梁桥设计_桥梁工程毕业论文设计

1、1. 绪论32. 设计概述42.1桥孔布置52.2截面尺寸及拟定5223箱梁面板厚度设置 62.2.4箱梁腹板宽度设置73. 主梁截面几何特性计算74主梁内力计算84.1恒载内力计算84.1.1 一期恒载内力94.1.2二期恒载内力104.1.3总恒载内力.11.4.2活载内力计算124.2.1横向分布系数的计算 124.2.2主梁内力影响线及加载 134.3内力组合204.3.1承载能力极限状态205. 第二体系的计算215.1桥面板的局部应力计算215.2截面几何特征值的计算225.3纵横肋的弯矩计算 265.3.1活载的弯矩计算 265.3.2恒载的弯矩计算275.3.3横肋弹性变形附加

2、弯矩计算285.4纵肋截面的应力计算306. 应力检算31小结33参考文献34致谢35附录A36BRIDGE TO THE FUTURE 36桥梁走向未来 45171. 绪 论世界上第一钢箱梁桥是 1850 年英国建造的 britania 铁桥路桥。该桥架设在Conway-Britania 间的 Menai 海峡上，跨度 142m。可是由创始人 George Stephenson 提出的薄避闭口截面形式的桥梁在 1 00年间却很少再被采用。 第2次世界大战后， 在西德，随着对被炸毁的莱茵河桥修复工程的展开，在 50 年代初期接连假设了 若干近代的箱梁桥，打破了 Britania 桥的跨长记录。

3、箱梁桥的飞速增加主要是由 于下述理由： 由于箱梁桥的抗扭刚度和抗扭强度均较大，适用于曲线桥。直线桥在偏 心活荷载作用下， 其横向的荷载分配是良好的。 即在单室箱梁桥中， 两个腹板弯 曲应力相差很少，上下翼缘弯曲应力也几乎相等。 箱梁桥的翼缘宽度要比工形截面板梁桥大的多。因而，薄的翼缘也能很 好的抵抗弯曲应力。 工形板梁桥随着跨度加大， 翼缘板要加厚， 且需要高强度钢， 从而连接就困难了。 而箱梁因为翼缘薄这就不成其为问题了。 一般来讲， 箱梁和 同跨度工形梁桥相比， 梁的高度低。 且有轻快美感。 梁高跨比较小就具有十分是 用的价值。 进来，随着安装机械大型化，分块架设法正在迅速发展。箱梁适于用

4、分 块架设安装，可以提高安装效率，缩短工期。 从箱梁的结构来看，无论是承受竖直偏心荷载，都能作为一个空间结构 来抵抗外力， 能发挥各个杆件的理学性能， 没有所谓的零杆。 箱梁在所有荷载作 用下，各杆件按空间结构力分担作用力， 一个杆件可以起几种作用。 箱梁上翼缘 起的作用有：钢桥面板作用，将车轮荷载传递给主梁；在竖直荷载作用下， 作为主梁翼缘抵抗弯曲；在偏心荷载作用下，作为闭口薄壁截面抵抗扭转。另一方面，下翼缘除了起、作用外，在水平荷载作用下，还起平纵联作用。因而力学性能好，设计可达到经济的效果。 箱梁的内部作为维修管理用的通道是很和使得不需要特殊的脚手架便 可在内部进行观察、油漆和补修。 电

5、缆、水管、煤气管等附属设备容易在箱梁内部通过。 箱梁不是密封的，与外面大气隔绝，不和海边、河上的湿气接触，有利 于防止锈蚀。 由于加劲杆、 横联、节点板等几乎全设置在内部， 箱梁外部显得很平滑。 因而维修管理，油漆作业很容易，灰尘难以滞留，外观轻巧美观。 由于梁的高度低，整个结构纤细，轻快而优美。 连续钢箱梁桥的截面形式很多，一般应根据桥梁的跨径、宽度、梁高度、 支撑形式、 总体布置和施工方法等方面综合确定， 合理选择主梁的截面形式， 对 减轻桥梁自重、 节约材料、 简化施工和改善截面受力性能是十分重要的。 目前连 续钢箱梁桥的截面形式主要有：板式、肋梁式和箱形截面梁。其中，板式、肋梁 式截面

