【正文】 g the ponent. 3, Receive curved. Most near the large section from border is it appear and draw into direction vertical crack to begin person who draw curved square, and develop toward neutralization axle gradually. While adopting the whorl reinforcing bar , can see shorter secondclass crack among the cracks. When the structure matches muscles less, there are few but wide cracks, fragility destruction may take place in the structure 4, Pressed big and partial. Heavy to press and mix person who draw muscle a less one light to pigeonhole into the ponent while being partial while being partial, similar to receiving the curved ponent. 5, Pressed small and partial. Small to press and mix person who draw muscle a more one heavy to pigeonhole into the ponent while being partial while being partial, similar to the centre and pressed the ponent. 6, Cut. Press obliquly when the hoop muscle is too dense and destroy, the oblique crack which is greater than 45?? direction appears along the belly of roof beam end。 Structure rigidity is insufficient。s best, this text make an more overall analysis , summary to concrete kind and reason of production , bridge of crack as much as possible, in order to design , construct and find out the feasible method which control the crack , get the result of taking precautions against Yu WeiRan. Concrete bridge crack kind, origin cause of formation In fact, the origin cause of formation of the concrete structure crack is plicated and various, even many kinds of factors influence each other , but every crack has its one or several kinds of main reasons produced . The kind of the concrete bridge crack, on its reason to produce, can roughly divide several kinds as follows : (1) load the crack caused Concrete in routine quiet . Is it load to move and crack that produce claim to load the crack under the times of stress bridge, summing up has direct stress cracks , two kinds stress crack onces mainly. Direct stress crack refer to outside load direct crack that stress produce that cause. The reason why the crack produces is as follows, 1, Design the stage of calculating , does not calculate or leaks and calculates partly while calculating in structure。 （八） 橋梁建成以后，原有地基條件變化。 （四） 結(jié)構(gòu)基礎(chǔ)類型差別大。 四、 地基礎(chǔ)變形引起的裂縫 由于基礎(chǔ)豎向不均勻沉降或水平方向位移，使結(jié)構(gòu)中產(chǎn)生附加應(yīng)力，超出混凝土結(jié)構(gòu)的抗拉能力，導(dǎo)致結(jié)構(gòu)開裂。 （六） 外界環(huán)境。 （三）水灰比。 混凝土收縮裂縫的特點(diǎn)是大部分屬表面裂縫，裂縫寬度較細(xì)，且縱橫交錯(cuò)，成龜裂狀，形狀沒有任何規(guī)律?；炷劣不笫湛s主要就是縮水收縮。發(fā)生在施工過程中、混凝土澆筑后 4~5小時(shí)左右，此時(shí)水泥水化反應(yīng)激烈，分子鏈逐漸形成，出現(xiàn)泌水和水分急劇蒸發(fā)，混凝土失水收縮，同時(shí)骨料因自重下沉，因此時(shí)混凝土尚未硬化，稱為塑性收縮。施工中應(yīng)根據(jù)實(shí)際情況，盡量選擇水化熱低的水泥品種，限制水泥單位用量，減少骨料入模溫度，降低內(nèi)外溫差，并緩慢降溫，必要時(shí)可采用循環(huán)冷卻系統(tǒng)進(jìn)行內(nèi)部散熱，或采用薄層連續(xù)澆筑以加快散熱。橋面板、主梁或橋墩側(cè)面受太陽曝曬后，溫度明顯高于其它部位，溫度梯度呈非線形分布。 二、 溫度變化引起 的裂縫 混凝土具有熱脹冷縮性質(zhì)，當(dāng)外部環(huán)境或結(jié)構(gòu)內(nèi)部溫度發(fā)生變化，混凝土將發(fā)生變形，若變形遭到約束，則在結(jié)構(gòu)內(nèi)將產(chǎn)生應(yīng)力，當(dāng)應(yīng)力超過混凝土抗拉強(qiáng)度時(shí)即產(chǎn)生溫度裂縫。 （六）受剪。 （三） 受彎。荷載裂縫特征依荷載不同而異呈現(xiàn)不同的特點(diǎn)。研究表明，受力構(gòu)件挖孔后，力流將產(chǎn)生繞射現(xiàn)象，在孔洞附近密集，產(chǎn)生巨大的應(yīng)力集中。裂縫產(chǎn)生的原因有： （一） 設(shè)計(jì)計(jì)算階段，結(jié)構(gòu)計(jì)算時(shí)不計(jì)算或部分漏算；計(jì)算模型不合理；結(jié)構(gòu)受力假設(shè)與實(shí)際受力不符；荷載少算或漏算；內(nèi)力與配筋計(jì)算錯(cuò)誤；結(jié)構(gòu)安全系數(shù)不夠。 