晉城市澤州縣玉川橋結(jié)構(gòu)設(shè)計-資料下載頁
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【正文】 ntury . Prestressed concrete was first used in 1927.Stone bridges of the arch type (integrated superstructure and substructure) were constructed in Rome and other European cities in the middle ages . These arches were halfcircular , with flat arches beginning to dominate bridge work during the Renaissance period. This concept was markedly improved at the end of the eighteenth century and found structurally adequate to acmodate future railroad loads . In terms of analysis and use of materials , stone bridges have not changed much ,but the theoretical treatment was improved by introducing the pressureline concept in the early 1670s(Lahire, 1695) . The arch theory was documented in model tests where typical failure modes were considered (Frezier,1739).Culmann(1851) introduced the elastic center method for fixedend arches, and showed that three redundant parameters can be found by the use of three equations of coMPatibility.Wooden trusses were used in bridges during the sixteenth century when Palladio built triangular frames for bridge spans 10 feet long . This effort also focused on the three basic principles og bridge design : convenience(serviceability) ,appearance , and endurance(strength) . several timber truss bridges were constructed in western Europe beginning in the 1750s with spans up to 200 feet (61m) supported on stone substructures .Significant progress was possible in the United States and Russia during the nineteenth century ,prompted by the need to cross major rivers and by an abundance of suitable timber . Favorable economic considerations included initial low cost and fast construction .The transition from wooden bridges to steel types probably did not begin until about 1840 ,although the first documented use of iron in bridges was the chain bridge built in 1734 across the Oder River in Prussia . The first truss pletely made of iron was in 1840 in the United States , followed by England in 1845 , Germany in 1853 , and Russia in 1857 . In 1840 , the first iron arch truss bridge was built across the Erie Canal at Utica . The Impetus of Analysis The theory of structures ,developed mainly in the ninetheenth century,focused on truss analysis, with the first book on bridges written in 1811. The Warren triangular truss was introduced in 1846 , supplemented by a method for calculating the correcet forces .Ibeams fabricated from plates became popular in England and were used in shortspan bridges.In 1866, Culmann explained the principles of cantilever truss bridges, and one year later the first cantilever bridge was built across the Main River in Hassfurt, Germany, with a center span of 425 feet (130m) . The first cantilever bridge in the United States was built in 1875 across the Kentucky most impressive railway cantilever bridge in the nineteenth century was the First of Forth bridge , built between 1883 and 1893 , with span magnitudes of 1711 feet (). 橋梁工程的發(fā)展概況早在公元前1世紀(jì)，Marcus Vitrucios Pollio 的著作中就有關(guān)于建筑材料和結(jié)構(gòu)類型的記載和評述。后來古希臘人創(chuàng)立了靜力學(xué)的基本原理， Leonardo da Vinci 、Cardeno和Galileo 等人在工作和應(yīng)用中也證實(shí)了這些原理的正確性。而在15世紀(jì)至16世紀(jì)期間，工程師們似乎并沒有注意到這些文字記載，只是單憑經(jīng)驗(yàn)和傳統(tǒng)來建造橋梁和渡槽。到了17世紀(jì)末， 隨著Leibnitz、Newton 和Bernoulli的數(shù)學(xué)理論的創(chuàng)立，橋梁建筑技術(shù)得到了快速發(fā)展。Lahire (1695)和belidor（1729）出版的關(guān)于結(jié)構(gòu)理論分析的著作為材料力學(xué)領(lǐng)域奠定了基礎(chǔ)。Kuzmanovic （1977）指出，石材和木材是橋梁建筑最早采用的材料。在從木材到鋼材的轉(zhuǎn)變過程中，鐵作為一種過渡材料被用于橋梁建筑中。根據(jù)近期的記載。早在1840年，法國就在Grisoles 建造了一座跨度為39英尺（12米）的橫跨 Garoyne 運(yùn)河的混凝土橋梁， 但鋼筋混凝土橋直到本世紀(jì)初才出現(xiàn)，而預(yù)應(yīng)力混凝土到1927年才開始使用。早在中世紀(jì)，羅馬和歐洲的其他一些城市開始建造集上下部結(jié)構(gòu)于一體的半圓弧石拱橋，而文藝復(fù)興時期則是坦拱逐漸占主導(dǎo)地位。這種觀念在18世紀(jì)末有了明顯的改進(jìn)，并發(fā)現(xiàn)其在結(jié)構(gòu)上能適應(yīng)后來的鐵路荷載。在材料的分析和使用上，石拱橋至今沒有發(fā)生大的變化，但是由于在17世紀(jì)70年代初期（Lahire,1965）引進(jìn)了壓力線的概念，使得拱橋的理論分析得到了改進(jìn)。通過模型試驗(yàn)，有關(guān)拱結(jié)構(gòu)的主要失效形式的理論得到了證實(shí)（Frezier ,1739）。對于無鉸拱，Culmann (1851 ) 引進(jìn)了彈性中心的方法，顯示了可用三個協(xié)調(diào)方程求解三個多余參數(shù)。當(dāng)palladio建造了一座跨度為10英尺的三角形木制框架橋后，16世紀(jì)開始，木桁架在橋梁中得到應(yīng)用。這些設(shè)計同樣遵循橋梁設(shè)計的三個基本原則：方便（實(shí)用性）、美觀和耐久性（強(qiáng)度）。18世紀(jì)50年代西歐建造了若干座支承于石制橋墩上的木桁架橋，其跨度達(dá)到200英尺（61米）。19世紀(jì)期間，美國和俄羅斯由于其跨越主要河流的需要，而且兩國都具有豐富的適用于建橋的木材資源，因此木制橋梁在美、俄兩國有可能取得更為顯著的成績。木制橋梁具有良好的經(jīng)濟(jì)性，因?yàn)槠涑跗谕顿Y較低，施工速度較快。盡管有文獻(xiàn)記載，早在1734年，在普魯士就修建了第一座橫跨Oder河的鐵鏈橋，但從木橋到鋼橋的過渡大概開始于1840年。美國于1840年建成了第一座全鐵桁架橋，其后，英格蘭、德國和俄羅斯分別于1845年、1853年和1857年也建成了鐵桁架橋。1840年，第一座鐵桁架拱橋出現(xiàn)在Utica的Erie運(yùn)河上。理論分析的推動作用 主要從19世紀(jì)發(fā)展起來的機(jī)構(gòu)分析理論著重于桁架的分析，首部關(guān)于橋梁工程的著作于1811年出版。1846年出現(xiàn)了一種Warren 三角形桁架和計算這種桁架精確內(nèi)力的分析方法。用板件組合而成的工字形梁在英國逐漸普及并在小跨度橋梁中得到應(yīng)用。1866年Culmann闡述了懸臂桁架橋的原理，一年后在德國的Hassfurt的Main 河上就建造了首座主跨跨度達(dá)425英尺（130米）的懸臂梁橋。美國的首座懸臂梁橋于1875年建于Kentucky河上。19世紀(jì)最引人注目的鐵路懸臂梁橋要數(shù)Firth of Forth橋，此橋建于1883年至1890年間，跨度達(dá)1，711英尺（）大約就在這一時期，結(jié)構(gòu)鋼在橋梁工程中作為一種主要材料被推廣應(yīng)用，盡管此時鋼材的性能大都較差。幾個早期的工程實(shí)例是：（1） 橋；（2）New York的Brooklyn 橋；（3）Missouri 的 Glasgow 大橋，這些橋都建于1874年至1883年間。65
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