四川交通职业技术学院 Sichuan Vocational &Technical College of Communications 土木工程英语 四川交通职业技术学院教学课件 (The 2nd Talent-Competition for Teachers of SVTCC) 国家示范性高等职业技术学院 教师：黄 蜀 云 公共课教学部 Unit 6 Stress & Deformation

English for Civil Engineering ～ Road Engineering 四川交通职业技术学院 Sichuan Vocational &Technical College of Communications 国家示范性高等职业技术学院 | Lead-in( 导入 ) | Dialogue( 对话 ) |Text ( 课文 ) | Exercises( 练习 ) |Guided Writing( 写作 )| Lead-in 黄蜀云 Stress is the physical pressure or other forces exerted on an object. Deformation in any direction is the total change in the dimension of a member in that direction. Deformation Force

English for Civil Engineering ～ Road Engineering 四川交通职业技术学院 Sichuan Vocational &Technical College of Communications 国家示范性高等职业技术学院 | Lead-in( 导入 ) | Dialogue( 对话 ) |Text ( 课文 ) | Exercises( 练习 ) |Guided Writing( 写作 )| Lead-in 黄蜀云 pre-stressing operating Work platform Ancho r bolts rebar concrete

English for Civil Engineering ～ Road Engineering 四川交通职业技术学院 Sichuan Vocational &Technical College of Communications 国家示范性高等职业技术学院 | Lead-in( 导入 ) | Dialogue( 对话 ) |Text ( 课文 ) | Exercises( 练习 ) |Guided Writing( 写作 )| Dialogue 黄蜀云 A: Since many pre-stressing reinforced concrete components are adopted in project, it is necessary to have a look at the pre-stressing operating. fixing formwork exerting tension

English for Civil Engineering ～ Road Engineering 四川交通职业技术学院 Sichuan Vocational &Technical College of Communications 国家示范性高等职业技术学院 | Lead-in( 导入 ) | Dialogue( 对话 ) |Text ( 课文 ) | Exercises( 练习 ) |Guided Writing( 写作 )| Dialogue 黄蜀云 B : The rebar is pre-stressed first by a certain tension force and fixed on both ends. Then we fix the formwork and non-prestressed rebar, and then pour concrete. After the concrete reaches the designed strength, the pre-stressed rebar are released. pouring concrete releasing rebar

English for Civil Engineering ～ Road Engineering 四川交通职业技术学院 Sichuan Vocational &Technical College of Communications 国家示范性高等职业技术学院 | Lead-in( 导入 ) | Dialogue( 对话 ) |Text ( 课文 ) | Exercises( 练习 ) |Guided Writing( 写作 )| Dialogue 黄蜀云 B : The rebar is pre-stressed first by a certain tension force and fixed on both ends. Then we fix the formwork and non-prestressed rebar, and then pour concrete. After the concrete reaches the designed strength, the pre-stressed rebar are released. releasing rebar pouring concrete

English for Civil Engineering ～ Road Engineering 四川交通职业技术学院 Sichuan Vocational &Technical College of Communications 国家示范性高等职业技术学院 | Lead-in( 导入 ) | Dialogue( 对话 ) |Text ( 课文 ) | Exercises( 练习 ) |Guided Writing( 写作 )| Dialogue 黄蜀云 A: The strength from the pre- stressing members is transferred to the concrete, isn’t it ? B: Yes. The pre-stressed concrete will offset some or all the tension force when it is under the situation of tension strength. rebar offset the tension force Pressure

English for Civil Engineering ～ Road Engineering 四川交通职业技术学院 Sichuan Vocational &Technical College of Communications 国家示范性高等职业技术学院 | Lead-in( 导入 ) | Dialogue( 对话 ) |Text ( 课文 ) | Exercises( 练习 ) |Guided Writing( 写作 )| Dialogue 黄蜀云 A: Are there any differences between the pre-stressed concrete and non-prestressed concrete in concrete pouring? B: In order to reduce the concrete shrinkage under the pre- stressing, the pre-stressed concrete should be poured continuously in one time without construction joints. the ratio of water and cement should be low and the aggregate should be selected in better quality. construction joints

English for Civil Engineering ～ Road Engineering 四川交通职业技术学院 Sichuan Vocational &Technical College of Communications 国家示范性高等职业技术学院 | Lead-in( 导入 ) | Dialogue( 对话 ) |Text ( 课文 ) | Exercises( 练习 ) |Guided Writing( 写作 )| Dialogue 黄蜀云 A: When can the fixtures of the pre–stressed rebar be removed ? B: It depends on whether the concrete strength reaches the designed value or not. At least the test should show that the result is up to the standard. if the fixture are released too early, it will cause lots of strength loss and even serious quality problem.

