【五層】7144平米局部三層技工實驗樓（計算書、部分建筑結(jié)構(gòu)圖）

【五層】7144平米局部三層技工實驗樓（計算書、部分建筑結(jié)構(gòu)圖）,【溫馨提示】壓縮包內(nèi)含CAD圖有預(yù)覽點開可看。打包內(nèi)容里dwg后綴的文件為CAD圖,可編輯,無水印,高清圖,壓縮包內(nèi)文檔可直接點開預(yù)覽,需要原稿請自助充值下載,所見才能所得,請細心查看有疑問可以咨詢QQ：11970985或197216396 浙江工業(yè)大學(xué)畢業(yè)設(shè)計 某技工學(xué)校2#實驗樓 浙江工業(yè)大學(xué)建筑工程學(xué)院 畢業(yè)設(shè)計外文資料翻譯 學(xué)生姓名： 紀(jì)朋輝 學(xué) 號：200404160310 專業(yè)： 土木工程 　 外文翻譯內(nèi)容： 預(yù)應(yīng)力混凝土 外文出處： 專業(yè)課外閱讀材料 　　　 指導(dǎo)教師： 黃亮 陳惟 　 附件：外文原文　 　　 2008年3月1日 預(yù)應(yīng)力混凝土 混凝土的力學(xué)特性是抗壓不抗拉：它的抗拉強度是抗壓強度的8%-14%?；炷恋目估瓘姸热绱说?，因此在加荷載的初期階段就產(chǎn)生彎曲裂縫。為了減少或防止這種裂縫的發(fā)展，所以在結(jié)構(gòu)單元縱向施加了一個中心或偏心的軸向力。這個力的施加消除或大大減少了工作荷載下結(jié)構(gòu)中最危險的跨中和支柱截面處的拉應(yīng)力，阻止了裂縫的發(fā)展，也因此提高了截面的抗彎、抗剪和抗扭能力。這樣，構(gòu)件能表現(xiàn)出彈性性質(zhì)，當(dāng)全部荷載作用于結(jié)構(gòu)時，混凝土構(gòu)件的全部斷面的抗壓能力都能夠被充分有效的發(fā)揮出來。 這個強加于構(gòu)件的縱向力就叫做預(yù)應(yīng)力，就是在構(gòu)件承受橫向的重力恒載和活載或水平向的瞬時活載之前，沿著結(jié)構(gòu)單元跨度方向預(yù)先給截面施加一個壓縮力。預(yù)應(yīng)力的類型及大小主要是根據(jù)要建造的系統(tǒng)類型、跨長和構(gòu)件細長度的需要來決定。由于預(yù)應(yīng)力是沿著或平行于構(gòu)件的軸向縱向施加的，因此這種施加預(yù)應(yīng)力的原理一般被稱作直線預(yù)應(yīng)力法。 環(huán)形預(yù)應(yīng)力法應(yīng)用于建造盛放流體的構(gòu)筑物中，如儲水池、管道和壓力反應(yīng)堆容器等，它本質(zhì)上和直線預(yù)應(yīng)力的基本原理相同。這種柱形或球形結(jié)構(gòu)的環(huán)向箍力或圍壓就抵消了由內(nèi)部壓力在結(jié)構(gòu)外表面一起的環(huán)形拉應(yīng)力。 Fig.1.2.1prestressing principle in linear and circular prestressing 如圖1.2.1用基本模型描述了在兩種結(jié)構(gòu)系統(tǒng)類型上的預(yù)應(yīng)力作用及應(yīng)力反應(yīng)結(jié)果。圖（a）是在大的預(yù)壓應(yīng)力P下單個的混凝土塊組成的梁模型。雖然它可能出現(xiàn)混凝土塊間的滑動或在豎向模擬剪切滑動破壞，但實際上由于縱向壓力P存在這種情況是不會發(fā)生的。同樣，圖（c）所示木制木桶的木板似乎會由于施加在其上面的內(nèi)部的徑向高壓力而分開，但是同上面情況一樣，由于金屬箍預(yù)先施加的力在木桶外周形成一種環(huán)向的預(yù)壓應(yīng)力，使木板紋絲不動。 從前面的討論中可以清楚的看出，為了消除或大大減少荷載在預(yù)應(yīng)力結(jié)構(gòu)單元上引起的純拉應(yīng)力，在他們承受整個的恒載和活荷載前，就預(yù)先給他們施加一個永久的預(yù)壓應(yīng)力。在一般的鋼筋混凝土結(jié)構(gòu)中，通常認為混凝土的抗拉強度使可以不加考慮、忽略不計的，這是因為彎矩產(chǎn)生的拉應(yīng)力由加筋處理后的黏合層來抵抗。也因此，鋼筋混凝土結(jié)構(gòu)在工作荷載下達到極限狀態(tài)后產(chǎn)生的裂紋和撓曲變形不可恢復(fù)。 和預(yù)應(yīng)力鋼筋的作用相反、普通鋼筋混凝土構(gòu)件中的鋼筋不給構(gòu)件施加任何力。在預(yù)應(yīng)力構(gòu)件中，鋼筋要通過預(yù)應(yīng)力作用給構(gòu)件主動施加預(yù)載，使構(gòu)件對裂縫和變形有相對較高的恢復(fù)控制能力，一旦預(yù)應(yīng)力構(gòu)件受力使混凝土超過了其彎曲抗拉強度，則構(gòu)件開始表現(xiàn)出鋼筋混凝土構(gòu)件的性質(zhì)。 在同等跨度和受荷載條件下，預(yù)應(yīng)力構(gòu)件要比一般的鋼筋混凝土構(gòu)件要薄。一般來說，預(yù)應(yīng)力混凝土構(gòu)件的厚度通常約是同等鋼筋混凝土構(gòu)件厚度的65%—80%。因此，預(yù)應(yīng)力構(gòu)件需要的混凝土量要少，約占鋼筋混凝土構(gòu)件需要用量的20%—35。不行的是，在材料重量方面節(jié)省的花費和在預(yù)應(yīng)力措施中需要的較高質(zhì)量材料的較高費用剛好抵消掉了。同時，不管什么樣的結(jié)構(gòu)體系，預(yù)應(yīng)力方法本身就造成附加的費用：模板更加復(fù)雜，因為預(yù)加應(yīng)力的截面的集合形狀通常由帶薄腹板的翼形面組成。 盡管有這些附加的費用，通常情況下，如果產(chǎn)生的預(yù)制構(gòu)件在數(shù)量上足夠的話，預(yù)應(yīng)力構(gòu)件和鋼筋混凝土構(gòu)件相比，至少最初直接成本的差異不是太大，但因為預(yù)應(yīng)力構(gòu)件不需要太多的維護，因為混凝土質(zhì)量好，它的實用壽命長，而且由于上部結(jié)構(gòu)的累積荷載重量較小，基礎(chǔ)重量也相應(yīng)輕得多，所以從長期來看，間接費用的節(jié)約還是很巨大的。 一旦鋼筋混凝土梁跨度超過70到90尺（21.3到27.4米），這樣大的梁自重就變得過大。結(jié)構(gòu)，構(gòu)件較重，造成長期的比較大的變形和裂縫。這樣一來，對大跨度結(jié)構(gòu)，預(yù)應(yīng)力混凝土就顯得格外必要了，因為大跨度結(jié)構(gòu)用拱形建造的成本很高，而且也不能消除鋼筋混凝土拱長期實用下嚴重的收縮和徐變，像分段拼裝式橋或斜拉橋這些跨度很大的建筑物只能利用預(yù)應(yīng)力構(gòu)件建造。 預(yù)應(yīng)力混凝土不是一個新事物，可追溯到1872年，當(dāng)時來自加州的一個工程師P.H. 杰克深申請了一項預(yù)應(yīng)力系統(tǒng)的專利，他用拉桿把單個的塊體建造成了梁或拱【圖1.2.1（a）】。由于在克服預(yù)應(yīng)力損失方面高強度鋼筋沒有效果，在很長一段時間預(yù)應(yīng)力研究進展很小，亞歷山大的R. E. Dill和Nebraska揭示了混凝土的收縮和徐變（材料橫向流變）對預(yù)應(yīng)力損失的影響。