1、1 XXXXXXXXX 学院 学士学位毕业设计（论文）英语翻译 课 题 名 称 英语翻译 学 号 学 生 专 业、年级 所 在 院 系 指 导 教 师 选 题 时 间 2 Fundamental Assumptions for Reinforced Concrete Behavior The chief task of the structural engineer is the design of structures. Design is the determination of the general shape and all specific dimensions of a part
2、icular structure so that it will perform the function for which it is created and will safely withstand the influences that will act on it throughout useful life. These influences are primarily the loads and other forces to which it will be subjected, as well as other detrimental agents, such as tem
3、perature fluctuations, foundation settlements, and corrosive influences, Structural mechanics is one of the main tools in this process of design. As here understood, it is the body of scientific knowledge that permits one to predict with a good degree of certainly how a structure of give shape and d
4、imensions will behave when acted upon by known forces or other mechanical influences. The chief items of behavior that are of practical interest are (1) the strength of the structure, i. e. , that magnitude of loads of a give distribution which will cause the structure to fail, and (2) the deformati
5、ons, such as deflections and extent of cracking, that the structure will undergo when loaded under service condition. The fundamental propositions on which the mechanics of reinforced concrete is based are as follows: 1. The internal forces, such as bending moments, shear forces, and normal and shea
6、r stresses, at any section of a member are in equilibrium with the effect of the external loads at that section. This proposition is not an assumption but a fact, because any body or any portion thereof can be at rest only if all forces acting on it are in equilibrium. 2. The strain in an embedded r
7、einforcing bar is the same as that of the surrounding concrete. Expressed differently, it is assumed that perfect bonding exists between concrete and steel at the interface, so that no slip can occur between the two materials. Hence, as the one deforms, so must the other. With modern deformed bars,
8、a high degree of mechanical interlocking is provided in addition to the natural surface adhesion, so this assumption is very close to correct. 3. Cross sections that were plane prior to loading continue to be plan in the member under load. Accurate measurements have shown that when a reinforced conc
9、rete member is loaded close to failure, this assumption is not absolutely accurate. However, the deviations are usually minor. 4. In view of the fact the tensile strength of concrete is only a small fraction of 3 its compressive strength； the concrete in that part of a member which is in tension is
10、usually cracked. While these cracks, in well-designed members, are generally so sorrow as to be hardly visible, they evidently render the cracked concrete incapable of resisting tension stress whatever. This assumption is evidently a simplification of the actual situation because, in fact, concrete
11、prior to cracking, as well as the concrete located between cracks, does resist tension stresses of small magnitude. Later in discussions of the resistance of reinforced concrete beams to shear, it will become apparent that under certain conditions this particular assumption is dispensed with and adv
12、antage is taken of the modest tensile strength that concrete can develop. 5. The theory is based on the actual stress-strain relation ships and strength properties of the two constituent materials or some reasonable equivalent simplifications thereof. The fact that novelistic behavior is reflected i
13、n modern theory, that concrete is assumed to be ineffective in tension, and that the joint action of the two materials is taken into consideration results in analytical methods which are considerably more complex and also more challenging, than those that are adequate for members made of a single, s
14、ubstantially elastic material. These five assumptions permit one to predict by calculation the performance of reinforced concrete members only for some simple situations. Actually, the joint action of two materials as dissimilar and complicated as concrete and steel is so complex 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 becomes available.