6、构造简单、 施工方便， 箱形截面具有良好的抗弯和抗剪性能， 是预应力混 凝土连续梁桥的主要截面形式。本设计采用箱（单厢三室） ，主要出于以下几点 考虑：首先，箱形截面整体性好，结构刚度大；其次，抗扭能力强，同时箱形截 面能提供较大的顶板翼缘悬臂， 底板宽度相应较窄， 可大幅度减小下部结构工程 量。采用变高度主要是适应连续梁内力变化的需要。设计具体分为以下几步： 桥式方案的比选及施工方案拟定； 上部结构截面形式及截面尺寸的拟定； 上部结构截面几何特性计算； 上部结构计算图式及有限元单元的划分； 上部结构永久作用效应的计算（一期横载、二期横载分开计算） ； 上部结构可变作用效应的计算； 影响线计算

7、及绘制； 影响线加载； 上部结构内力组合的计算及包络图的绘制； 主梁的各项检算 承载能力极限状态强度计算 正常使用极限状态应力计算说明：本设计中影响线的绘制是通过 sp ap90来进行检验，通过本次设计， 对以前和专业知识进行了一次系统的复习， 加深了我的理论 知识和水平，但由于时间关系，设计中还存在不少问题，恳请各位老师斧正。2. 设计概述连续钢箱梁桥， 由于构造简单， 预制和安装方便， 在桥梁建设中得到了广泛 的应用。然而但这种简支体系的跨径超过 40-50m时，跨中恒载弯矩和活载弯矩 将会迅速增大， 致使梁的截面尺寸合自重显著增加， 这样不但材料耗费大， 并且 给施工带来困难。 因此，对

8、于向本设计的较大跨径的桥梁， 就宜采用在内力分布 方面较为合理的结构体系，本设计采用连续钢箱梁桥，连续钢箱梁桥由于跨越能 力大、施工方法灵活、适应性强、结构刚度大、抗地震能力强、通车平顺性好以 及造型美观等特点，目前在世界各地得到广泛的应用。2.1 桥孔布置本桥为连续钢箱梁桥，从已建桥梁实例的统计资料分析，跨径大于100m 的连续钢箱梁桥有 90%以上是采用变截面梁。因为大跨桥梁在外载荷自重作用 下，支点界面将出现较大的负弯矩，从绝对值来看，支点截面的负弯矩大于跨中 界面的正弯矩，因此采用变截面梁能负荷量的内力分布规律，另外变高度梁使梁体外型和谐，节约材料并赠大桥下净空。在跨径布置上，为了减少

9、便跨跨中正弯 矩，宜采用不等跨不止，这样便于施工。孔径为35m+45m+35m,实际桥长采用115m,桥梁结构计算图示见图2-1。图2-1桥梁计算图示2.2截面尺寸及拟定2.2.1截面形式及梁高主梁高度通常是通过技术经济比较确定的，应考虑经济、梁重、建筑高度以 及净空要求等，在标准设计中还应考虑标准化，提高梁的互换性。桥梁上部结构横截面采用变截面箱型截面，截面形式为单厢三室，主要出于以下几点考虑：首先，箱形截面整体性好，结构刚度大；其次，箱梁的顶、底板可以 提供足够活载变形；另外，抗扭能力强，同时箱形截面能提供较大的顶板翼缘悬 臂，底板宽度相应较窄，可大幅度减小下部结构工程量。箱形截面主要有顶

10、板、底板、腹板与加劲构件组成钢桥面板若仅考虑强度，则其厚度只需 6mm左右，但薄板的刚度过小，在 活载作用下自身变形过大，因此设计时桥面板不小于 10m m。此桥设计顶班、底 板均取14mm。此桥为6车道，设计荷载：城-A级，桥面较宽，荷载较大，应设计成单箱 多室箱梁桥合适，此桥采用单箱三室箱梁截面，此桥设计成 U 形闭口截面，内部截面纵肋受到保护，不易生锈板厚可用到 6mm。纵肋主要其起加劲作用，其间距与钢桥面板的厚度相关，此桥取300mm，底板也要设纵横肋，纵肋间距可校顶板纵肋间距大，取400mm；横肋于顶板位置相同，以组成横向联接系，增加横向刚度。箱梁设置一定数量的横隔板以增加其整体作用

11、。 横隔板的位置和尺寸由计算 而定，一般其间距可达10- 15m，在跨中和支承处必须设置横隔板， 此桥边跨的 横隔板间距为 2m。箱 梁 高 度 的 确 定 方 法 ： span will provid 50.5 m of vertical clearance,and the two towers will be situated away from the main navigation channel.The final component of Thailands new Outer Bangkok Ring Road, the eight-lane cable-stayed Chao