他后來提出了連續(xù)的自由拉桿后張法，這一方法彌補了由混凝土隨時間發(fā)展的徐變和收縮導(dǎo)致構(gòu)件長度減小而引起的拉桿中的預(yù)應(yīng)力損失。在20世紀(jì)20年代早期，美國明尼阿波利斯州的W. H. Hewett發(fā)展了環(huán)向預(yù)應(yīng)力原理。他在混凝土容器壁通過螺絲扣給水平向鋼筋施加環(huán)向應(yīng)力，防止其在內(nèi)部壓力下產(chǎn)生裂縫，也借此達到了不滲水。從那以后，容器和管道中預(yù)應(yīng)力的實用在美國飛速發(fā)展，成千上萬的儲水、液體或氣體的容器被建成，緊接著在二三十年內(nèi)建造了無數(shù)英里的預(yù)應(yīng)力管道。 直線預(yù)應(yīng)力法在歐洲和法國繼續(xù)得到了進一步發(fā)展，值得一提的是尤金·布雷西奈的創(chuàng)新成果，他于1926—1928年間提出了高強度和高延性鋼的實用，能克服預(yù)應(yīng)力損失。在1940年，他提出了現(xiàn)在眾所周知并被普遍認可的弗雷西奈預(yù)應(yīng)力法。 英國的P. W. Abeles在20世紀(jì)30年代和60年代之間提出并發(fā)展了局部預(yù)應(yīng)力法的觀點。德國的F. Leonbardt、前蘇聯(lián)的V. Mikhailov和美國的T.Y.Lin也對預(yù)應(yīng)力混凝土的設(shè)計藝術(shù)和科學(xué)做了大量貢獻。Lin的負載平衡方法在這里應(yīng)該特別值得一提，因為它使設(shè)計過程大大簡化，尤其是對連接結(jié)構(gòu)而言。這些20世紀(jì)的發(fā)展成果已經(jīng)使得預(yù)應(yīng)力法在全世界廣泛實用，尤其以美國為甚。 今天，預(yù)應(yīng)力混凝土被用于建筑物、地下結(jié)構(gòu)、電視塔、浮動儲藏器和海上結(jié)構(gòu)、電站、核反應(yīng)堆容器和包括拱形橋和斜拉橋在內(nèi)的各種橋梁系統(tǒng)中，這些說明了預(yù)應(yīng)力概念的多方面多功能適應(yīng)性以及對它的廣泛應(yīng)用。所有這些結(jié)構(gòu)的發(fā)展和建造的成功都是由于材料技術(shù)進步所獲得的巨大收獲，特別是預(yù)應(yīng)力鋼和在估計預(yù)應(yīng)力長期和短期損失方面累積的知識。 原文 Prestressed Concrete Concrete is strong in compression, but weak in tension: Its tensile strength varies from 8 to 14 percent of its compressive strength. Due to such a low tensile capacity, flexural cracks develop at early stages of loading. In order to reduce or prevent such cracks from developing, a concentric or eccentric force is imposed in the longitudinal direction of the structural element. This force prevents the cracks from developing by eliminating or considerably reducing the tensile stresses at the critical midspan and support sections at service load, thereby raising the bending, shear, and torsional capacities of the sections. The sections are then able to behave elastically, and almost the full capacity of the concrete in compression can be efficiently utilized across the entire depth of the concrete sections when all loads act on the structure. Such an imposed longitudinal force is called a prestressing force, i.e., a compressive force that prestresses the sections along the span of the structural element prior to the application of the transverse gravity dead and live loads or transient horizontal live loads. The type of prestressing force involved, together with its magnitude, are determined mainly on the basis of the type of system to be constructed and the span length and slenderness desired. Since the prestressing force is applied longitudinally along or parallel to the axis of the member, the prestressing principle involved is commonly known as linear prestressing. Circular prestressing, used in liquid containment tanks, pipes, and pressure reactor vessels, essentially follows the same basic principles as does linear prestressing. The circumferential hoop, or “hugging” stress on the cylindrical or spherical structure, neutranzes the tensile stresses at the outer fibers of curvilinear surface caused by the internal contained pressure. Fig.1.2.1 prestressing principle in linear and circular prestressing Figure 1.2.1 illustrates, in a basic fashion, the prestressing action in both types of structural systems and the resulting stress