Bolted Joint
A bolted joint is a mechanical connection between two or more components using bolts and nuts. It is a common method for fastening and securing parts in various engineering applications. The joint relies on the clamping force generated by tightening the bolts to hold the components together.
8 Key excerpts on "Bolted Joint"
- N.S. Trahair, M.A. Bradford, David Nethercot, Leroy Gardner(Authors)
- 2017(Publication Date)
- CRC Press(Publisher)
...General guidance on joints is given in [ 2 – 11 ]. 9.2 Joint components 9.2.1 Bolts Several different types of bolts may be used in structural joints, including ordinary structural bolts (i.e. commercial or precision bolts and black bolts), and high-strength bolts. Turned close tolerance bolts are now rarely used. Bolts may transfer loads by shear and bearing, as shown in Figure 9.1 a, by friction between plates clamped together as shown in the preloaded friction-grip joint of Figure 9.1 b, or by tension as shown in Figure 9.1 c. The shear, bearing, and tension capacities of bolts and the slip capacities of preloaded friction-grip joints are discussed in Section 9.6. Figure 9.1 Use of bolts in joints. The use of bolts often facilitates the assembly of a structure, as only very simple tools are required. This is important in the completion of site joints, especially where the accessibility of a joint is limited, or where it is difficult to provide the specialised equipment required for other types of fasteners. On the other hand, bolting usually involves a significant fabrication effort to produce the bolt holes and the associated plates or cleats. In addition, special but not excessively expensive procedures are required to ensure that the clamping actions required for preloaded friction-grip joints are achieved. Precautions may need to be taken to ensure that the bolts do not become undone, especially in situations where fluctuating or impact loads may loosen them. Such precautions may involve the provision of special locking devices or the use of preloaded high-strength bolts. Guidance on bolted (and on riveted) joints is given in [ 2 – 11 ]. 9.2.2 Pins Pin joints used to be provided in some triangulated frames where it was thought to be important to try to realise the common design assumption that these frames are pin-jointed...
eBook - ePub- Sayed M. Metwalli(Author)
- 2021(Publication Date)
- Wiley(Publisher)
...9 Screws, Fasteners, and Permanent Joints This chapter intends to present screws, fasteners, and permanent joints. Standards and types of threads including their geometry, designation, and internal stresses are presented. Modeling bolted connections joining few members are suggested to allow the evaluation of preloading due to tightening and stresses generated in the bolt and members under loading. As an application of threaded members, power screws are useful in mechanical applications such as jacks, vices, and presses. Torques that can be developed by power screws and the subsequent internal stresses are developed. Permanent joints that connect components without any dismantling option such as rivets, welding, and bonding are important tools of lifelong joining. These techniques are available for some machine design applications. Computer-aided design (CAD) of these types of fasteners and permanent joining are made accessible to support the synthesis and optimization of some of these components and tools. The coverage is geared toward the applications in machine design to develop a good selection of the appropriate joining of machine elements and components. Symbols and Abbreviations Symbols Quantity, Units (adopted) A b Cross-sectional area of solid unthreaded bolt A CS Stripping shear area of the collar A m Member or element area A T Thread tensile stress area A TS Thread-stripping shear area C R Carrying ratio share due to stiffness ratio d a Average major and minor bolt diameter d C Average major and minor collar diameters d m Major or nominal thread diameter d p Pitch diameter of thread d r Root or minor thread diameter d W Washer outer diameter d Wa Average washer contact diameter Symbols Quantity, Units (adopted) dx Element thickness dδ Element contraction E b Modulus of elasticity of bolt...
- Lawrence Martin, John Purkiss(Authors)
- 2017(Publication Date)
- CRC Press(Publisher)
...The shank of the bolt is at least 2 mm greater in diameter than the threaded portion of the bolt and the hole is only 0,15 mm greater than the shank diameter. This small tolerance necessitates the use of special methods to ensure that the holes align correctly. Foundation bolts, or holding down bolts, are used for connection structural elements to concrete pads or concrete foundations. Generally the bolts are cast into the concrete before erection of the steel work and thus require accurate setting out. Where uplift forces occur the bolts must be anchored by a washer plate. Most bolts used are Class 4.6 but higher strengths are available. Sometimes bolts are grouted in the holes during erection using epoxy resin. Rivets were used extensively in the past in the fabrication shop and on site. They were difficult and expensive to place but they resulted in a rigid connection because the hot rivet, after driving, expanded to fill the hole. Rivets have now been superseded by welding and bolts. There are five categories of Bolted Joints (Table 3.2, EN 1993-1-8 (2005)) related to the type of connection or bolt and pre-loading. Shear connections Category A: bearing type where there is no pre-loading nor special provision for contact surfaces. Design for shear and bearing resistance. This is the cheapest type of connection where complete rigidity and plasticity are not important. Category B: slip resistant at serviceability limit state. Design for slip resistance at the serviceability limit state and shear and bearing resistance at the ultimate limit state. Connection used to provide full rigidity in the elastic stage of behaviour when deflections are critical. Category C: slip resistant at ultimate limit state. Design for slip resistance and bearing resistance at the ultimate limit state...
