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Lecture 5- Cables.pptx. tension, loading effects
- 1. 1 5.1 GENERAL REMARKS 5.2CABLES SUBJECTED TO CONCENTRATED LOADS 5.3 CABLES SUBJECTED TO UNIFORMLY DISTRIBUTED LOADS 5.CABLES
- 2. 2 5.1 General Remarks Cables often form the main load-carrying element in many types of structures. In this chapter we will discuss some of the important aspects related to their structural analysis. Cables are mainly used in bridge construction. Examples of uses of cables are shown in the next slide.
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- 4. 4 5.1 Cable-Stayed Bridges SelanderBridge-Tanzania
- 5. 5 5.1 Suspension Bridges Suspension bridge needs to have very strong main cables.
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- 7. 7 5.2 Cables Cablesare often used in Engineering structures for support and to transmit loads from one member to another. When used to support suspension roofs, bridges, and trolley wheels, cables form the main load-carrying element in the structure. In the force analysis of such systems, the self weight of the cable may be neglected; however, when cables are used as guys for radio antennas, electrical transmission lines, and derricks, the cable weight may become important and must be included in the structural analysis. Cables are also used for prestressing in concrete beams.
- 8. 8 5.2 Cables…Cont’d Twocases will be considered in the structural analysis of cables; a cable subjected to concentrated loads and a cable subjected to a distributed load. When deriving the necessary relations between the force in the cable and its slope, we will make the assumptions that the cable is perfectly flexible and inextensible. Due to its flexibility, the cable offers no resistance to shear or bending and, therefore, the force acting in the cable is always tangent to the cable at points along its length.
- 9. 9 5.2 Cables…Cont’d Beinginextensible, the cable has a constant length both before and after the load is applied. As a result, once the load is applied, the geometry of the cable remains fixed, and the cable or a segment of it can be treated as a rigid body.
- 10. 10 5.2.1 Cable subjectedto concentrated loads
- 11. 11 5.2.1 Cable subjectedto concentrated loads
- 12. 12 5.2.1 Cable subjectedto concentrated loads
- 13. 13 5.2.1 Cable subjectedto concentrated loads Example 1: Determine the tension in each segment of the cable shown in the Fig. Also, what is the dimension h?
- 14. 14 5.2.2 Cable subjectedto a uniform distributed load Cables provide a very effective means of supporting the dead weight of girders or bridge decks having very long span. A suspension bridge is a typical example, in which the deck is suspended from the cable using a series of close and equally spaced hangers. See Fig in the next slide.
- 15. 15 5.2.2 Cable subjectedto a uniform distributed load A suspension bridge
- 16. 16 5.2.2 Cable subjectedto a uniform distributed load A suspension bridge
- 17. 17 5.2.2 Cable subjectedto a uniform distributed load…Cont’d
- 18. 18 5.2.2 Cable subjectedto a uniform distributed load…Cont’d Fig 5-3
- 19. 19 5.2.2 Cable subjectedto a uniform distributed load…Cont’d
- 20. 20 5.2.2 Cable subjectedto a uniform distributed load…Cont’d
- 21. 21 5.2.2 Cable subjectedto a uniform distributed load…Cont’d
- 22. 22 5.2.2 Cable subjectedto a uniform distributed load…Cont’d
- 23. 23 5.2.2 Cable subjectedto a uniform distributed load…Cont’d
- 24. 24 5.2.2 Cable subjectedto a uniform distributed load…Cont’d
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- 30. 30 5.2.2 Cable subjectedto a uniform distributed load…Cont’d Example 2: The cable in the Fig supports a girder that weighs 12kN/m. Determine the tension in the supporting cable at A, B, and C.