Composite Beam Sections
Composite beam sections are structural elements made by combining different materials, such as steel and concrete, to create a more efficient and versatile beam. By utilizing the strengths of each material, composite beam sections can achieve greater load-carrying capacity and stiffness compared to traditional beams. This makes them a popular choice in construction for supporting heavy loads over long spans.
7 Key excerpts on "Composite Beam Sections"
- Lawrence Martin, John Purkiss(Authors)
- 2017(Publication Date)
- CRC Press(Publisher)
...Chapter 10 / Composite Construction As mentioned in the introduction to Chapter 8, composite construction for slabs and beams has now become widespread, although some use is still made of pre-cast slabs which whether supported on the top flange of the beam grid or on shelf angles do not act compositely with the supporting beams (although they will provide lateral torsional restraint to the beam). To ensure composite action between the beam and the concrete slab, the two must have adequate shear coupling. In general this is achieved by throughdeck stud welding. A further use of composite construction is concrete filled rolled hollow section columns. This has the effect of both increasing the load carrying capacity and also the fire resistance as the concrete core provides a heat sink, and enables load to be transferred from the steel outer to the core. Construction is fast as the steel section itself acts as formwork for the concrete. Due to developments in alternative, lighter and less time consuming methods of fire protection, concrete for encasement of steel sections, whether beams or columns, is now little used in the UK, even though one of the drawbacks, namely extended construction time and the need for formwork, can be countered by pre-casting the concrete encasement off-site. There will still exist the problems due to the large additional selfweight. Also earlier design methods did not traditionally make full use of the concrete in determining the load carrying capacity (this has changed in EN 1994-1-1). 10.1 C OMPOSITE S LABS A composite slab comprises profile sheet steel decking which acts both as permanent shuttering to the slab and as tension reinforcement for the sagging moments in the slab. There are essentially two basic patterns for profile sheet steel decking; on open trapezoidal section (Fig. 10.1(a)), and a re-entrant trapezoidal section (Fig. 10.1(b))...
eBook - ePub- Andrew H. Buchanan, Anthony Kwabena Abu(Authors)
- 2016(Publication Date)
- Wiley(Publisher)
...8 Composite Structures This chapter describes simple methods of designing composite steel‐concrete structures to resist fires. Composite construction refers to combined structural systems of steel and concrete, where both materials contribute to the load‐bearing capacity. In many composite structures the steel member is partly or fully protected from direct fire exposure by concrete. This chapter describes some common examples of composite construction and provides simple calculation methods of design for fire exposure. This chapter also gives design guidance for the structural fire design of single‐storey and multi‐storey steel frame buildings, with varying levels of composite action. 8.1 Fire Resistance of Composite Elements Structural elements provide fire resistance by satisfying their intensity, insulation and load‐bearing criteria, as specified in the standard fire test. As described in Chapter 4, different building elements would meet one or more of these criteria. Slabs perform a load‐bearing function and separating function. As such they are required to meet all three criteria, while beams and columns are only required to satisfy the load‐bearing criterion. The most common example of composite construction is a concrete slab with a steel deck or a supporting steel beam as shown in Figure 8.1. The steel beam in Figure 8.1 is called a ‘downstand beam’. Sometimes the steel beam is partly or completely buried in the concrete as shown in Figure 8.2. The system with the beam completely buried in the concrete floor slab is often called ‘slim‐floor’. The simple calculation methods outlined in this chapter follow guidance in Eurocode 4 Part 1.2 (CEN, 2005c)...