response. In (a), the individual concrete blocks act together as a been due to the large compressive prestressing force P. Although it might appear that the blocks will slip and vertically simulate shear slip failure, in fact they will not because of the longitudinal force P. Similarly, the wooden staves in (c) might appear to be capable of separating as a result of the high internal radial pressure exerted on them. But again, because of the compressive prestress imposed by the metal bands as a form of circular prestressing, they will remain in place. From the preceding discussion, it is plain that permanent stresses in the prestressed structural member are created before the full dead and live loads are applied in order to eliminate or considerably reduce the net tensile stresses caused by these loads. With reinforced concrete, it is assumed that the tensile strength of the concrete is negligible and disregarded. This is because the tensile forces resulting from the bending moments are resisted by the bond created in the reinforcement process. Cracking and deflection are therefore essentially irrecoverable in reinforced concrete once the member has its limit state at service load. The reinforcement in the reinforced concrete member does not exert any force of its own on the member, contrary to the action of prestressing steel. The steel required to produce the prestressing force in the prestressed member actively preloads the member, permitting a relatively high controlled recovery of cracking and deflection. Once the flexural tensile strength of the concrete is exceeded, the prestressed member starts to act like a reinforced concrete element. Prestressed members are shallower in depth than their reinforced concrete counterparts for the same span and loading conditions. In general, the depth of a prestressed concrete member is usually about 65 to 80 percent of the depth of the equivalent reinforced concrete member. Hence, the prestressed member requires less concrete, and about 20 to 35 percent of the amount of reinforcement. Unfortunately this saving in material weight is balanced by the higher cost of the higher quality materials needed in prestressing. Also, regardless of the system used, prestressing operations themselves result in an added cost: Formwork is more complex, since the geometry of prestressed sections is usually composed of flanged sections with thin-webs. In spite of these additional costs, if a large enough number of precast units are manufactured, the difference between at least the initial costs of prestressed and reinforced concrete systems is usually not very large. And the indirect long-term savings are quite substantial, because less maintenance is needed: a longer working life is possible due to better quality control of the concrete, and lighter foundations are achieved due to the smaller cumulative weight of the superstructure. Once the beam span of reinforced concrete exceeds 70 to 90 feet (21.3 to 27.4m), the dead weight of the beam becomes excessive, resulting in heavier members and, consequently, greater long-term deflection and cracking. Thus, for larger spans, prestressed