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1、<p>  2.1 Reinforced Concrete</p><p>  Plain concrete is formed from a hardened mixture of cement ,water ,fine aggregate, coarse aggregate (crushed stone or gravel),air, and often other admixtures. The

2、 plastic mix is placed and consolidated in the formwork, then cured to facilitate the acceleration of the chemical hydration reaction If the cement/water mix, resulting in hardened concrete. The finished product has high

3、 compressive strength, and low resistance to tension, such that its tensile strength is approximately one tenth If it</p><p>  It is this deviation in the composition of a reinforces concrete section from th

4、e homogeneity of standard wood or steel sections that requires a modified approach to the basic principles of structural design. The two components of the heterogeneous reinforced concrete section are to be so arranged a

5、nd proportioned that optimal use is made of the materials involved. This is possible because concrete can easily be given any desired shape by placing and compacting the wet mixture of the constituent</p><p>

6、;  The techniques necessary for placing concrete depend on the type of member to be cast ,that is, whether it is a column, a beams, a wall, a slab, a foundation. a mass columns, or an extension of previously placed and h

7、ardened concrete. For beams, columns, and walls, the forms should be well oiled after cleaning them, and the reinforcement should be cleared of rust and other harmful materials. In foundations, the earth should be compac

8、ted and thoroughly moistened to about 6 in. in depth to avoid a</p><p>  Hydration of the cement takes place in the presence of moisture at temperatures above 50°F. It is necessary to maintain such a co

9、ndition in order that the chemical hydration reaction can take place. If drying is too rapid, surface cracking takes place. This would result in reduction of concrete strength due to cracking as well as the failure to at

10、tain full chemical hydration.</p><p>  It is clear that a large number of parameters have to be dealt with in proportioning a reinforced concrete element, such as geometrical width, depth, area of reinforcem

11、ent, steel strain, concrete strain, steel stress, and so on. Consequently, trial and adjustment is necessary in the choice of concrete sections, with assumptions based on conditions at site, availability of the constitue

12、nt materials, particular demands of the owners, architectural and headroom requirements, the applicable codes, a</p><p>  A trial section has to be chosen for each critical location in a structural system. T

13、he trial section has to be analyzed to determine if its nominal resisting strength is adequate to carry the applied factored load. Since more than one trial is often necessary to arrive at the required section the first

14、design input step generates into a series of trial and adjustment analyses.</p><p>  The trial and adjustment procedures for the choice of a concrete section lead to the convergence of analysis and design. H

15、ence every design is an analysis once a trial section is chosen. The availability of handbooks, charts, and personal computers and programs supports this approach as a more efficient, compact, and speedy instructional me

16、thod compared with the traditional approach of treating the analysis of reinforced concrete separately from pure design.</p><p><b>  鋼筋混凝土</b></p><p>  普通混凝土是由水泥,水,細(xì)骨料,粗骨料(碎石或礫石),空氣和

17、其他一些經(jīng)常用的外加劑等混合物構(gòu)成。將混凝土放置在塑料模版內(nèi)進(jìn)行鞏固,加速水化反應(yīng),使混凝土盡快硬化?;炷恋某善酚休^高的抗壓強(qiáng)度,低導(dǎo)電性,它的抗拉強(qiáng)度約是抗壓強(qiáng)度的十分之一。因此,在混凝土拉伸的時(shí)候,拉伸和剪應(yīng)力加固在抗拉地區(qū)部分分配給補(bǔ)償脆弱的地區(qū)。</p><p>  正是因?yàn)檫@種偏差的存在,為了增強(qiáng)混凝土的抗壓承載能力,我們根據(jù)實(shí)際需要對(duì)不同標(biāo)準(zhǔn)的木材或形鋼的基本原理進(jìn)行了結(jié)構(gòu)設(shè)計(jì),這兩個(gè)鋼筋混凝土異形

18、截面構(gòu)件受力情況是最合理的。我們可以將任何想要的形狀通過(guò)壓縮潮濕的混合物形成正確勻稱的比例,成品變的很堅(jiān)固,耐用,結(jié)合混凝土內(nèi)配筋情況,設(shè)計(jì)成各種受力合理的構(gòu)建。</p><p>  混凝土構(gòu)建類型的不同導(dǎo)致所需的技術(shù)不同即無(wú)論它是一列、梁、墻,一塊,一個(gè)基金會(huì)。一個(gè)大規(guī)模的列,或者一個(gè)擴(kuò)展之前的放置和硬混凝。對(duì)于墻,梁,柱來(lái)說(shuō)表面的清洗應(yīng)該非常靈活,在加固前應(yīng)該及時(shí)清除鐵銹和其他有害物質(zhì)。在基金會(huì)上,地基應(yīng)該夯

19、實(shí),排水,地下水不能影響到混凝土的。通過(guò)高頻振動(dòng)器的機(jī)動(dòng)船根據(jù)實(shí)際需要將混凝土注入到水平層,但是震動(dòng)會(huì)導(dǎo)致混凝土各層隔離或者水分溢出的現(xiàn)象。</p><p>  溫度高于50°F的情況下水泥發(fā)生水化現(xiàn)象,我們需要保持這個(gè)狀態(tài)方便化學(xué)水化反應(yīng)的發(fā)生,如果干燥過(guò)快,會(huì)導(dǎo)致地面開(kāi)裂。地面開(kāi)裂由于裂縫未能獲得全化學(xué)水分,導(dǎo)致混凝土的強(qiáng)度降低。</p><p>  很明顯大量關(guān)于鋼筋混凝土

20、配合比的參數(shù)必須處理,如構(gòu)件的幾何寬度,深度,面積加固,鋼筋應(yīng)變,混凝土應(yīng)變,鋼壓力等等。因此,對(duì)具體部分進(jìn)行試驗(yàn)和調(diào)整是非常必要的,基于現(xiàn)場(chǎng)條件進(jìn)行假設(shè),建筑和空間對(duì)組成材料的有特殊需求,相對(duì)于標(biāo)準(zhǔn)磨捏構(gòu)造梁柱部分的鋼結(jié)構(gòu),適用的法規(guī)和環(huán)境鋼筋混凝土常常是一個(gè)站點(diǎn)構(gòu)造的復(fù)合。</p><p>  在結(jié)構(gòu)體系中,試驗(yàn)部分已經(jīng)被選為各個(gè)關(guān)鍵部分。試驗(yàn)部分必須進(jìn)行分解,來(lái)確定實(shí)際受力是否足以承載力的極限。因?yàn)槌32恢?/p>

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