eBook - ePub- Tim Huff(Author)
- 2021(Publication Date)
- CRC Press(Publisher)
...3 Building Design The following material includes topics not typically covered in undergraduate structural engineering curricula. Nonetheless, the material frequently arises in practice early in engineering careers. A basic understanding of structural steel design in accordance with AISC 360-16 is a prerequisite for a full appreciation of the material presented. 3.1 Composite Beam Design The design of composite beams for buildings will be discussed for both rolled steel shapes and welded plate girders. While welded plate girders are not as common as rolled shapes for building design, the need for such girders does arise. Open areas requiring long spans may necessitate the use of a plate girder in a building. Rigid frames with tapered webs are sometimes found in industrial facilities, and plate girders are needed to accomplish the desired structure. Plate girders are very common in bridge structures. AISC 360-16 (American Institute of Steel Construction, 2016) Chapter I contains basic design criteria for composite beams used in buildings. Deflection criteria are not covered in AISC. These may include requirements for both superimposed loading after the building is in service, and construction requirements prior to deck strength being fully achieved. For example, the owner may require that deflection due to superimposed live load be no more than L /360. This would be the criteria to be satisfied using the composite properties to determine actual deflection. Similarly, the engineer may require that the deflection due to wet concrete plus a construction live load allowance be no greater than L /240. This would be a requirement on the properties of the beam alone. For flexural design of beams, the engineer needs to determine the number and size of shear studs required to transmit horizontal shear between the deck and the beam...
eBook - ePub- A Nash(Author)
- 2017(Publication Date)
- Routledge(Publisher)
...There is no theoretical limit to the length of such a beam. There is, however, a point at which it becomes wasteful to meet the demands of increasing spans by providing deeper solid sections, no matter what the material. Practical size limitations are also imposed by considerations of storage, transportation and erection. The glue lines between the laminations are formed under carefully controlled conditions to ensure a high resistance to horizontal shear, that is the sliding of one lamination on the next one above or below. If this were to happen, the system would consist not of one vertically continuous section but of a succession of individual laminations, with each one passing its load on to the one below. In the extreme condition of totally frictionless interfaces between all of the laminations, the bottom lamination would be trying to act as a 50 mm deep beam, obviously a hopeless task. Reinforced concrete Structural behaviour In Chapter 2, a distinction was drawn between those materials from which structural elements are formed during the construction process, and those which lend themselves to preparation or fabrication before work on site begins. Timber is a naturally occuring material which can be sawn to the dimensions needed for posts, joists, purlins, rafters and other elements of relatively small cross-sectional areas and lengths. It can also be built up into the laminated form described in the previous section. Structural steel is manufactured under conditions of strict quality control, and is also admirably suited to the production of linear elements such as beams and columns, or stanchions as they are frequently referred to in this material. Since steel has strength properties greatly in excess of those of timber, the limit of potential spans and loads is clearly much greater. Reinforced concrete structures are, on the other hand, conditioned by the manner in which they are produced...
eBook - ePubIntroduction to Engineering Mechanics
A Continuum Approach, Second Edition
- Jenn Stroud Rossmann, Clive L. Dym, Lori Bassman(Authors)
- 2015(Publication Date)
- CRC Press(Publisher)
...15 Case Study 7: Engineered Composite Materials In Chapter 14, we noted that some biological materials are “composites,” comprised of multiple materials with significantly different physical properties. The resulting combined materials have characteristics that are different from any of their component materials. Many engineered composite materials are designed with similar objectives, often yielding materials that are stronger, lighter, or less expensive than traditional materials. We characterize the components as “matrix” and “reinforcement;” composite materials should have at least one of each. The matrix material surrounds and supports the reinforcement materials by maintaining their relative positions. The reinforcements impart their particular mechanical and physical properties to enhance the matrix properties. Like biological materials, engineered composites are often anisotropic, due to the orientation of the reinforcements. Engineered composite materials include concrete (and its steel-reinforced form as well), fiber-reinforced plastic (including fiberglass), metal composites, and ceramic composites. 15.1 Concrete Concrete itself is a “composite,” in the sense that it results from the combination of several materials. It is composed of (1) coarse granular aggregate sometimes called filler, embedded in (2) a hard matrix (cement or another binder) that fills the spaces among the aggregate particles and binds them together with the aid of (3) water. The ancient Roman architect/engineer Vitruvius * first wrote down a recipe for concrete—his version included volcanic ash as the binder. The Roman Colosseum was constructed from concrete; more recently, the Hoover Dam and Panama Canal have made good use of this material. It is now the most widely used structural material worldwide. We often use steel bars (which are very strong) to reinforce concrete (which is stronger in compression than in tension)...