concrete becomes mandatory since arches are expensive to construct and do not perform as well due to the severe long-term shrinkage and creep they undergo. Very large spans such as segmental bridges or cable-stayed bridges can only be constructed through the use of pristressing. Prestressd concrete is not a new concept, dating back to 1872, when P.H.Jackson, an engineer from California, patented a prestressing system that used a tie rod to construct beams or arches from individual blocks [see Figure 1.2.1(a)]. After a long lapse of time during which little progress was made because of the unavailability of high-strength steel to overcome prestress losses,R.E.Dill of Alexandriak, Nebraska, recognized the effect of the shrinkage and creep (transverse material flow) of concrete on the loss of prestress. He subsequently developed the idea that successive post-tensioning of unbonded rods would compensate for the time-dependent loss of stress in the rods due to the decrease in the length of the member because of creep and shrinkage. In the early 1920s, W. H. Hewett of Minneapolis developed the principles of circular prestressing. He hoop-stressed horizontal reinforcement around walls of concrete tanks through the use of turnbuckles to prevent cracking due to internal liquid pressure, thereby achieving watertightness. Thereafter, prestressing of tanks and pipes develop at an accelerated pace in the United States, with thousands of tanks for water, liquid, and gas storage built and much mileage of prestressed pressure pipe laid in the two to three decades that followed. Linear prestressing continued to develop in Europe and in France, in particular through the ingenuity of Eugene Freyssinet , who proposed in 1925-1928 methods to overcome prestress losses through the use of high-strength and high-ductility steels. In 1940, he introduce the now well-know and well-accepted Freyssinet system. P.W. Abeles of England introduced and developed the concrpt of partial pretressing between the 1930s and 1960s. F. Leonhardt of Germany,V. Mikhailov of Russia, and T. Y. Lin of the United States also contributed a great deal to the art and science of the design of prestressed concrete. Lin’s load-balancing method deserves particular mention in this regard, as it considerably simplified the design process, particularly in continuous structures. These twentieth-century developments have led to the extensive use of prestressing throughout the world, and in the United States in particular. Today, prestressed concrete is used in buildings, underground structures, TV towers, floating storage and offshore structures, power stations, nuclear reactor vessels, and numerous types of bridge systems including segmental and cable-stayed bridges, they demonstrate the versatility of the prestressing concept and its all-encompassing application. The success in the development and construction of all these structures been due in no small measures to the advances in the technology of materials, particularly prestressing steel, and the accumulated knowledge in estimating the short-and long-term losses in the prestressing forces. 98