English for Civil Engineering ～ Road Engineering 四川交通职业技术学院 Sichuan Vocational &Technical College of Communications 国家示范性高等职业技术学院 | Lead-in( 导入 ) | Dialogue( 对话 ) |Text ( 课文 ) | Exercises( 练习 ) |Guided Writing( 写作 )| Dialogue 黄蜀云 Technical Terms of the Dialogue 1. 模板 2. 水泥 3. 骨料 4. 钢筋混凝土 5. 预应力 6. 预应力钢筋 7. 施工缝 8. 拉 ( 张 ) 力

English for Civil Engineering ～ Road Engineering 四川交通职业技术学院 Sichuan Vocational &Technical College of Communications 国家示范性高等职业技术学院 | Lead-in( 导入 ) | Dialogue( 对话 ) |Text ( 课文 ) | Exercises( 练习 ) |Guided Writing( 写作 )| Dialogue 黄蜀云 Group WorkGroup Work Try to explain in your own words the technical terms learned in the dialogue and then talk about the process of pre-stressing operation.

English for Civil Engineering ～ Road Engineering 四川交通职业技术学院 Sichuan Vocational &Technical College of Communications 国家示范性高等职业技术学院 | Lead-in( 导入 ) | Dialogue( 对话 ) |Text ( 课文 ) | Exercises( 练习 ) |Guided Writing( 写作 )| Text 黄蜀云 When designing a structure,the designer must estimate all the forces acting on the structure and its component parts. The effects of the forces are then considered in relation to the stability of a building as a whole and component parts are made strong enough to carry their particular function.

English for Civil Engineering ～ Road Engineering 四川交通职业技术学院 Sichuan Vocational &Technical College of Communications 国家示范性高等职业技术学院 | Lead-in( 导入 ) | Dialogue( 对话 ) |Text ( 课文 ) | Exercises( 练习 ) |Guided Writing( 写作 )| Text 黄蜀云 The forces to be considered depend on the type and purpose of the structure. In buildings,for example,the forces will be due to the weight of the structure and its occupants as well as to the pressure exerted by wind.

English for Civil Engineering ～ Road Engineering 四川交通职业技术学院 Sichuan Vocational &Technical College of Communications 国家示范性高等职业技术学院 | Lead-in( 导入 ) | Dialogue( 对话 ) |Text ( 课文 ) | Exercises( 练习 ) |Guided Writing( 写作 )| Text 黄蜀云 The loads of a building

English for Civil Engineering ～ Road Engineering 四川交通职业技术学院 Sichuan Vocational &Technical College of Communications 国家示范性高等职业技术学院 | Lead-in( 导入 ) | Dialogue( 对话 ) |Text ( 课文 ) | Exercises( 练习 ) |Guided Writing( 写作 )| Text 黄蜀云 In the wall for retaining earth,the forces will be due to the weight of the wall, the pressure exerted on the wall by the earth behind it,and the pressure due to any buildings or roadways near the top of the wall. 挡土墙受力

English for Civil Engineering ～ Road Engineering 四川交通职业技术学院 Sichuan Vocational &Technical College of Communications 国家示范性高等职业技术学院 | Lead-in( 导入 ) | Dialogue( 对话 ) |Text ( 课文 ) | Exercises( 练习 ) |Guided Writing( 写作 )| Text 黄蜀云 The internal fibers or particles of the various parts of a structure are put into a state of stress by the forces they are needed to resist,the basic forms of stress being tension, compression,shear and torsion. b a tension compression

English for Civil Engineering ～ Road Engineering 四川交通职业技术学院 Sichuan Vocational &Technical College of Communications 国家示范性高等职业技术学院 | Lead-in( 导入 ) | Dialogue( 对话 ) |Text ( 课文 ) | Exercises( 练习 ) |Guided Writing( 写作 )| Text 黄蜀云 In tension,the material is pulled apart or stretched like a rubber band. In compression,the material is pressed or pushed together.

English for Civil Engineering ～ Road Engineering 四川交通职业技术学院 Sichuan Vocational &Technical College of Communications 国家示范性高等职业技术学院 | Lead-in( 导入 ) | Dialogue( 对话 ) |Text ( 课文 ) | Exercises( 练习 ) |Guided Writing( 写作 )| Text 黄蜀云 What is torsion ?It makes the structure rotate or turn. torsion

English for Civil Engineering ～ Road Engineering 四川交通职业技术学院 Sichuan Vocational &Technical College of Communications 国家示范性高等职业技术学院 | Lead-in( 导入 ) | Dialogue( 对话 ) |Text ( 课文 ) | Exercises( 练习 ) |Guided Writing( 写作 )| Text 黄蜀云 The shearing force causes shearing stress. It is defined as the fracture of the materials along the stress route. shear F F

English for Civil Engineering ～ Road Engineering 四川交通职业技术学院 Sichuan Vocational &Technical College of Communications 国家示范性高等职业技术学院 | Lead-in( 导入 ) | Dialogue( 对话 ) |Text ( 课文 ) | Exercises( 练习 ) |Guided Writing( 写作 )| Text 黄蜀云 Since the structure designed by civil engineers is intended to be stable,these forces must be kept in balance. The vertical forces,for example,must be equal to each other. if a beam supports a load above,the beam itself must have sufficient strength to counterbalance that weight. F1 F2 F1F2=

