橋梁畢業(yè)論文中英文摘要.doc

摘 要：呂利高架橋的創(chuàng)新設計提出了一種輕型結構和透明的三角交叉預制圓管，這種結構完全從節(jié)點區(qū)無線條作出。其結果是雙空間桁架，以42.75米的典型跨徑。每個橫向三角形截面為2.9米和4.0米寬，是由一個細長橋墩支持。最大的直徑和管壁厚度超過500毫米和70毫米，相差很大。第一期間的連接設計的主要困難是確定復雜交叉沿管周長的應力分布，并計算支點應力。幾何計算，精密切割和邊緣管的準備是必要的設計，橋身充滿穿透焊縫。移動模架，這也確保了在混凝土澆筑，也需要特殊考慮的管狀桁架的穩(wěn)定。本文介紹了從設計演變的項目，桁架加工和焊接，到施工現(xiàn)場的步驟。引言在瑞士A1高速公路，1000米長的呂利高架橋，空間管桁架制造，是一個工程師設計比賽的結果。該項目選擇了由它的獨創(chuàng)性和審美素質(zhì)陪審團。在過去，沒有人敢來建造與焊接動態(tài)應力管節(jié)點的道路橋梁。設計爭論附近的村莊位于在弗里堡州，分為公路高架橋從東到西運行瑞士格中。穿越山谷的濕農(nóng)村單位土地和樹木所包圍，這座橋?qū)⑼瓿捎谝寥A東之間與穆爾登公路連接。弗里堡州公路處，有3個項目之間的選擇由選定的有經(jīng)驗的咨詢公司提交的。該設計必須遵循下列條件：-橋梁總長度：約1000米-橋面寬度：從原來的13.25米至16.00米（每個交通方向）-為了維護原因，會議決定建立兩個獨立的道路-縱傾角：2.9和3.6%之間的一個凹角與40000米半徑圓弧-水平曲線：2日期間過渡的3000米半徑圓-橋高：4至15米下列項目已提交給審核團的5名成員：-一預應力的44.60米和一個2.50米，平均高度的連續(xù)混凝土箱形梁-一預應力42.50米的大跨度混凝土箱形梁，平均這梁深度變化2至2.45米-之一，對42.75米和一個身高3.75米，平均跨度不斷復合空間桁架第三個項目是建議由它的“輕”，并允許它融入農(nóng)村氛圍。該建議是由負責當局批準的。該項目提交的咨詢工程師小組迪愛生- DMA的（多納Ingnieurs Conseils SA和Devaud，蒙加蒂等Associes SA），接受了這一創(chuàng)新的設計挑戰(zhàn)概念設計：周圍的樹木形狀啟發(fā)了筆者的概念設計1。此類樣式，可與鋼結構的元素小的地方可以很容易地改變和適應生活的承載能力2。三種不同截面的考慮：第一種選擇是理想的設計。它沒有超薄圓柱墩支撐，但不注重兩個分開的道路維修情況。第三個解決方案已經(jīng)設計，避免侵占周圍的樹木。這包括連接在橋墩上的兩縱截面桁梁垂直。其結果是一個三維管狀桁架支撐結構。工程項目的說明幾何結構：桁架的尺寸是根據(jù)等邊三角形。相對于傳統(tǒng)的箱形梁，桁架深度為50以上。這個輕量級的上層建筑長細比約是13：20，而不是常規(guī)意義上的梁的長細比（圖3）。幾何桁架首先考慮跨長以及可移動的最大因素。然后，管徑作了初步的計算和考慮了下列因素：對角線范圍內(nèi)的其它鋼管的大小。初步分析，選擇了267毫米和壁厚11至50毫米直徑的對角線。再加上在節(jié)點的幾何條件下，較低的最小直徑為508毫米。這有利于使用盡可能小的管道，以改善兩者對角線較厚的墻壁的傳力。低下弦和25至50毫米的各種管的厚度。在支持區(qū)域的厚度增加至50至70毫米。薄壁管的厚度有559毫米，以長2米的直徑為中心。較難的加勁因此可避免。這些節(jié)點上的弦角比較復雜（金形接頭）。該管大小的選擇取決于更多的超過實際的力量，這是最后階段板坯主要的考慮因素。1、節(jié)點交點在未考慮到具體的阻力時達到平衡。由于重疊的對角線，因此選擇以對角線之間傳輸?shù)拇怪苯Y構連接。2、該管的直徑必須足夠大，以提供足夠的剪力用于連接件的焊接，使其達到最小的空間和最小混凝土保護層。遇到的困難之一是在空間管狀結構制作中的管相貫焊接及周邊焊根滲透的檢查。即使結構不是太疲勞，但擔心結構失衡或嚴重焊接質(zhì)量差的緊張是可以理解的?；谶@個原因，焊接支持的審核獲得通過。這增加了內(nèi)部焊趾的寬度。支撐桁架是由較小的管建成，因為他們受力較低。其直徑弦之間變化在219.1和323.9毫米之間，所有對角線的管狀結構是168.3毫米直徑管的。橋面寬度在不等標高的12.0和14.65米之間。為了限制比較寬（4.0至5.33米）的懸臂的長期撓度，并盡量減少橋面板的重量，結構（600平方毫米）使用了橫向筋。甲板縱向預應力筋與其同一類型?？v向預應力筋已被選定，以保證在每個橋面板下的恒載（混凝土路面和部分壓縮）。設計：這座橋的設計是根據(jù)瑞士標準新160。擁有兩種不同的結構模型，可用于空間桁架計算：1、與結構安全設計的不斷和弦棚對角線2、疲勞和可維護性剛性節(jié)點設計橋面已成為一個平面網(wǎng)格模型（空腹轉(zhuǎn)換），兩個縱向弦，并在與空間桁架采用等效位移理論，以確定縱向弦剛度。甲板剛度，與上弦和圣維南扭矩阻力復合效應被認為是垂直成員屬性。接頭：對各部分和關鍵的結構安全進行了驗證與鉸鏈模型（討論的內(nèi)力3）。沒有標準的建議可以檢查、計算局部的抗疲勞性，或進行了實證方法并強調(diào)在圓形空心管交集。下列標準獲得通過后，委托方和專家工程師討論1、根據(jù)SIA標準的疲勞載荷1602、內(nèi)力計算距-充分和破獲組合截面距有n（= Esteel / Econcrete = 10）-剛性節(jié)點、關鍵字：美學，橋梁，組合結構橋梁，空間桁架，圓形空心管，疲勞應力，應力分布，應力集中系數(shù)，熱點應力，焊接AbstractThe innovative design of the Lully viaduct proposes a light and transparent structure made of a triangularcross-section fabricated entirely from unstiffened circular tubes. The result is twin space trusses, with a typicalspan of 42.75 m. Each transversal triangular cross-section is 2.9 m high and 4.0 m wide, and is supported by asingle slender pier. The largest diameters and thickness of the tubes are over 500 mm and nearly 70 mmrespectively. One major difficulty during the design of the connections was to define the stress distribution along the complex intersecting perimeters of the tubes, and to calculate the hot spot stresses. Geometry calculations, precision cutting and edge preparation of the tubes were necessary for performing full