eBook - ePubForm and Forces
Designing Efficient, Expressive Structures
- Edward Allen, Waclaw Zalewski(Authors)
- 2012(Publication Date)
- Wiley(Publisher)
...Chapter 18 Bending Resistance in Beams of Any Shape Properties of complex cross-sectional shapes Moment of inertia Composite action Designing bays of steel framing We're designing an 11-story office building that will be framed with structural steel (Figure 18.1). We have reached the stage of preliminary design where we must lay out the frame and determine the sizes of the beams and girders (Figure 18.2). We need to consider the placement of columns in the structural bays, as we discussed in Chapter 15, and we will need to expand our knowledge of the bending resistance of beams from Chapters 16 and 17 to understand how to assign sizes to beams with complex cross-sectional shapes. Figure 18.1 An ironworker guides a wide-flange steel beam toward its position in a building frame. Photo courtesy of Bethlehem Steel Corporation. Figure 18.2 A preliminary floor plan for a small office building. Steel The steel used in structural framing is composed of iron that has been refined so that it contains about three-tenths of 1 percent carbon. This reduction in carbon content produces a metal that is ductile and strong. Today, most steel in the United States is manufactured from recycled steel scrap in electric furnaces. The quality is carefully monitored throughout manufacture to assure that it is very high. Various grades of steel are available in varying strengths, but all structural steels, even those with very high strengths, have the same modulus of elasticity, about 29,000,000 psi. Structural steel is usually designed with an allowable stress in bending of 24,000 psi. Production of Shapes Steel is hot-rolled into structural elements, referred to as shapes, in a steel mill by passing hot steel blanks through a series of specially formed rollers that squeeze the steel into the desired form (Figure 18.3). The hot-rolled shape most commonly used in framing is the wide-flange, a more efficient variation of the now-obsolete American Standard shape often referred to as an I-beam...
eBook - ePub- William Bolton(Author)
- 2012(Publication Date)
- Routledge(Publisher)
...2 Beams and columns 2.1 Introduction As discussed in chapter 1 in relation to possible forms of loading structures, one basic form involves bending. Thus, for the simple beam bridge in Figure 2.1(a) the load arising from a car crossing it will tend to bend the beam. Figure 2.1 Examples of structures where (a) bending (b) compressive loading occurs As also discussed in chapter 1, another form of loading involves the loading in compression. Such members might be concrete or brick columns supporting the floors or roof of a building (Figure 2.2(b)), the applied loads of the floors or roof above applying compressive loads. This chapter is a discussion of loading due to bending, the various forms it can take, and the stresses that can arise from such bending and also the loading of columns. 2.2 Beams A beam can be defined as a structural member, generally horizontal, to which loads are applied and which cause it to bend. As a result of loads causing one surface of a beam to become longer and the opposite surface shorter, when beams bend they become curved. 2.2.1 Types of beams The following are some examples of types of beams: 1 Cantilever (Figure 2.2(a)) This is a beam which is rigidly fixed at just one end, the other end being free. 2 Simply supported beam (Figure 2.2(b)) This is a beam which is supported at its ends on rollers or smooth surfaces or one of these combined with a pin at the other end. 3 Simply supported beam with overhanging ends (Figure 12.2(c)) This is a simple supported beam with the supports set in some distance from the ends. 4 Built-in beam (Figure 2.2(d)) This is a beam which is built-in at both ends and so both ends are rigidly fixed. Figure 2.2 Examples of beams Where an end is rigidly fixed there is a reaction force and a resisting moment. At a supported end or point there are reactions but no resisting moments. At a free end there are no reactions and no resisting moments...