English for Civil Engineering ～ Road Engineering 四川交通职业技术学院 Sichuan Vocational &Technical College of Communications 国家示范性高等职业技术学院 | Lead-in( 导入 ) | Dialogue( 对话 ) |Text ( 课文 ) | Exercises( 练习 ) |Guided Writing( 写作 )| Text 黄蜀云 The horizontal forces must also be equal to each other so that there is not too much thrust either to the right or to the left.the forces that might pull the structure around must be counterbalanced with forces that pull in the opposite direction. F1 F2= F1

English for Civil Engineering ～ Road Engineering 四川交通职业技术学院 Sichuan Vocational &Technical College of Communications 国家示范性高等职业技术学院 | Lead-in( 导入 ) | Dialogue( 对话 ) |Text ( 课文 ) | Exercises( 练习 ) |Guided Writing( 写作 )| Text 黄蜀云 if a man carries a heavy load,his body is distressed as a result of the efforts he has to make to bear the load. In order to grasp the idea of stress, it is helpful to compare fibers of a material subjected to force to the bones and muscles of a man.

English for Civil Engineering ～ Road Engineering 四川交通职业技术学院 Sichuan Vocational &Technical College of Communications 国家示范性高等职业技术学院 | Lead-in( 导入 ) | Dialogue( 对话 ) |Text ( 课文 ) | Exercises( 练习 ) |Guided Writing( 写作 )| Text 黄蜀云 A material is sure to deform to a greater or lesser extent when it is subjected to stress,although the dimensional variations in structural materials are usually very slight.the deformation produced is often called strain.a member stressed in compression becomes shorter and fatter.

English for Civil Engineering ～ Road Engineering 四川交通职业技术学院 Sichuan Vocational &Technical College of Communications 国家示范性高等职业技术学院 | Lead-in( 导入 ) | Dialogue( 对话 ) |Text ( 课文 ) | Exercises( 练习 ) |Guided Writing( 写作 )| Text 黄蜀云 Questions 1.What should a designer estimate in designing a structure 2.What are the four basic forms of stress? 3.How can the forces of the structure be kept in balance? 4.In what condition does a material deform? Take an example 1.What should a designer estimate in designing a structure 2.What are the four basic forms of stress? 3.How can the forces of the structure be kept in balance? 4.In what condition does a material deform? Take an example

English for Civil Engineering ～ Road Engineering 四川交通职业技术学院 Sichuan Vocational &Technical College of Communications 国家示范性高等职业技术学院 | Lead-in( 导入 ) | Dialogue( 对话 ) |Text ( 课文 ) | Exercises( 练习 ) |Guided Writing( 写作 )| Text 黄蜀云 Answers 1.He must estimate all the forces acting on the structure and its component parts as well as the stability of the building. 2.Tension, compression, shear and torsion. 3.See Para.2 4. A material is sure to deform to a greater or less extent when it is subjected to stress. If a man carries a heavy load, his body is distressed as a result of the efforts he has to make to bear the load. 1.He must estimate all the forces acting on the structure and its component parts as well as the stability of the building. 2.Tension, compression, shear and torsion. 3.See Para.2 4. A material is sure to deform to a greater or less extent when it is subjected to stress. If a man carries a heavy load, his body is distressed as a result of the efforts he has to make to bear the load.

English for Civil Engineering ～ Road Engineering 四川交通职业技术学院 Sichuan Vocational &Technical College of Communications 国家示范性高等职业技术学院 | Lead-in( 导入 ) | Dialogue( 对话 ) |Text ( 课文 ) | Exercises( 练习 ) |Guided Writing( 写作 )| GUIDED WRITING 黄蜀云 表格是用列表的形式将文字或数字排列出来，以获得一目了然的 效果。表格大体可分为需要读者填写的表格（如订单）和提供某种 信息的列表（如价目表和简历表）两类，内容一般包括图表和说明 文字两部分。说明文字多用完整的句子，而图表的文字一般使用单 词或短语。 １. Subscription Form （订单） ２. Resume （履历表） 表格是用列表的形式将文字或数字排列出来，以获得一目了然的 效果。表格大体可分为需要读者填写的表格（如订单）和提供某种 信息的列表（如价目表和简历表）两类，内容一般包括图表和说明 文字两部分。说明文字多用完整的句子，而图表的文字一般使用单 词或短语。 １. Subscription Form （订单） ２. Resume （履历表）

English for Civil Engineering ～ Road Engineering 四川交通职业技术学院 Sichuan Vocational &Technical College of Communications 国家示范性高等职业技术学院 | Lead-in( 导入 ) | Dialogue( 对话 ) |Text ( 课文 ) | Exercises( 练习 ) |Guided Writing( 写作 )| GUIDED WRITING 黄蜀云 See You !