eBook - ePub- P.R. Knowles(Author)
- 2018(Publication Date)
- CRC Press(Publisher)
...The designer will then be able to keep in mind the underlying difficulties. It must be emphasised that good design considers all the elements, including connections, in a structure as a whole. Such an approach eliminates the problem of modifying members, already fully designed, in order to fit in connections. To list the requirements of a good connection in steelwork is not difficult. Ideally a connection should be: (a) rigid, to avoid fluctuating stresses which may cause fatigue failure (b) such that there is the least possible weakening of the parts to be joined (c) easily installed, inspected and maintained. The two practical connection types in current use are welds and bolts. Both have aspects which are departures from the ideal characteristics listed but both also have advantages in particular circumstances. 5.2 Bolts and bolting 5.2.1 Bolt types Peg fasteners of the rivet type are one of the oldest methods of joining metals; they can be traced back to man’s earliest use of ductile materials. For many years the riveted joint was the preferred method of connecting steel members. However, in recent years rivets have become much less popular for a variety of reasons amongst which economics must certainly figure. Riveting of structural steelwork is now unusual and so is not considered here. But the attributes of the rivet, a connection device which at reasonable cost produced a joint which was not prone to slip when subjected to pulsating load, are now available in the high strength friction grip bolt. Black bolts The term ‘black’ is applied to unfinished common or rough bolts which have not been finished to an accurate shank dimension. Black bolts are used where slip and vibration do not matter. They are supplied in mild or higher strength steel. Precision bolts For connections where slip and vibration are undesirable it is necessary to use accurately machined bolts fitted into precisely drilled holes...
eBook - ePub- John Dwight(Author)
- 1998(Publication Date)
- CRC Press(Publisher)
...CHAPTER 11 Joints This chapter considers the static strength (ultimate limit state) of aluminium connections, covering joints made with fasteners, welded joints and adhesive-bonded ones. The chapter should be read in conjunction with Chapter 3, which covered the technique of making such joints. 11.1 MECHANICAL JOINTS (NON-TORQUED) 11.1.1 Types of fastener In this section we look at the strength of aluminium joints made with ordinary fasteners, such as: aluminium rivets; aluminium bolts; stainless steel bolts; steel bolts. British Standard BS.8118 presents a range of materials from which such fasteners might be made. These are listed in Table 11.1, together with suggested limiting stress values for use in design. Other possible aluminium fastener materials are mentioned in Chapter 4 (Section 4.6). Aluminium rivets can be of conventional solid form. Alternatively, they may be of non-standard proprietary design, especially for use in blind joints (access to one side only). Rivets are not generally suitable for transmitting significant tensile forces. The bolts considered in this section are ‘non-torqued’, i.e. they are tightened without specific tension control. For joints loaded in shear, friction between the mating surfaces is ignored and the fasteners are assumed to transmit the load purely by ‘dowel action’ (shear and bearing). Bolts can be close-fitting or else used in clearance holes, the object of the former being to improve the stiffness of a joint in shear, though not necessarily its strength. Rivets or close-fitting bolts are essential for shear joints in which the transmitted load reverses direction in service, making it necessary to ream out the holes after assembly...
