本科橋梁專業(yè)畢業(yè)設(shè)計(jì).doc

本科橋梁專業(yè)畢業(yè)設(shè)計(jì)長(zhǎng)安大學(xué) 畢業(yè)設(shè)計(jì)（論文）任務(wù)書一 設(shè)計(jì)內(nèi)容（論文闡述的問(wèn)題）1 擬定橋型比較方案三個(gè)。2 擇優(yōu)推薦方案。3 進(jìn)行推薦方案上部結(jié)構(gòu)內(nèi)力分析，截面設(shè)計(jì)。4 進(jìn)行推薦方案的施工驗(yàn)算。二 設(shè)計(jì)原始資料（實(shí)驗(yàn)、研究方案）1 橋位地址剖面圖2 橋面設(shè)計(jì)標(biāo)高434.713 平曲線半徑R=4 縱坡i=05 單向橫坡i=2%三 主要技術(shù)指標(biāo)1 設(shè)計(jì)荷載：汽超20級(jí)。2 橋面凈寬：0.5+11.25+2.0+11.25+0.53 橋位氣溫：平均最底-12.3，最高+38.14 地震烈度：7度四 設(shè)計(jì)完成后提交的文件和圖表（論文完成后提交的文件）1 計(jì)算說(shuō)明書部分：1） 設(shè)計(jì)指導(dǎo)思想、重點(diǎn)、難點(diǎn)2） 各個(gè)方案的特點(diǎn)，推薦方案的被選理由3） 推薦方案上部結(jié)構(gòu)的結(jié)構(gòu)計(jì)算書、截面設(shè)計(jì)計(jì)算書4） 推薦方案施工驗(yàn)算書5） 施工中注意事項(xiàng)6） 設(shè)計(jì)小結(jié)2 圖紙部分：1） 方案比較圖2） 推薦方案整體布置圖3） 推薦方案施工示意圖4） 推薦方案上部結(jié)構(gòu)配筋構(gòu)造圖5） 細(xì)部構(gòu)造圖五 主要參考資料1.公路工程技術(shù)標(biāo)準(zhǔn)JTGB01-20032橋規(guī)3教材：橋梁工程、結(jié)構(gòu)設(shè)計(jì)原理、基礎(chǔ)工程、橋梁電算4與推薦方案相類似的手算實(shí)例。The Design of Luo-Xi Bridge,GuangdongGeneralThe Luo-Xi bridge,Guangdong,now under construction is a four lane highway bridge downstream of Zhu-Jiang River.The main bridge is designed jointly by Highway Planning and Design Institute,MOC and Highway Surveying,Planning and Design Institute,Guangdong.The whole bridge is constructed by Construction Division,Department of Communication,Guangdong Province.This bridge is at south part of Guangzhou city,across the Zhu-Jiang River.The width of the river is 461m,average depth of water 7.28m,average velocity of water 0.97m/sec.The bed is covered with sand of medium size,clay and weathered sandstone etc.,average thickness 19.2m.The bedrock is brown sandstone which has an average compressive strength 10MPa.The flow is steady and scouring of river bed is not great.Shipping boats are 50007000t,navigation width 120m,height 34m.Because the navigation is not closed at construction period,any construction equipment enter the navigation channel is not permitted.Three alternatives were considered in selecting the type of bridge.These are:continuous rigid frame bridge with main span of 180m,continuous grider bridge with mian span of 150m and cable stayed bridge with 2 pylons with mian span of 230m.As the persent trend is to eliminate expansion joints as well as bearings in the design of long bridges,after technical and economical comparison,the scheme of 65+125+180+110m continuous rigid frame is finally adopted in the design.The main bridge is 480m long with expansion joints provided only at its junctions with approaches,and the super-structure of the mian structure is completely integral with the piers to form a rigid frame.Single box is used for superstructure of main bridge.Height of box is 4m at bearing of No.2 pier,and 10m at bearing of No.3 and No.4 pier,and 3m at the closure section of the spans.Each of the two main piers in the river supporting the superstructure is composed of two reinforced concrete legs with dimension 2.28.0m,placed on pile cap immersed in water.The pier is supported by a group of 1.5m cast in situ reinforced concrete bored piles.No.2 pier rests on 12 bored piles each 24.2m long,and No.2、No.4 piers rest on 24 piles