12、Phraya River Bridge, will not only alleviate Bangkoks notoriously each direction. The upper portion of each tower will enclosed chamber for cable anchors, a 1.5 m square opening at the bottom providing easy accessfor maintenance and inspection.For the past 20 years, Thailands capital, Bangkok, const

13、ructing expressways to lleviate traffic congestion. Among the major expressway projects in the capital is the Outer Bangkok Ring Road, a 170 km longleg-the Southern Outer BangkokRing Road, or S-OBRR-remains to be constructed. Scheduled for completion in 2007, the 21 km elevated viaduct will incorpor

14、ate four major interchanges and a cable-stayed bridge over the Chao Phraya River. With a main span of 500 m and two side spans of 220.5 m, the Chao Phraya River Bridge will be the longest in Thailand.In 1996 the Department of Highways retained a joint venture team of consultants to design the S-OBRR

15、. The design team included Asian Engineering Consultants (AEC), Thai Engineering Consultants (TEC), and Siam General Engineering Consultants, all of Bangkok; Oriental Consultants, of Tokyo; and Parsons Brinckerhoff (PB), of New York City. Once the joint venture was formed, designers began a feasibil

16、ity study of the Chao Phraya River crossing and set about determining the most suitable type of crossing. Tunnels and cable-stayed bridges were developed and evaluated. Eventually, 1999 engineers began to design the S-OBRR. The Chao Phraya River Bridge design was led by PB and supported by AEC and T

17、EC. Conceptual and preliminary designs were pre-pared by PBS New York staff, and Thai engineers working in Bangkok with the author completed the subsequent final design. The engineers established four design goals. They wanted a bridge that would (1) be long lasting and easily maintained, (2) enhanc

18、e the city architecturally, (3) be economical and incorporate the maximum amount of local material, and (4) not disrupt marine traffic theChao Phraya River during construction. Superstructure true that will carry four traffic lanes in each direction and provide 50.5 m of vertical clearance for marin

19、e traffic. The bridges two A-shaped towers will straddle the 500 m main span and will stand as stylized representations of the traditional Thai greeting, the each side will provide stability. The bridge features a symmetrical profile and slopes no more than 3 percent. The bridge was designed for 208

20、 KN loads from trucks-loads 30 percent those set forth by the American Association of State Highway and Transportation Officials in the 16th edition of its Standard Specifications for Highway Bridges (1996).The . The legs, each supported by two 24 by 24 by 4 m footings, join at the top to form a cha

21、mber for cable anchors. Decorative spheres 3 m in diameter and spires 8 m tall at the top of the towers will be gilded in traditional Thai style. The two towers-one located in shallow water on the east bank, the other behind a wharf on the west bank-will be situated away from the main navigation cha

22、nnel to eliminate the possibility of collisions with the bridge and ensure that marine traffic and wharf operations can proceed unimpeded.The three anchor piers will be situated behind each tower on the bridges back spans. The piers will maximize the vertical and lateral stiffness of the bridge supe

23、rstructure and the tensional stiffness of the main-span superstructure and will stabilize the bridge during strong winds. The A-shaped towers will also contribute to the tensional stiffness of the superstructure.Moment connections between the superstructure and the anchor piers eliminate the need fo

24、r wind locks, which attach the deck to the anchor piers and require special inspection and maintenance. The direct connection with the anchor pier will substantially reduce the stress range in the stay cables located adjacent to the pier and lessen the possibility of cable fatigue. Cables, not the m

25、ore commonly used bearings, will support the superstructure at the towers and reduce the negative bending moment in the edge girders at the towers under certain live-load conditions.The composite superstructure includes a rein-forced-concrete deck, steel floor beams, and two teel edge girders. A dec

26、k slab that varies in thickness from 260 to directly supports vehicle loads310 mm. The thicker slab segments will extend98.5 m from each tower in both directions. Recast deck panels will span between the floor beams but will not fully cover the top flanges of the beams. Cast-in-place (CIP) concrete

27、will be placed on top of the floor beams and the exposed portions of the, flanges to make the concrete deck composite with the steel-supporting frame. A 40 mm thick . To reduce stress in the overlay from Bangkoks the deck slab. Reinforcing bars will also be used as ties in the footings to resist lat

28、eral thrust between the inclined tower legs. Built-up I-shaped steel beams spaced 4 m apart will form the floor beams and will match the 1.625 m precast deck panels.The bridge is designed so that the superstructure of the main span can be erected by delivering the major structural components to the

