土木工程专业英语演示课件Unit7.pptVIP

Unit 7 第七单元;教学目标; Concrete and reinforced concrete are used as building materials in every country. In many, including the United States and Canada, reinforced concrete is a dominant（主要的） structural material in engineered construction（建造的建筑物）. The universal（通用的）nature of reinforced concrete construction stems from（归因于）the wide availability of reinforcing bars（钢筋）and the constituents（组成部分）of concrete, gravel,sand, and cement, the relatively simple skills required in concrete construction（施工）, and the economy（经济性）of reinforced concrete compared to other form of construction. Concrete and reinforced concrete are used in bridges, buildings of all sorts（各种各样）, underground structures, water tanks, television towers, offshore oil exploration and production structures（近海石油开采和生产结构）, dams, and even in ships.; 混凝土与钢筋混凝土作为建筑材料在每个国家被使用着。??很多国家，包括美国和加拿大，钢筋混凝土是建造的建筑物中主要的结构材料。钢筋混凝土建筑物通用的特性归因于能大量得到钢筋和混凝土的组分（即碎石、砂和水泥），混凝土施工需要相对简单的技术，以及与其他形式的建筑相比钢筋混凝土的经济性。混凝土与钢筋混凝土用于桥梁、各种房屋、地下结构、水箱、电视塔、近海石油开采和生产结构、大坝甚至船舶。;Mechanics of Reinforced Concrete钢筋混凝土的力学; 混凝土受压强、受拉弱。因此，每当受荷、收缩受阻或温度变化引起的拉应力超过混凝土的抗拉强度时，便会发生开裂。在素混凝土梁中，因外力引起的力矩由内部的拉-压形成的力偶来抵抗，此力偶中包含了混凝土的拉力。当第一条裂缝形成时，此梁会突然、完全地失效。在钢筋混凝土梁中，钢筋埋置在混凝土内的方式应能使混凝土开裂后在钢筋中产生平衡力矩所需的拉力。; The construction（施工）of a reinforced concrete member involves building a form or mold（模具）in the shape of the member being built. The form must be strong enough to support the weight and hydrostatic pressure（静水压力）of the wet concrete, and any forces applied to it by workers, concrete buggies（料车）, wind, and so on. The reinforcement（钢筋）is placed in this form and held in place（固定就位）during the concreting（用混凝土浇筑）operation. After the concrete has hardened, the forms are removed（拆除）. 钢筋混凝土构件的施工包括以在建构件的形状搭建模板或模具。模板必须足够强劲以支承湿混凝土的重量和静水压力，以及任何由工人、混凝土料车、风等施加给它的力。钢筋置于模板中，并在混凝土浇筑过程中固定就位。当混凝土硬化后便拆除模板。; The choice of whether a structure should be built of concrete, steel, masonry, or timber（木材）depends on the availability（可得性）of materials and on