【正文】 St. Louis (18671874), in which tubular steel ribs were used to form arches with a span of more than 500ft (). In Britain, the Firth of Forth cantilever bridge (188390) employed tubular struts, some 12 ft () in diameter and 350 ft (107m) long. Such bridges and other structures were important in leading to the development and enforcement of standards and codification of permissible design stresses. The lack of adequate theoretical knowledge, and even of an adequate basis for theoretical studies, limited the value of stress analysis during the early years of the 20th century, as occasionally failures, such as that of a cantilever bridge in Quebec in 1907, failures were rare in the metalskeleton office buildings。 and in 1849 the first I beams, feet () long , were fabricated as roof girders for a Paris railroad station. Two years later Joseph Paxton of England built the Crystal Palace for the London Exposition of 1851. He is said to have conceived the idea of cage constructionusing relatively slender iron beams as a skeleton for the glass walls of a large, open structure. Resistance to wind forces in the Crystal palace was provided by diagonal iron rods. Two feature are particularly important in the history of metal construction。Merril in which an exterior closely spaced framed tube in concrete envelops an interior steel framing, thereby bining the advantages of both reinforced concrete and structural steel systems. The 52story One Shell Square Building in New Orleans is based on this system. Steel construction refers to a broad range of building construction in which steel plays the leading role. Most steel construction consists of largescale buildings or engineering works, with the steel generally in the form of beams, girders, bars, plates, and other members shaped through the hotrolled process. Despite the increased use of other materials, steel construction remained a major outlet for the steel industries of the , , , Japan, West German, France, and other steel producers in the 1970s. Early history. The history of steel construction begins paradoxically several decades before the introduction of the Bessemer and the SiemensMartin (openhearth) processes made it possible to produce steel in quantities sufficient for structure use. Many of problems of steel construction were studied earlier in connection with iron construction, which began with the Coalbrookdale Bridge, built in cast iron over the Severn River in England in 1777. This and subsequent iron bridge work, in addition to the construction of steam boilers and iron ship hulls , spurred the development of techniques for fabricating, designing, and joining. The advantages of iron over masonry lay in the much smaller amounts of material required. The truss form, based on the resistance of the triangle to deformation, long used in timber, was translated effectively into iron, with cast iron being used for pression ., those bearing the weight of direct loadingand wrought iron being used for tension ., those bearing the pull of suspended loading. The technique for passing iron, heated to the plastic state, between rolls to form flat and rounded bars, was developed as early as 1800。ade of the building as a structural element which acts with the framed tube, thus providing an efficient way of resisting lateral loads in highrise buildings, and resulting in costeffective columnfree interior space with a high ratio of to gross floor area. Because of the contribution of the stressedskin fa231。計(jì)算機(jī)在工程上的運(yùn)用代替了冗長(zhǎng)的手工計(jì)算，從而更加促進(jìn) 了鋼結(jié)構(gòu)的發(fā)展，并大大的減低了造價(jià)。 二戰(zhàn)結(jié)束后，歐洲，美國(guó)，日本等國(guó)都擴(kuò)大了對(duì)在不定應(yīng)力（包括超過(guò)屈服點(diǎn)的情況）作用下各種結(jié)構(gòu)鋼的性質(zhì)的研究，并進(jìn)行了更為精確、系統(tǒng)的分析。但直到第二次世界大戰(zhàn)后才用于建筑結(jié)構(gòu)中。但是與此同時(shí)，焊接代替了鉚釘連接則是一個(gè)很重要的發(fā)展。先是螺栓連接緊接著鉚釘連接，最后是裝修，整個(gè)工程的最終完成只用了一年零 45 天。由九架起重機(jī)將這些梁提升到指定的位置。 次項(xiàng)工程所需要的梁是由 Bayonne 海灣對(duì)岸的軍械庫(kù)所提供的。 102 層高 1250 英尺（ 381 米）的帝國(guó)大廈在后來(lái)的 40 年一直保持著世界最高的地位。 第一次世界大戰(zhàn)暫時(shí)中斷了所謂摩天大廈（當(dāng)時(shí)這個(gè)詞并沒(méi)有確定）的蓬勃發(fā)展，但是二十世紀(jì)二十年代又恢復(fù)了這一趨勢(shì)。芝加哥的 John Hancock 中心就是一個(gè)很顯著的例子。而只有考慮到具體的單獨(dú)梁與單獨(dú)柱的抗彎能力以及梁柱相交處的剛度的框架設(shè)計(jì)才是可靠的。為了控制道路的阻塞，要對(duì)建筑的縮進(jìn)設(shè)計(jì)進(jìn)行限定。 1908年在華爾街建造的高 468 英尺（ 143 米）的城市投資公司大廈，高 612 英尺（ 187 米）的星爾大廈，以及 700 英尺（ 214 米）的都市塔和 780 英尺高（ 232 米）的 Woll worth大廈。 1902年在紐約建造的高 286英寸（ 米）的 Flatiron 大廈不斷地被后來(lái)的建筑所超越。 緊隨著鋼結(jié)構(gòu)的發(fā)展， 1988 年第一部電梯問(wèn)世了。 1885 年最重的型鋼通過(guò)熱軋生產(chǎn)出來(lái)，每英寸不到 100 磅（ 45 千克）。 盡管幾十年來(lái)之中建筑形式主要是在美國(guó)發(fā)展的，但是它卻影響著全世界鋼材工業(yè)的發(fā)展。有時(shí)為了抵抗風(fēng)荷載還是在豎向構(gòu)件和橫向構(gòu)件的連接點(diǎn)出貼覆上節(jié)點(diǎn)板來(lái)加固結(jié)構(gòu)。鋼材在這些結(jié)構(gòu)中起了非常大的作用。實(shí)心砌體 的天井與界墻提供抵抗風(fēng)載的側(cè)向支撐。大廈的梁是鋼制的，而柱是鑄鐵所制。18841885 年，芝加哥的工程師 Le Baron Jennny 設(shè)計(jì)了家庭保險(xiǎn)公司大廈。無(wú)論是它的高度（比著名的金字塔的兩倍還高），架設(shè)的速度 人數(shù)不多的工作人