29、deck from the towers. The box-shaped steel edge girders . With an inclined outside web and a vertical inside web, this 1.625 m to 2.2 m as they approach the ends to match the depth of the concrete box girders in the approaches.The top flange will be 1.5 m wide and the bottom flange will be 1.9 m wid

30、e. To make the concrete deck and steel edge girder composite, shear studs will be welded to the flange. Four rubber bumpers at the deck level of each tower are designed to transfer and can be replaced by a single person. Cable anchors are located inside the edge girder, which protects the cable-to-g

31、irder anchors from the elements. A circular access between the floor beams to provide easy access to the cable anchors for inspection and main- tenancy purposes. For aesthetic reasons, the bottoms of the girders , seven-wire welds less strands will support the bridge s superstructure. The strands ar

32、e 15 mmdiainmeter and conform to ASTM Internationals specification A412-90a for grade 270 strands. The bridge design incorporates the latest advancesfor protecting cable strands from corrosion, including galvanizing and coating individual strands with wax or grease and then sheathing them in a layer

33、 of polyethylene. The protected strands will be placed in a . Welded beads will be placed in a spiral pattern along the exterior surface of the HDPE pipes to control cable vibrations caused by wind and rain. Since the long cables (up to 260 m) are prone to large-amplitude vibrations, crossties-an ef

34、fective and economical method of controlling cable vibration-will be installed. The wind ties suppress individual cable resonance by forcing cables with different mode frequencies to vibrate together.The Post Tensioning Institute, based in Phoenix, requires that stay cables be replaceable. The engin

35、eers be replaced while traffic continues on two lanes in each direction. The bridge designed to allow for the accidental loss of any one cable without bridge failure.The bridge design includes a large chamber on each tower to the bottom slab will allow for the lifting of , inspection, maintenance, a

36、nd future cable replacement. Each anchor pier will consist of double columns. The 4 by 4 m and ensure a long service life. The two columns are tied on top for lateral stability. Cantilever arms will extend from the top of each column longitudinally, carrying the weight of the concrete counterweights

37、 before the anchor cables are installed. The cantilever arms will also increase superstructure stiffness and reduce bending moments in the edge girders. The concrete counterweights will eliminate uplift at the anchor piers and, in contrast to such commonly used tie-down devices, as steel rods, cable

38、s, and pins, require onlyminimal inspection and no maintenance.The bridge, like much of Bangkok, is located in a floodplain, and there is a 15 m layer of soft clay near the sites surface. To properly support the towers and anchor piers, engineers will drill shafts 2 m in diameter to a depth of 50 m.

39、 The engineers chose 2 m shafts because they possess the lateral bending capacity required for large foundations in soft soils. To facilitate inspection and maintenance, the designers provided easy access to all of the major structural components. No special equipment or falsework will be required t

40、o gain access to the superstructure, cable-to-tower connections, or cable-to-girder connections. A catwalk provides access to the area beneath the deck, and the bottoms of the edge girders will be accessible by means of a snooper-a specialized lift truck that extends under the bridge for maintenance

41、 and inspection.Because cable-stayed bridges tend to be the design. Linear analyses were performed for live loads, wind loads, and temperature loads; nonlinear analyses were performed for dead loads, cable replacements, and cable loss; dynamic analyses were performed for seismic loads and to compute

42、 eigenvalues for mode shapes and frequencies for wind tunnel testing; and a finite-element analysis was performed for the floor beam opening stress distribution. PIGLET-developed by the University of Western Australia to three dimensions-was used to compute the bending moments and axial forces in th

43、e drilled In addition to the computer tools used in the structural analysis, engineers paid careful attention to the engineering assumptions informing the design. They also trained a keen eye on the accuracy of the initial input data, keeping computer models as simple as possible to ease the data ve

44、rification process.Becausethe aerodynamic stability of long-span bridges is always a major concern, the engineers designed the A-shaped tower and anchor pier combination to achieve the greatest possible stiffness when connected with a flexible superstructure, thereby increasing aerodynamic stability

45、. Using a 1:60 sectional model, Rowan Williams Davies &Irwin, Inc., an engineering consulting firm inGuelph, Ontario, tested the bridges aerodynamic stability in a wind tunnel. The test measured static wind force and moment coefficients. The results were as follows: The design wind speed is substant