penetration welds. The mobile formwork, which also ensures the stability of the tubular trusses during concrete pouring, also required special consideration.This paper describes the evolution of the project, from design, truss fabrication and welding, to construction on site.INTRODUCTIONLocated on the Swiss highway A1, the 1000 m long Lully viaduct, made of space tubular trusses, is the result of an engineer design contest. This project was chosen by the jury for its originality and aesthetic quality. Inthe past, no one dared to build a road bridge with welded tubular nodes due to the dynamic stress.DESIGN CONTESTLocated near the village of Lully in the Canton of Fribourg, the viaduct is incorporated into highway A1 running from the East to West of Switzerland. Crossing a rural flat valley surrounded by wet land and trees,this bridge will complete a highway link between Murten and Yverdon. The owner, the Fribourg Cantonal Highway Office, had to choose between 3 projects submitted by selected experienced consulting firms.The partcipants had to respect the following conditions:Total bridge length : approximately 1000 mWidth of the bridge deck : from 13.25 m to 16.00 m in each traffic directionFor maintenance reasons, it was decided to build two separate roadwaysLongitudinal inclination : between 2.9 and 3.6 % in a concave circular arc with a radius of 40000 mHorizontal curve : circle of 3000 m between 2 transition radiusHeight over the valley : between 4 and 15 m.The following projects were submitted to the 5 members of the jury :One prestressed concrete box girder with an average span of 44.60 m and a constant depth of 2.50 m.One prestressed concrete box girder with an average span of 42.50 m. This girder depth varied between 2and 2.45 m.One composite space truss with an average span of 42.75 m and a constant height of 3.75 m.The third project was recommended by the jury for its “l(fā)ightness” and transparency allowing it to integrate into the countryside (Fig 1). The recommendation was approved by the responsible authority who accepted the challenge of innovative design. This project was presented by the consulting engineers group DIC-DMA (Dauner Ingnieurs Conseils SA and Devaud, Mongatti et Associes SA).CONCEPTUAL DESIGNThe shape of the surrounding trees inspired the author for the conceptual design 1. A certain analogy can be made with the steel construction where the elements size can be easily changed and adapted to live load capacity 2.Three different cross sections were considered :The first alternative was the ideal design (Fig.2). It has slim cylindrical piers without bracing, but did not respect the maintenance condition of two separated roadways. The third solution has been design to avoid having piers dominating the surrounding trees. This included perpendicular truss connecting the two longitudinal girders at the cross section on the piers. The result was a three-dimensional tubular truss supporting structure.PROJECT DESCRIPTIONGeometryThe dimensions of the trusses were based on equilateral triangles. Compared to a traditional box girder, the truss depth is 50% higher. The slenderness (L/H) of this lightweight superstructure is approximately 13 instead of 20 as for regular beam girder (Fig 3).The truss geometry was determined first by considering the span length as well as the maximum transportable element. Then the tube diameters were given by preliminary calculations and the following considerations:The diagonals governs the size of other members. Preliminary analysis leads to a diagonal diameter of 267mm and wall-thickness between 11 and 50 mm. Adding to this the geometric conditions at the nodes, thesmallest diameter for the lower chord was 508 mm.It was beneficial to use the smallest possible tube in order to improve the force transfer between diagonals due to the thicker walls . The thickness of the lower chord tubes varied between 25 and 50 mm (Fig 4). In the support zone the thickness is increased from 50 to 70 mm. The thicker walled tube has a diameter of 559 mm and a length of 2 m centered on the bearing. Unsightly stiffeners could therefore be avoided.The upper chords nodes are less complicated (K-shaped joint) (Fig 5). The choice of the tube size depended more on the considerations below than on the actual forces, which were carried mostly by the slab in the final stage.1. Nodal forces had to be equilibrated without taking the concrete resistance into account. Overlapping of the diagonals was therefore chosen in order to transfer some of the vertical force directly between the diagonals.2. The tube diameter had to be large enough to provide adequate space for the welded shear connectors and to allow minimum concrete cover.One of the difficulties encountered in the fabrication of the space tubular structure was the welding at the intersecting perimeters of the tubes and checking the penetration at the weld root. Even if the fatigue requirements are not too severe in road bridge construction, the fear of uncontrolled or bad quality weld roots in the tension tubes is understandable. For this reason, welding on backing shells was adopted. This increased the width of the inner weld toe.The brace truss at the piers were built with smaller tubes (Fig 6 and 7), as they are subject to lower forces. The diameter of their chords varied between 219.1 and 323.9 mm, all diagonals are made of 168.3 mmdiameter tube.The deck width varied between 12.0 and 14.65 m. In order to limit the long-term deflection of the relatively wide cantilever wings (4.0 to 5.33 m) and to minimize the weight of the deck, transversal tendons (600 mm2) were used. The concrete deck was prestressed longitudinally with the same type of tendons. Longitudinally the prestressing force has been chosen to insure compression in every section under dead load (concrete and road surface).DesignThe bridge was designed according to the Swiss standard SIA 160.Two different structural models were used for the calculation of the space truss:1. Hinged diagonals with continuous chords for structural safety design2. Rigid nodes for fatigue and serviceability designThe bridge deck had to be converted into a plane grid model (Vierendeel), made of two longitudinal chord and vertical members placed at the intersection with the diagon