with average length of 47.3 and 27.1m respectively.To prevent damage of main pier due to ship collision double wall circular steel cofferdam with diameter of 28m at top and 23m at bottom are used around No.3 and No.4 pier serving as encircling structure of artificial island.Pot rubber bearings which allow only longitudinal displacement are provided at the end piers of main bridges to transmit lateral shear force.The general layout of whole bridge is shown in fig.1.ConcreteConcrete with 28 days strength of 50MPa is used for superstructure and No.2、No.3、No.4 pier walls,and concrete with strength of 30MPa is used for No.1、No.5 pier walls and pile caps,and concrete with strength of 25MPa is used for piles.Different test mixes of concrete are required to find the suitable consistency to facilitate the casting of concrete at deep bottom parts of box section in which the reinforced steel and prestressed tendon are densely distributed. Durability, appearance and watertightness of concrete shall conform to the appropriate requirements, and the requirement to remove the form one day after casting of concrete and to take load after three days of casting shall also be observed.Comprehensive tests shall be undertaken before construction to ascertain the modulus of elasticity as well as creep and shrinkage characteristic of concrete.Post tensioned tendon and prestressing systemPost tensioned tendon of superstructure is composed of wire strands and high strength bars.Table 1 gives the characteristic of the pretressed steel.The seven wire strand is supplied by VSL HongKong,and high strength bars domestic product.Table 1. Characteristies of Prestressing SteelItemsSeven wire strandsHigh strength barsNominal diameter (mm)12.832Nominal cross section(mm2)99804Ultimate strength(N/mm2)18651028Yield strength(N/mm2)1665765Relaxation(1000/h,20,initial stress is 0.7 ultimate strength)7%5%All the longitudinal pretressing tendons are 1912.8mm or 3112.8mm strands,anchored at one end by EC5-19 or EC5-31 VSL anchor respectively,which has ultimate tensile strength 3496kN and 5704kN respectively,and the tensile force adopted is 75% of ultimate tensile force.Frictional loss is rather small due to relative straightness of duct,hence the strands having length less than 70m are prestressed only at one end,and prestressed at both ends for longer length.The longest continuous tendon of main span exceeds 190m,which is the longest prestressed tendons used in our country.EC5-31 VSL anchor is used for transverse prestresssing, prestressed alternatively at distance center to center 100cm.Single or double32 finish rolled,deformed high strength bars ,spaced at 50cm cc.are used as vertical prestressed tendons of webs.Three way of prestress is used in this bridge,The domestic32 finish rolled,deformed high strength bars are used as vertical prestresssing bars,and VSL prestressing systems are used as longitudinal and transverse prestresssing strands.Six kinds of strands are used,which are strand at top slab,strand at bottom slab ,draped strand ,continuous strand ,post strengthening strand ,and temporary strand .Table 2 shows kinds and quantities of strands used at different locations.Table 2. Types、Kinds and Quantities of Strands at Different LocationsItems65m mid spanTop of No.2 pier125m mid spanTop of No.3、No.4 pier180m mid span110m mid spanStrand at top slab (EC5-31)2262Draped strand(EC5-31)88Continuous Strand (EC5-31)444444Strand at bottom slab (EC5-19)26304026Post streng thening strand(EC5-19)4444Temporary strand (EC5-19)2222The type of strand at top slab is determined by dividing the total required prestressing force at the end section by the effective prestresssing force of each strand and total number of segments and shall be 24.Strands bent vertically as well horizontally ,i.e.bent in space ,are used for longitudinal strands.Strands in top slabs have its anchorage concentrated at the haunches at top of web ,strands in bottom slabs shall be anchored as close to webs as possible.This will reduce local stress and at the same time transmit ,in a short path ,the concentrated prestressing force to the whole cross section.The complicated anchorage splays may be avoided by anchoring the top slab strands in the haunches.When the longitudinal strands at top and bottom slabs are shifted horizontal plane in order to anchor at given location ,it shall be shifted in a S curve to eliminate the lateral component of force induced at anchorage by the concentrated prestressing force .Allowance is provided for the deviation due to longitudinal vertical curve of deck ,and this is considered in the coordinates of strand ducts.Type and main dimension of section of superstructureAs the moment at pier section of superstructure due to dead load constitutes 84% of the total moment and the moment at closure section is only 5% of the total moment at pier section ,the main concept of selecting types and main dimension of section is to reduce dead weight and to increase the effective resisting capacity of cross sections ,The measures are:a. To reduce self weight and extra top and bottom slab area to accommodate great unmber of tendons ,large capacity VSL prestressing system is first introduced with jacking 4275kN.With the use of large capacity prestressing system ,the dimension of top and bottom slab are entirely governed by the loading requirement ,thus resulting in more than 60% saving in top and bottom slab sections compared with the 24 wire .Freyssinet system now in use. Besides the notable saving in cost ,it facilitates design and construction work ,and shortens the construction period.b. Use single box section with thin walls to increase moment of inertia per unit area. c. The height of closure section is selected as L/60 to reduces the dead weight but provides sufficient rigidity.d. The torsional rigidity of closed single box section is 60 times that of open section. The ratio of span to width is 11.6 .After accurate analysis ,it is found that torsion has only a little effect on internal force. Hence no diaphragm is used except at pier section ,this reduces dead weight and facilitates construction. Type of main pier Twin flexible legs of thin hollow box section are used as pier