eBook - ePubStructures and Architecture - Bridging the Gap and Crossing Borders
Proceedings of the Fourth International Conference on Structures and Architecture (ICSA 2019), July 24-26, 2019, Lisbon, Portugal
- Paulo J.S. Cruz, Paulo J.S. Cruz(Authors)
- 2019(Publication Date)
- CRC Press(Publisher)
...A broad new field of applications in this case are the joints in offsite and modular construction (Sharafi et al. 2018, Lacey et al. 2018). The integration of fastenings – and construction products in general – to Building Information Modelling (BIM) is already ongoing (Lenz et al. 2019, Mahrenholz 2017), but the implementations as well as the Level of Details (LoD) still depend on project owner demands and building regulation requirements. Some novel technological applications which can be transferred to fastenings and assembly points include the integration of sensors (Spyridis et al. 2010, Hoepfner & Spyridis 2018), piezoelectric energy production (Huo et al. 2017), internet grid nodes for cloud networks (Psaras 2018), and assistance to as-built surveys and maintenance monitoring (Klein & Becerik-Gerber 2012, Lethola et al. 2017, Han & Golparvar-Fard, 2017). Within the current trends in building engineering and the interfaces between architecture and structural engineering, fastenings engineering and technology can be considered in the main perspectives of physical systematic integration, and of digital integration. 3.1 Physical integration of fastenings to structure – building – architecture interactions Based on the introduction and description of fastening performance requirements, and considering the increasing tendency for resource minimisation in the construction sector nowadays, it is self-evident that fastening products should simultaneously serve multiple functionalities. This is also further supported by the fact that fastening elements are manufactured items of high technical sophistication and precision. Also on the opposite side, a rapidly developing technology lies with the additive manufacturing, which can be the basis for customised connection solutions, serving each performance requirement for a very specific project or application...
eBook - ePubPractical Plant Failure Analysis
A Guide to Understanding Machinery Deterioration and Improving Equipment Reliability, Second Edition
- Neville W Sachs, P.E.(Authors)
- 2019(Publication Date)
- CRC Press(Publisher)
...Help you to diagnose fastener and Bolted Joint failures. How Bolts Work The idea of bolt elasticity is a critical one and a bolt acts a little like a very strong rubber band as it is being tightened. This stretching and the resultant clamping force then hold the parts together. In Figure 12.1, the sketch of a typical bolt includes the grip length which is important because it is the stretch in this area that provides the elasticity that does the clamping, the property critical to maintaining effective bolting performance. With equal loads, all grades of steel stretch the same amount and the benefit of going to a stronger bolt is that the elastic range of the steel is greater and the bolt can stretch more before it plastically deforms. Putting that into practice we see: (Remember, though, “There is no such thing as a free lunch”. The tradeoff for increased strength is increased susceptibility to damage from corrosion and reduced toughness.) With a conventional nut and bolt assembly, as it is tightened and the assembly develops this clamping force, some of the tightening work is absorbed by the stretching while the rest of it has to overcome friction, either between the rotating piece and the mating threads or between the rotating piece and its contact surface. Therefore, with better lubrication and less friction, more of the tightening torque can go into developing the clamping force. There have been many studies of this area and the current thought is that, on average, about 40% of the turning effort goes into overcoming thread friction, about 42% goes into overcoming friction between the rotating member face and the piece being clamped, while the remainder goes into stretching the bolt. Looking at the action of this clamping force, one sees that it is absolutely critical to effective performance. A good example is a bus or truck wheel...
eBook - ePub- Rikard Benton Heslehurst(Author)
- 2019(Publication Date)
- CRC Press(Publisher)
...Each repair scheme is basically one of the following (see Figure 6.2): FIGURE 6.2 Bolted and bonded joint configurations. • Doubler joint • Unsupported single-lap joint • Unsupported single-strap joint • Tapered unsupported single-strap joint • Double-lap joint • Double-strap joint • Tapered double-strap joint • Scarf joint (single and double) • Stepped-lap joint (single and double) Bonded vs. Bolted Joints Advantages and Disadvantages In joining processes and configurations for composite materials, there is a number of advantages and disadvantages. These advantages and disadvantages are listed in Table 6.1. Table 6.1 List of Advantages and Disadvantages in Composite Joint Types Joint Type Advantages Disadvantages MECHANICAL FASTENERS (Bolts, Rivets, Screws, Pins, Staples, etc.) Straight forward design Inspectable Repairable Any thickness Can be disassembled Many parts Stress concentration Relative weaker joint Fatigue prone Must seal the joint Prone to fretting Prone to corrosion ADHESIVE BONDING Few parts Full load transfer Repairable Fatigue resilient Sealing Stiff connection Light-weight structure Smooth contour Corrosion resistant No stress concentrations Difficult to inspect Surface preparation Environmental effects New design methods Trade skills required Thickness limited Residual stresses Cannot be disassembled Shear loading only Material Properties In joint design and for the repair of composite structures, the material properties of both the parent structure and the repair patch, plus the adhesive and fasteners, are. required. Parent Structure and Repair Patch An example of the properties for some typical metals used in repair and for two composite laminates in a quasi-isotropic configuration is given in Table 6.2...