科學(xué)技術(shù)學(xué)院 專業(yè) 外文資料 翻譯 題 目： 橋梁裂縫產(chǎn)生原因淺析 學(xué) 科 部： 理工學(xué)科部 專 業(yè)： 土木工程道橋方向 班 級： 土木 094 班 學(xué) 號： 7011509043 學(xué)生姓名： 熊中偉 指導(dǎo)教師： 吳友平 橋梁裂縫產(chǎn)生原因淺析 近年來，我省交通基礎(chǔ)建設(shè)得到迅猛發(fā)展，各地 建立了 大量的混凝土橋梁。直接應(yīng)力裂縫是指外荷載引起的直接應(yīng)力產(chǎn)生的裂縫。 （二） 橋梁結(jié)構(gòu)中經(jīng)常需要鑿槽、開洞、設(shè)置牛腿等，在常規(guī)計(jì)算中難以用準(zhǔn)確的圖式進(jìn)行模擬計(jì)算，一般根據(jù)經(jīng)驗(yàn)設(shè)置受力鋼筋。在設(shè)計(jì)上，應(yīng)注意避免結(jié)構(gòu)突變（或斷面突變），當(dāng)不能回避時(shí)，應(yīng)做局部處理，如轉(zhuǎn)角處做圓角，突變處做成漸變過渡，同時(shí)加強(qiáng)構(gòu)造配筋，轉(zhuǎn)角處增配斜向鋼筋，對于較大孔洞有條件時(shí)可在周邊設(shè)置護(hù)邊角鋼。沿構(gòu)件出現(xiàn)平行于受力方向的短而密的平行裂縫。小偏心受壓和受拉區(qū)配筋較多的大偏心受壓構(gòu)件，類似于中心受壓構(gòu)件。在局部受壓區(qū)出現(xiàn)與壓力方向大致平行的多條短裂縫。 （二） 日照。出現(xiàn)在施工過程中，大體積混凝土（厚度超過 ）澆筑之后由于水泥水化放熱，致使內(nèi)部溫度很高，內(nèi)外溫差太大，致使表面出現(xiàn)裂縫。 塑性收縮。因混凝土表層水分損失快，內(nèi)部損失慢，因此產(chǎn)生表面收縮大、內(nèi)部收縮小的不均勻收縮，表面收縮變形受到內(nèi)部混凝土的約束，致使表面混凝土承受拉力，當(dāng)表面混凝土承受拉力超過其抗拉強(qiáng)度時(shí)，便產(chǎn)生收縮裂縫。炭化收縮一般不做計(jì)算。另外骨料粒徑大收縮小，含水量大收縮越大。蒸汽養(yǎng)護(hù)方式比自然養(yǎng)護(hù)方式混凝土收縮要小。構(gòu)造上配筋宜優(yōu)先采用小直徑鋼筋 (φ 8~φ 14)、小間距布置 (10~15cm)，全截面構(gòu)造配筋率不宜低于 %，一般可采用 %~%。在地質(zhì)情況比較一致條件下，各部分基礎(chǔ)荷載差異太大時(shí)，有可能引起不均勻沉降，例如高填土箱形涵洞中部比兩邊的荷載要大，中部的沉降就要比兩邊大，箱涵可能開裂。 （七） 橋梁基礎(chǔ)置于滑坡體、溶洞或活動斷層等不良地質(zhì)時(shí)，可能造成不均勻沉降。 The bridge crack produced the reason to simply analyse In recent years, the traffic capital construction of our province gets swift and violent development, all parts have built a large number of concrete bridges. In the course of building and using in the bridge, relevant to influence project quality lead of mon occurrence report that bridge collapse even because the crack appears The concrete can be said to often have illness ing on while fracturing and frequentlyoccurring disease , often perplex bridge engineers and technicians. In fact , if take certain design and construction measure, a lot of cracks can be overe and controlled. For strengthen understanding of concrete bridge crack further, is it prevent project from endanger larger crack to try one39。 It is simply little and assigning the mistake for reinforcing bar to set up。 Strong wind , heavy snow , earthquake happen , explode etc.. Stress crack once means the stress of secondary caused by loading outside produces the crack. The reason why the crack produces is as follows, 1, In design outside load function , because actual working state and routine , structure of thing calculate have discrepancy or is it consider to calculate, thus cause stress once to cause the structure to fracture in some position. Two is it join bridge arch foot is it is it assign X shape reinforcing bar , cut down this place way , section of size design and cut with scissors at the same time to adopt often to design to cut with scissors, theory calculate place this can store curved square in , but reality should is it can resist curved still to cut with scissors, so that present the crack and cause the reinforcing bar corrosion. 2, Bridge structure is it dig trough , turn on hole , set up ox leg ,etc. to need often, difficult to use a accurate one diagrammatic to is it is it calculate to imitate to go on in calculating in routine, set up and receive the strength reinforcing bar in general foundation experience. Studi