15376建筑工程专业英语

1、Lesson 7 Building Structures A structure is the part of a building that carries its weight. A structure may be a dwelling house, or a pyramid in Egypt, or a dam on a river. A building is a structure with a roof and much of civil engineering structural design is the design of building structure. The

2、part of the building that holds up the weight and load is called the structural part. Parts such as windows that do not hold up the building are the non-structural parts. structure 结构dwelling 居住dam 坝体 Building structures are classified many forms according to the different material, such as concrete

3、 structure, steel structure and masonry structure. Concrete structure is classified three forms, such as reinforced concrete, prestressed concrete and plain concrete.concrete structure 混凝土结构steel structure钢结构masonry structure砌体结构reinforced concrete钢筋混凝土prestressed concrete预应力混凝土plain concrete素混凝土Rei

4、nforced Concrete Structures In reinforced concrete structures, steel reinforcing bars are embedded in concrete structures where tensile stress may occur to make the good compressive strength of concrete structures fully put into action1. Generally speaking, reinforced concrete structures possess the

5、 following features：large dead mass, high stiffness, good durability, long curing period, easily cracked and so on. compressive strength抗压强度dead mass自重curing period养护期 durability耐久性 Reinforced concrete systems are composed of a variety of concrete structural elements that, when synthesized, produce

6、a total system. The components can be broadly classified into：floor slabs, beams, columns, walls and foundations .element构件synthesize整浇floor slab楼板beam梁column柱foundation基础Fig 7.1 Typical reinforced concrete framing structure Floor slabs are the main horizontal elements that transmit live loads as we

7、ll as dead loads to the vertical framing supports of a structure. They can be proportioned such that they act in one direction (one-way slabs) or proportioned so that they act in two perpendicular directions (two-way slabs). horizontal水平，横向frame structure 框架结构one-way slab单向板two-way slab双向板 Beams are

8、 the structural elements that transmit the loads from floor slabs to vertical supporting columns. They are normally cast with the slabs and are structurally reinforced on one face, the lower tension side, or both the top and bottom faces. As they are cast with the slab, they form a T-beam section fo

9、r interior beams or an L beam at the building exterior.tention拉力 Columns are the vertical elements that support the structural floor system. They are compression member subjected in most cases to both flexural moment and axial force, and are of major importance in the safety considerations of any st

10、ructure. flexural moment弯矩axial force轴力 Walls are the vertical enclosures for building frames. They are not usually or necessarily made of concrete but of any material that aesthetically fulfills the form and functional needs of the structural system. Additionally structural concrete walls are often

11、 necessary as foundation walls, stairwell wall, and shear walls that resist horizontal wind loads and earthquake-induced loads. enclosure围护结构shear walls 剪力墙earthquake地震 Foundations are the structural concrete elements that transmit the weight of the superstructure to the supporting soil. They could

12、be in many forms, the simplest being the isolated footing. Because of the ways that buildings are made to hold up weight, building structures can be divided into different types, such as framed structure, shear wall structure, wall-framed structure and tube structures2.superstructure 上部结构isolated fo

13、oting 独立基础wall-framed 框架剪力墙tube筒体Framed structure Structural systems composed of elements that are long compared with their cross-sectional dimensions are referred to as framed structure, such as beam and column. The elements of a framed structure are defined as linear element since they can transfe

14、r the support of loads in only one direction, that is, along the length of the element. cross-sectional 横截面Fig7.2 Framed structure Shear wall structure Concrete continuous vertical walls may serve both architecturally as partitions and structurally to carry gravity and lateral loading. Their very hi

15、gh inplane stiffness and strength makes them ideally suited for bracing multi-story building and tall buildings. In a shear wall structure, such walls are entirely responsible for the lateral load resistance of the buildings. They act as vertical cantilevers in the form of separate planar walls, and

16、 as nonplanar assemblies of connected walls around elevator, stair, and service shafts. Because they are much stiffer horizontally than rigid frames, shear wall structure can be economical up to 35 stories. stiffness 刚度cantilever悬臂梁 planarl平面 Fig7.3 Shear wall structureWall-frame structure When shea

17、r walls are combined with frames, the walls, which tend to deflect in a flexural configuration, and the frame, which tend to deflect in a shear mode, are constrained to adopt a common deflected shape by the horizontal rigidity of the girder and slabs. As a consequence, the walls and frames interact