to provide greater longitudinal flexural rigidity and torsional rigidity in plane so as to accommodate for longitudinal moment produced by unbalanced construction loads as well as torsion in plane produced by lateral wind load during the cantilever construction of bridge. This type, twin flexible legs of thin hollow box section, uses 40% less concrete than solid section and has greater flexural rigidity and torsional rigidity than single column pier of the same cross sectional area, and ,in addition ,has less thrust resisting rigidity so that the internal forces due to temperature, creep and shrinkage are reduced.Type of foundationDue to the presence of a rather thick clay layer at No.3 pier of main bridge, bored piles have to be used, its diameter 1.5m,so determined by the equipment as well as experience of the constructing party.Structure of artificial islandThe designers paid good attention to the ship collision which had caused many serious damages. As is well known, the effective preventive measure is to construct artificial protective island around pier. After studying comprehensively the scouring of river bed, depth of water, the thickness and types of overlying soil, and the depth of rock layer, the designer concluded that it is feasible to use artificial island in this bridge, the reasons are:a. Height of double wall steel cofferdam, acting as encircling structure of artificial island, is only about 20m after taking account of navigation water level and scouring depth.b. The 19.25m high double wall steel cofferdam at No.4 pier can embed directly on rock layer which underlies at shallow depth, and the overlying layer above rock is medium and fine sand through which the cofferdam sinks without much difficulty. The rock layer at No.3 pier underlies at greater depth, but there is a layer of clay on top of rock and the cofferdam may rest at the desired depth in this layer. On top of clay layer there is also a layer medium and fine sand.Economical indexesPart of the economical indexes of this bridge is given in table 3.Table 3. Indexes per Square MeterItemsConcrete(m3)Strand(kg)Ordinary reinforcement(kg)Box girder of superstructure1.0966.5166.5Main piers No.2No.40.2136.17Side piers and foundation1.7171.73Total3.0166.5274.22Construction methodsThe double wall cofferdam is sunk to the design elevation by sand blowing and then is refilled to form the artificial island. The works about pile construction then proceed on the artificial island. No.2 pier is constructed by lifting from method while No.3 and No.4 piers are construcated by slip form method. The zero blocks(segment over pier support)are cast on falsework and brackets respectively. Two pairs of traveling carriages are used, enabling simultaneous carrying out by cast in place balanced cantilever segmental construction method on No.3 and No.4 piers. Design weight of each traveling carriages is 1088kN,maximum weight of load carried is 1784kN.There are 24 pairs of balanced cantilever casting work for each main T of No.3 and No.4 piers, ten working days of skilled labour are required for each operating cycle of 2 segments. The 20m and 30m length cast in place portions of the side span are poured on falsework.