【正文】 d concrete members only for some simple situations. Actually, the joint action of two materials as dissimilar and plicated as concrete and steel is so plex that it has not yet lent itself to purely analytical treatment. For this reason, methods of design and analysis, while using these assumptions, are very largely based on the results of extensive and continuing experimental research. They are modified and improved as additional test evidence bees available. 4 鋼筋混凝土的基本假設(shè) 作為結(jié)構(gòu)工程師的主要任務(wù)是結(jié)構(gòu)設(shè)計。設(shè)計是對一般的結(jié)構(gòu)和特定結(jié)構(gòu)等所有層面的一個具體的確定，使結(jié)構(gòu)可以被安全地建造，并安全地承受的各種因素的影響，在它的整個使用壽命中能夠很好的發(fā)揮作用。這些影響主要是來自承受的負載和其它受到的因 素，以及其他有害的影響如溫度波動，基礎(chǔ)下陷的影響或是受到侵蝕的影響。結(jié)構(gòu)力學(xué)是結(jié)構(gòu)設(shè)計的主要工具之一，在這個設(shè)計過程中，要做一個良好的預(yù)測，得到結(jié)構(gòu)變形的程度，能夠及時的采取一定的措施去加固。在這個過程中要做的最重要的事是：（ 1）充分的研究這個結(jié)構(gòu)，即能夠得到這個結(jié)構(gòu)所能承受的極限的結(jié)構(gòu)荷載的大小和強度（ 2）還有就是變形，了解結(jié)構(gòu)在承受荷載時變形的程度，出現(xiàn)裂縫的程度。 以上所提到的鋼筋混凝土的力學(xué)基礎(chǔ)的基本主張是： 內(nèi)部力量，如彎矩，剪力，承受正常剪應(yīng)力的任何一個結(jié)構(gòu)部分，在受外部負載的影響時部分的結(jié) 構(gòu)是平衡的。這一主張不是一個假設(shè)，而是一個事實，因為任何機構(gòu)或其任何部分在整個結(jié)構(gòu)中受力都是平衡的。 一個嵌入式鋼筋的應(yīng)變與外部具體是相同的。這是假設(shè)混凝土和鋼筋之間存在完美結(jié)合，這樣兩種材料之間沒有可能發(fā)生滑移。因此，一個構(gòu)件在變形時，機械的連鎖提供自然截面的附著力，所以是非常接近這個假設(shè)的。 在截面那些負載裝載之前，應(yīng)繼續(xù)在加載的負載。精確的測量表明，當(dāng)一個鋼筋混凝土構(gòu)件加載接近失敗時，這種假設(shè)并非絕對準確。但是，通常偏差是輕微的。 在鑒于混凝土的抗拉強度比起其抗壓強度差很多，在這一個構(gòu)件中 ，肯定會存在裂縫，雖然這些裂縫在精心設(shè)計的構(gòu)件中通常是難以見到。這種假設(shè)顯然是實際情況比較簡單，因為事實上，混凝土開裂之前，位于混凝土的裂縫處有抵制小幅度的拉應(yīng)力。后來在鋼筋混凝土梁的抗剪切的討論中，這種特定的假設(shè)有一定的條件和優(yōu)勢是明顯的，適當(dāng)配合比強度的混凝土可以有發(fā)展的前景的。 該理論是基于實際應(yīng)力應(yīng)變關(guān)系和兩部分組成材料合理的組 合產(chǎn)生的等效強度性能。理論的內(nèi)容在實際生活中體現(xiàn)，將這兩個材料聯(lián)合使用比那些高彈性材料建造的結(jié)構(gòu)的 結(jié)構(gòu)設(shè)計復(fù)雜得多也更具挑戰(zhàn)性。 這五個假 設(shè)能預(yù)測一些簡單的情況下鋼筋混凝 土構(gòu)件。事實上鋼筋和混凝土這兩個 中同樣復(fù)雜的材料，在一起使用時不適于純粹的分析處理。由于這個原因，在結(jié)構(gòu)的設(shè)計方法和分析使用這些假設(shè)時，最主要的依據(jù)是廣泛和持續(xù)使用的實驗研究結(jié)果，這些修改和補充檢驗的理論可以使鋼筋混凝土結(jié)構(gòu)變得可以 被 使用。 5 Development Tendency and Instructions of Civil Engineering With the progress in science and technology and engineering development of the practice of the disciplines of Civil Engineering has developed into a broad connotation, many categories, and the structure of plex integrated system. For example, on civil engineering projects built with the use of facilities in terms of functionality, and some interest for residential purposes； Some production activities。 some for land, sea and air transport。 some for water utilities。 some as a tool for information transmission。 some as a means of energy transmission and so on. This requires the integrated use of a variety of civil engineering material conditions in order to meet diverse needs. Civil Engineering has developed a lot of branches, such as housing projects, railway projects, road projects, airport projects, bridge projects, the tunnel and underground engineering, special engineering structures, water supply and drainage works, urban heating for the gas works, port works, water conservancy engineering sciences. Some of these branches, such as water conservancy project, because of their own projects targeted at the growing and specialized scientific and technological development have been divided out from the civil engineering disciplines as an independent system, but they are still largely in mon with civil engineering. Civil Sociality are acpanied by the development of human society developed. It reflects the construction of engineering facilities in every historical period of socioeconomic, cultural, scientific, technical development of the face, thus civil society has bee one of the historical development of the witness. Ancient times, people will start to build simple houses, roads, bridges to meet the needs of easy living and production needs. Later, the people in order to adapt to the war, production and dissemination of religious life and the needs of the construction of the city, canals, palaces, temples and other buildings. Many wellknown works shown in this historical period of human creativity. For example, China39。s Great Wall, Du Jiang Yan, the Grand Canal, Zhao Zhou Bridge, Ying Xian Wooden Tower, Egypt39。s pyramids, the Greek Parthenon, Rome39。s water supply engineering, coliseum amphitheater (Rome large bucket beast field), as well as many other wellknown churches, palaces and so on. After the industrial revolution, especially to the 20th century, on the one hand, civil society to put forwards a new demand。 on the other hand, are all areas of society 6 for the advancement of Civil Engineering has created favorable conditions. Such as building materials (steel, cement) implementation of industrial production, machinery and ene