18、horizontally, especially at the top, to produce a stiffer and stronger structure. The interacting wall-frame combination is appropriate for buildings in the 40 to 60 story range, well beyond that of rigid frames or shear walls alone .Fig7.4 Wall-frame structureWall-frame structure Tube structure The

19、 maximum efficiency of the total structure of a tall building, for both strength and stiffness to resist wind load can be achieved only if all column element can be connected to each other. In such way the entire building acts as a hollow tube or rigid box in projecting out of the ground，that is tub

20、e structure. hollow 中空的Fig7.5 Tube structure 筒体结构Prestressed Concrete Structure Prestressed concrete is basically concrete in which internal stresses counteracts external loads to a desired degree. In reinforced concrete members, the prestress is commonly introduced by tensioning the steel reinforce

21、ment. Method of prestressing the concrete: the pre-tension method and the past-tension method.pre-tension method 先张法past-tension method后张法 The use of high strength material results in a reduction in the cross sectional dimensions of prestressed concrete structural elements，with reduced dead weight o

22、f the material, longer spans e technically and economically practicable.Masonry structure The earliest use of masonry can be traced back to two thousand years ago in China. Before the use of reinforced concrete, masonry such as stone, brick were the main construction materials. Even in the modern ti

23、me, due to its good quality of heat preservation and easy manufacture and construction, most countries especially developing countries are using it as main material for civil buildings. The masonry structure takes the role place in developing countries for its lower cost. But as known to all, masonr

24、y material such as brick or block is a type of brittle material. Its compressive capacity is strong, however, its tensile capacity is weak and its poor deformability or ductility characteristic. Buildings built by ductile materials can endure severe earthquake and would not fall down even seriously

25、damaged, but those built by brittle materials would suddenly fall down once the earthquake load exceeds its resistant capacity. Thus, some strict limitations have to be specified to these areas where they may encounter severe earthquakes. brittle 脆性的ductility 延性1-longitudinal masonry wall; 2-constru

26、ctional column ; 3-ring beam;4- joint motor; 5-horizontal masonry wallFig7.6 Composite masonry (CM) structure Researches had advanced several approaches to get competent ductile masonry structures for earthquake region. One of them is composite masonry (CM) structure. The CM structure is a structure

27、 that has some small reinforced concrete columns to be inserted into the masonry wall and to envelop the wall with beams3. The position, dimension, number, and reinforcement of the RC columns might to be decided. Unlike the masonry-infilled RC frame structure, the masonry in CM structure is construc

28、ted before concrete pouring. After the pouring of columns and beams, the masonry wall is well connected with the concrete members through the shear keys in columns and horizontal connecting steel bars lay between columns and block units in joint mortar. By this way, both concrete and masonry members

29、 of the structure are restricted to each other and can deform harmoniously. Due to the property of restriction, we named the RC column as constructional column and the beam as ring beam. In such a structure, cracks are expected to take place firstly in masonry, then in RC columns after diagonal crac

30、ks penetrate the masonry and begin to slide. This approach is widely accepted and used in China. The trace investigations show that even the temperature cracks are hardly to be found in such buildings, which means excellent integrality of the structures. Steel Structures Steel structure refers to a

31、broad of building structures in which steel plays the leading role. Steel offers much better compression and tension capacity than concrete and enables lighter construction. Steel structures use three-dimensional trusses, so they can be larger than reinforced concrete. Tension Member The tension mem

32、ber occurs commonly as a chord member in a truss, as diagonal bracing in many types of structures, as direct support for balconies, and as suspension bridge main cables and suspenders that support the roadway. Round and rectangular bars (b) cables composed of many small wires (c) Single and double a

33、ngles (d) Rolled W-and I-section (e) T Section (f) Built-up box sectionsFig7.7 Typical tension membersCompression Member Chord members in trusses, and many interior columns in buildings are examples of members subject to axial compression. Even under the most ideal condition, pure axial compression

34、is not attainable; so design for axial loading assumes that the effect of any small bending may be neglected. (a) Rolled W-and I-shapes section (b) double angle (c) T Section (d) Structural tubing (e) Pipe section (t) Built-up sections Fig 7.8 Typical compression membersBeams Beams are members subje

35、cted to transverse loading and are most efficient when their area is distributed to be located at the greatest practical distance from the neutral axis. The most common beam sections are the wide-flange and I-beams as well as smaller rolled I-shaped sections designated as“ miscellaneous shapes”. For deeper and thinner-webbed sections then can economically be rolled, welded I-shaped sections are used, including stiffened plate girder. For moderate spans carrying light loads, open-web joists are