廣東洛溪橋主橋設(shè)計(jì)總體設(shè)計(jì)廣東落溪大橋是跨越珠江下游主航道的一座四車道公路橋。主橋由交通部公路規(guī)劃設(shè)計(jì)院與廣東省公路勘察規(guī)劃設(shè)計(jì)院共同設(shè)計(jì)，廣東省公路工程處施工。該橋位于廣州市南郊，橫跨珠江，江面寬461m，平均水深7.28m，平均流速0.97m/s。河床表面被中砂、淤泥和風(fēng)化巖等所覆蓋，平均厚度為19.2m?；鶐r為紅褐色泥質(zhì)砂巖，平均抗壓強(qiáng)度10MPa左右。河床沖刷不大。通航海輪5000噸級(jí)7000噸級(jí)。凈跨120m，通航凈高34m。由于在施工期間通航不能封閉，所以不允許任何施工設(shè)備進(jìn)入通航河道。有三種橋型方案可供選擇。這三種橋型方案是：主跨為180m的連續(xù)剛構(gòu)；主跨為150m的連續(xù)剛構(gòu)和主跨為230m的門式斜拉橋。根據(jù)當(dāng)前國(guó)際長(zhǎng)大橋向著無(wú)支座、無(wú)伸縮縫發(fā)展的趨勢(shì)，以及從技術(shù)經(jīng)濟(jì)上進(jìn)行比較，選定主橋結(jié)構(gòu)為65+125+180+110m的連續(xù)剛構(gòu)作為最終的設(shè)計(jì)方案。主橋全長(zhǎng)480m，除兩端與引橋連接處設(shè)置了伸縮縫外，在主橋全長(zhǎng)范圍內(nèi)，上部結(jié)構(gòu)與墩身的連接全部采用了整體結(jié)構(gòu)。主橋上部采用單箱單室，2號(hào)墩頂處梁高4m、3號(hào)和4號(hào)墩頂處梁高10m，在各跨合龍?zhí)幜焊?m。主墩采用截面尺寸為2.28.0m鋼筋混凝土空心雙柱墩。樁基用1.5m直徑的嵌巖樁，兩個(gè)主墩分別由樁長(zhǎng)47.3m和27.1m的24根樁組成。為了避免主墩因船舶撞擊而造成損壞，在主墩外圍設(shè)置了上部直徑為28m、下部直徑為23m的雙層鋼圍堰作為人工防撞結(jié)構(gòu)。在主橋兩端的邊墩上設(shè)置了只允許縱向位移的盆式橡膠支座。主橋的總體布置見(jiàn)圖1。混凝土上部結(jié)構(gòu)及2、3、4號(hào)墩墩身采用28天強(qiáng)度為50MPa的混凝土，1、5號(hào)墩墩身及各墩承臺(tái)采用30MPa，樁基采用25MPa混凝土。設(shè)計(jì)要求進(jìn)行不同配合比的混凝土試驗(yàn)，以便找出最佳配合比。同時(shí)要求有足夠的和易性，以便澆注到鋼筋和鋼束密布且很深的箱梁底部去。此外耐久性、外觀、水密性均應(yīng)滿足常規(guī)要求，也應(yīng)保證一天以后拆模和三天加載的標(biāo)準(zhǔn)。為了確定彈性模量和了解混凝土的收縮徐變特性，要求在施工前進(jìn)行綜合性的實(shí)驗(yàn)。后張預(yù)應(yīng)力體系上部結(jié)構(gòu)采用由鋼絞線和粗鋼筋組成的后張預(yù)應(yīng)力體系，表1給出了預(yù)應(yīng)力鋼材的特性。7絲一根的鋼絞線由香港VSL公司提供，粗鋼筋為國(guó)內(nèi)產(chǎn)品。表1 預(yù)應(yīng)力鋼材特性項(xiàng)目七絲鋼絞線粗鋼筋標(biāo)準(zhǔn)直徑(mm)12.832標(biāo)準(zhǔn)截面積(mm2)99804極限強(qiáng)度(N/mm2)18651028屈限強(qiáng)度(N/mm2)1665765100h,20松弛率(初始應(yīng)力為極限應(yīng)力的75%)7%=12mm II級(jí)螺紋鋼筋，直徑=12mm 級(jí)光圓鋼筋；錨具：XM錨或 OVM錨主要參考資料：1:土木工程專業(yè)畢業(yè)設(shè)計(jì)指南橋梁工程分冊(cè)2:橋梁工程 教材3:結(jié)構(gòu)設(shè)計(jì)原理 教材4:基礎(chǔ)工程 教材 5: 橋涵水文 教材6:橋梁計(jì)算示例集 人民交通出版社出版7:橋梁上部結(jié)構(gòu)計(jì)算示例(二) 重慶交通學(xué)院等校合編主要技術(shù)指標(biāo):JTJ 021-89公路橋涵設(shè)計(jì)通用規(guī)范 JTJ 022-85公路磚石及混凝土橋涵設(shè)計(jì)規(guī)范 JTJ 023-85公路鋼筋混凝土及預(yù)應(yīng)力混凝土橋涵設(shè)計(jì)規(guī)范 JTJ 024-85公路橋涵地基與基礎(chǔ)設(shè)計(jì)規(guī)范 方案比選序號(hào)方案類別 比較項(xiàng)目第一方案第二方案第三方案主橋：預(yù)應(yīng)力混凝土連續(xù)剛構(gòu)橋(75m+136m+75m) 預(yù)應(yīng)力混凝土連續(xù)梁（三跨）（80m+130m+80m） 預(yù)應(yīng)力混凝土連續(xù)梁橋（四跨）(55m+2x90m+55m)1橋高（m）434.71434.71434.712橋長(zhǎng) (m)2862902903工藝技術(shù)要求采用懸臂施工法在橋梁設(shè)計(jì)中要考慮施工過(guò)程中的受力狀態(tài)及由于體系轉(zhuǎn)換和其他因素引起的附加內(nèi)力.技術(shù)先進(jìn)，工藝要求較嚴(yán)格.但采用懸臂施工體系轉(zhuǎn)換較多，施工線形及合龍技術(shù)要求較高.需大噸位支座.技術(shù)先進(jìn)，工藝要求較嚴(yán)格.但采用懸臂施工體系轉(zhuǎn)換較多，施工線形及合龍技術(shù)要求較高.需大噸位支座.4施工難易程度橋梁上部采用掛籃懸臂澆注施工，施工時(shí)要對(duì)稱澆注，應(yīng)注意立摸高程的合理設(shè)置，準(zhǔn)確控制懸澆高程，施工要求較高.采用掛籃懸臂澆注施工；不需大量施工支架和大型臨時(shí)設(shè)備，不受跨數(shù)限制，橋梁施工受力狀態(tài)與運(yùn)營(yíng)受力狀態(tài)基本相近.采用掛籃懸臂澆注施工；不需大量施工支架和大型臨時(shí)設(shè)備，不受跨數(shù)限制，橋梁施工受力狀態(tài)與運(yùn)營(yíng)受力狀態(tài)基本相近.5橋型特點(diǎn) 主墩無(wú)支座，施工無(wú)體系轉(zhuǎn)換，伸縮縫少，行車舒適性好，順橋向抗彎剛度和橫向抗扭剛度大，受力性能好.順橋向抗推剛度小，故能有效地減小溫度、混凝土收縮徐變和地震影響.有利于養(yǎng)護(hù)維修.結(jié)構(gòu)受力性能好，變形小，伸縮縫少，行車平順舒適，造型簡(jiǎn)潔美觀，養(yǎng)護(hù)工程量小，抗震能力強(qiáng).主墩有支座，順橋向抗彎剛度和橫橋向抗扭剛度小，不利于懸臂施工的橫向抗風(fēng)要求.結(jié)構(gòu)受力性能好，變形小，伸縮縫少，行車平順舒適，造型簡(jiǎn)潔美觀，養(yǎng)