46、ially lower than the tested flutter speed, which means that the bridge is designed to endure those found at the project site. (Flutter is a self-excited aerodynamic instability that can increase to very large amplitudes with tensional or vertical motion.) The bridge designed to withstand a wind spee

47、d of 56 ms, a value with a 10,000-year return period.The bridge deck can experience vortex-shedding vibrations at 25 ms. The peak deck acceleration was found to be lower than the allowable specifications set forth in 1980 by ASCES Committee on Loads and Forces on Bridges. The bridge can withstand bu

48、ffeting-a random vibration caused by unsteady wind loading arising from turbulence. In particular, the test showed that the bridge is able to withstand wind load distributions period.The concrete, reinforcing steel, steel shapes, gratings, and HDPE pipes necessary for the S-OBRRS Chao Phraya River B

49、ridge will be produced locally. Only such specialty items as cable anchorages will be imported. Construction of the bridge began in August and is expected to be completed in early 2007, providing a badly needed solution to traffic problems and a structure that promises to add to the beauty of this b

50、ustling Asian metropolis.The piles. 40 in long and 3 m in diameter, arc driven into the sandy river bottom from above the water level. This foundation system was considered to be more effective than concrete piling because of the steel piles lateral stiffness and strength. Research was conducted int

51、o the possibility of improving the axial stiffness by means of pressure grout injection at the pile bottom. However, because this method applied in similar situations and because the operational risks were considered severe, the method was dropped in favor of increasing the depth of the piles.Prefab

52、ricated-concrete caissons measuring 25 by 10 in were installed on top of the piles at each pier location. Casting concrete underwater made the rigid connection between the piles and the caissons. The design of the piles and the bending connection was governed by the requirement that the structure wi

53、thstand a 30 MN ship impact at a level 3 m above the waterline and allow a lateral displacement of no more than 80 mm at the track level. Once the pile was pumped dry. Since the top of the casing is 0.5 m below the water level, temporary water retaining skirts were employed, and the cast with concre

54、te.On top of each casing a was cast in site. The shafts vary in tolerances as small as 10 mm. The top plane of each shaft, measuring just 5 by 6 m, included space for the vertical supports at the edges, jacks for bridge lifting, space accessible from the bridge deck.The acceptable vertical tolerance

55、 of the deck was set at15 mm, or 17000 of the span. Considering the length of the spans, the fact that the girder was continuous over multiple spans, and the composite nature of the structure, consultation with the rail authorities the acceptable tolerance was increased to 40 mm.The a tolerance of 5

56、 mm. Since the bridge site is between two existing bridges, the their upright position but on their sides. On the advance.The project also included the design and construction of approach structures on both ends of the crossing, because the trains may reach speeds of more than 300 km sea level in th

57、e tunnel north of the bridge to 20 m above mean sea level at the summit of the bridge, in the middle of the river. The alignment sea level.Ruchu Hsu, P.E., M.ASCE, is a supervising structural engineer for Parsons Brinckerhoff, Inc., in New York City. This paper was presented at the 21st Annual Inter

58、national Bridge Conference, which took place in Pittsburgh June 12-I6, 2004.桥梁走向未来过去 20 年里，泰国的首都曼谷 ,已经修筑高速道路以减轻交通拥挤。在这 些主要的高速道路之中， 位于首都的是曼谷外部的环形路， 一条 170 千米长环绕 这个城市的公路。这条路就快完全修完，只剩南边的东边一半，即：曼谷南面外 部的环形路还没有竣工 ,或者说是东南线 OBRR 还需要修建。 预计在 2007 年完 成,抬高的 21千米陆桥将会和四个主要的立交桥和一个斜拉桥位于Chao Phraya河川之上，由一个 220.5米的主跨和二个 500米的边跨组成 ,那 Chao Phraya 河川 桥将会是泰国的最长的桥梁。1996年，公路部共同投资队聘请顾问来设计 S-N线路OBRR。设计队伍 中有亚洲的工程顾问(AEC)，泰国工程顾问(TEC),还有来自暹罗的指挥工程顾 问，所有的、东方各国、东京、边区牧师(PB)和纽约的顾问共同组成了一支探险 队伍，设计师们开始对横跨 Chao Phraya 河川的可行性研究以及有关决定最适当 类型进行研究。 隧道和斜拉桥被提出而且评估。然而最后，越来越清楚地认识 到桥是最经济的 ,不会打扰航道交通 , 并且最好是把他发展成为公路立交桥。1999年，工程师们开始设计 S-N