混凝土结构 中英文 PPT 演示文稿

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•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 plastic mix is placed and consolidated in the formwork, then cured to facilitate the acceleration of the chemical hydration reaction lf the
cement/water mix, resulting in hardened concrete.
•素混凝土是由水泥、水、细骨料、粗骨料（碎石或卵石）、空气，通常还有其他外加剂等经过凝固硬化而成。

将可塑的混凝土拌合物注入到模板内，并将其捣实，然后进行养护，以加速水泥与水的水化反应，最后获得硬化的混凝土。

•The finished product has high compressive strength, and low resistance to tension, such that its tensile strength is approximately one tenth lf its compressive strength. Consequently, tensile and shear reinforcement in the tensile regions of sections has to be provided to compensate for the weak tension regions in the reinforced concrete element.
•其最终制成品具有较高的抗压强度和较低的抗拉强度。

其抗拉强度约为抗压强度的十分之一。

因此，截面的受拉区必须配置抗拉钢筋和抗剪钢筋，以增加钢筋混凝土构件中较弱的受拉区的强度。

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It is this deviation in the composition of a reinforces concrete section from the 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 and proportioned that optimal use is made of the materials involved.
•钢筋混凝土截面在均质性上与标准的木材或钢的截面存在着差异，因此，需要对结构设计的基本原理进行修改。

将钢筋混凝土这种非均质截面的两种组成部分按一定比例适当布置，可以最好利用两种材料。

这一要求是可以达到的。

•This is possible because concrete can easily be given any desired shape by placing and compacting the wet mixture of the constituent ingredients are properly proportioned, the finished product becomes strong, durable, and, in combination with the reinforcing bars, adaptable for use as main members of any structural system.
•混凝土由配料搅拌成湿拌合物，经过振捣并凝固硬化，可以做成任何一种需要的形状。

如果拌制混凝土的各种材料配合比恰当，则混凝土制成品的强度较高，经久耐用，配置钢筋后，可以作为任何结构体系的主要构件
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The techniques necessary for placing concrete depend on the type of member to be cast: that is, whether it is a column, a bean, a wall, a slab, a foundation. a mass columns, or an extension of previously placed and hardened 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 compacted and thoroughly moistened to about 6 in. in depth to avoid absorption of the moisture present in the wet concrete.
浇筑混凝土所需要的技术取决于即将浇筑的构件类型，诸如：柱、梁、墙、板、基础，大体积混凝土水坝或者继续延长已浇筑完毕并且已经凝固的混凝土等。

对于梁、柱、墙等构件，当模板清理干净后应该其上涂油，钢筋表面的锈及其他有害物质也应该被清除干净。

浇筑基础前，应将坑底土夯实并用水浸湿6英寸，以免土壤从
新浇的混凝土中吸收水分。

Concrete should always be placed in horizontal layers which are compacted by means of high frequency power-driven vibrators of either the immersion or external type, as the case requires, unless it is placed by pumping. It must be kept in mind, however, that over vibration can be harmful since it could cause segregation of the aggregate and bleeding of the concrete.
一般情况下，除使用混凝土泵浇筑外，混凝土都应在水平方向分层浇筑，并使用插入式或表面式高频电动振捣器捣实。

必须记住过分的振捣将导致骨料离析和混凝土泌浆等现象，因而是有害的。

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•Hydration of the cement takes place in the presence of moisture at temperatures above 50°F. It is necessary to maintain such a condition 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 attain full chemical hydration.
•水泥的水化作用发生在有水分存在，而且气温在50°F以上的条件下。

为了保证水泥的水化作用得以进行，必须具备上述条件。

如果干燥过快则会出现表面裂缝，这将有损于混凝土的强度，同时也会影响到水泥水化作用的充分进行。

•A trial section has to be chosen for each critical location in a structural system. The 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 design input step generates into a series of trial-and-adjustment analyses.
验算很必要！
•对结构体系的各个部位均需选定试算截面并进行验算，以确实该截面的名义强度是否足以承受所作用的计算荷载。

由于经常需要进行多次验算，才能求出所需的截面，因此设计时第一次采用的数值将导致一系列的试算与调整工作。

•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 reinforcement, steel strain, concrete strain, steel stress, and so on.
•设计钢筋混凝土构件时必须需要处理大量的参数，诸如宽度、高度等几何尺寸，配筋的面积，钢筋的应变和混凝土的应变，钢筋的应力等等。

•Consequently, trial and adjustment is necessary in the choice of concrete sections, with assumptions based on conditions at site, availability of the constituent materials, particular demands of the owners, architectural and headroom requirements, the applicable codes, and environmental reinforced concrete is often a site-constructed composite, in contrast to the standard mill-fabricated beam and column sections in steel structures.
•The trial-and –adjustment procedures for the choice of a concrete section lead to the
convergence of analysis and design. Hence
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 method compared with the traditional
approach of treating the analysis of
reinforced concrete separately from pure
design.
•选择混凝土截面时，采用试算与调整过程可以使复核和设计结合在一起。

因此，当试算截面选定后，每次设计都是对截面进行复核。

手册、图表和微型计算机以及专用程序的使用，使这种设计方法更为简捷有效，而传统的方法则是把钢筋混凝土的复核与单纯的设计分别进行处理。