建筑工程专业英语unit6

1、Lesson 5 Building Mechanics Building mechanics is studied about the working condition of the structures and components applied the loads or other factors, which is the strength, stiffness and stability of buildings. It is a very wide range of areas, including theoretical mechanics, material mechanic

2、s, structural mechanics, elastic mechanics, plastic mechanics, structural dynamics, and so on. As for the Building Engineering College students, our focus is on theoretical mechanics, material mechanics and structural mechanics, known as three mechanics. mechanics力学，机械学load负荷，荷载strength强度 Theoretica

3、l mechanics It is a discipline that studies general rules of the mechanical movement among or between objects. The content includes statics, kinematics and dynamics. In theoretical mechanics course, our focus is on statics. statics静力学kinematics运动学 dynamics动力学 Statics mainly studies the balance of ob

4、jects acted forces on, and how to create the balance conditions under various force systems. At the same time, statics is also the basic methods, by which to study the simplification of the force system and the mechanical analysis of the object. There are three basic static physical parameters: forc

5、e, couple and moment. couple力偶moment力矩 The almost full content of statics is deduced on the base of several Justices. The Justices, who are known as the summary of the knowledge accumulated by peoples in the production of long-term practice, reflects the simplest and basic attribute of the force act

6、ing on the rigid body. The accuracy of these can be verified by experiment, but not be proved by the more fundamental principles. rigid body刚体 Justice公理 According to the research methods, statics can be divided into the geometric statics and the analytic statics. Applying the geometric statics, we c

7、an use analytical method or graphic method to study the static problems. While, we can base the analytic statics on the virtual displacement principle and know the analytic way as the major research means1. It established general roles of the balance of arbitrary force systems; therefore, the analyt

8、ic statics is more common approaches. the virtual displacement principle虚位移原理 In engineering, the statics shares a wide range of applications, for example, the analysis of houses and bridges, the analysis and calculation of loads, etc. The statics also is known as a foundation of material mechanics

9、and structural mechanics. After theoretical mechanics courses, students should be able to abstract the simple practical problems in practice work to the static model to analyze the balance and the force of the objects; to carry out the calculation about general force systems; to analyze a simple mov

10、ement about a point or a rigid body. abstract使抽象化;抽取,提取 Fig 6.1 Simple beamMaterial mechanics It is a research about stress, strain, strength and stiffness in various forces, and the limits when all kinds of material damage. All engineering students must study this course, because it is necessary to

11、 the structural design. In the course of material mechanics, students should have a basis of higher mathematics and theoretical mechanics. strain应变 The main task of material mechanics course is to study the destruction law of materials acted forces on, which may be steel, concrete, wood, plastic, an

12、d so on, and the requested strength, stiffness and stability of bars, who may be beams, columns, and other components those length is more than twice horizontal sizes; to solve the contradiction between structural reliability and economic reasonableness. destruction law破坏机制 Ignoring secondary factor

13、s, simplifying and abstracting components, the following basic assumptions are given in material mechanics:1. Continuity assumption - a material is continuous and non-porous; 2. Uniformity assumption - a material shows the same nature in different parts; 3. Isotropic assumption -a material shows the

14、 same nature in different directions; 4. Small deformation assumption the deformation of a material is far smaller than the size of components, so as to calculating under the original size and geometry. non-porous 无孔的 isotropic各向同性deformation 变形 Through material mechanics courses, students should be

15、 able to calculate the stiffness and the strength, when simple deformation comes on the straight bar in pulling, pushing, cutting, twisting, bending； to calculate the stress and strength, when skew bending, eccentric compression (tension), bending and torsion comes on the combined deformation; to un

16、derstand the purposes and ways of the basic experiments. stress应力 eccentric偏心的 Fig 6.2 and in bendingStructural mechanics It is a discipline major to study the law of structures bearing and transferring loads, and how to optimize the structure. Here, the structure means the system that can bear and

17、transfer loads, including rods, plates, shells and their combinations, such as bridges, roof trusses and load-bearing walls, and so on2. roof truss屋架 The main task of structural mechanics course is to study the laws of stress, strain and displacement, when the loads are acted on the structures; to a

18、nalyze engineering structures, who are made up of different materials or forms, in order to provide analytic methods and calculable formulas for engineering design; to identify the ability of bearing and transferring loads; to research and develop new type engineering structures. Finishing structura

19、l mechanics courses, students should be able to choose structural calculating diagram; to carry on the analysis to the geometrical composition of the system; to analyze the internal forces of the static set beams, steel frames, trusses; to understand the methods of calculation of hyperstatic structu

20、re including the force method, the displacement method, the moment distribution method, and the shear distribution method.calculating diagram计算简图steel frame钢框架hyperstatic structure超静定结构12321ABCC3.0m3.0m3.0m3.0mBA3.0mqFig 6.3 Hyperstatic structure Structural mechanics isnt only an ancient discipline, but also a rapidly developing discipline. Numbers of new materials and new structures coming on can provide a new research and put forward new demand. The development of computer may provide a powerful tool for structural mechanics. On the ot