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BRIDGE OVERVIEW
- 2. PRABHAT KUMARRAJPUT ROLL NO-131000150 CLASS ROLL NO-37 SECTION-A
- 3. FUNCTION OF A BRIDGE To connect two communities which are separated by streams, valley, railroads, etc.
- 4. TYPES OF BRIDGES Type by material of construction Type by use Type by structure Fixed or movable bridge
- 5. SPAN OF BRIDGE • Short span : 6-30m • Medium span: 30-100m • Long span: >100m • Span>6m: Bridge • Span<6m: Culvert
- 6. TYPE BY MATERIAL OF CONSTRUCTION • Stone bridges • Timber bridge • Reinforced concrete bridges • Prestressed concrete bridges • Steel bridge • Aluminium • Composite
- 7. TYPE BY USE • CarTraffic • Pedestrian • Double-decked. • Train bridges • Viaducts.
- 8. TYPE BY STRUCTURE • Arch bridge • Beam /Girder Bridge • Cantilever bridge • Truss • Tied arch bridges • Suspension • Cable stayed
- 9. Arch Bridge • These bridges uses arch as a main structural component (arch is always located below the bridge, never above it).They are made with one or more hinges, depending of what kind of load and stress forces they must endure. Typical span length 130 ft – 500 ft.
- 10. Very basic type of bridges that are supported by several beams of various shapes and sizes. Typically consists of a beam simply supported on each side by a support and can be made continuous later Inexpensive to build •Typical span length 30 to 650 ft Beam/Girder Bridge
- 11. Firth of Forth Bridge, Scotland 521m span Cantilever Bridge They support their load not through vertical bracing but through diagonal bracing.They often use truss formation both below and above the bridge.
- 12. All beams in a truss bridge are straight. Trusses are comprised of many small beams that together can support a large amount of weight and span great distances. Typical Span lengths: 40m- 500m Truss Bridge
- 13. Suspension Bridges Bridges that use ropes or cables from the vertical suspender to hold the weight of bridge deck and traffic.
- 14. Cable-stayed Bridge Bridge that uses deck cables that are directly connected to one or more vertical columns. Cables are usually connected to columns in two ways – harp design (each cable is attached to the different point of the column, creating harp like design of “strings” and fan design (all cables connect to one point at the top of the column).
- 15. Fixed or moveable bridges • Fixed – Majority of bridges are fixed, with no moveable parts to provide higher clearance for river/sea transport that is flowing below them.They are designed to stay where they are made to the point they are deemed unusable or demolished.
- 16. • Moveable – A movable bridge is a bridge that has dynamic moving parts used to change the form of the bridge, usually to allow passage for boats.There are many types of movable bridges, and they differ in the way they transform.
- 17. Basic SpanTypes Simple Span Continuous Span Cantilever Span
- 20. SITE SELECTION FOR BRIDGE a. A straight reach of the river. b. Steady river flow without cross currents: c. A narrow channel with firm banks d. Suitable high banks above high flood level on each side. e. Rock or other hard in erodible strata close to the river bed level. g. Absence of sharp curves in the approaches; h. Absence of expensive river training works; i. Avoidance of excessive underwater construction The characteristics of an ideal site for a bridge across a river are
- 21. CONSTRUCTION Some points that should keep in mind while designing the bridge- • Must carry own weight and weight of traffic • Must withstand force of high winds • Must consider effects of contraction and/or • Expansion due to temperature changes
- 22. • Permanent Loads: remain on the bridge for an extended period of time (self weight of the bridge) • Transient Loads: loads which are not permanent - gravity loads due to vehicular, railway and pedestrian traffic - lateral loads due to water and wind, ice floes, earthquake, etc. LOADS ON BRIDGES
- 23. VEHICULAR LOAD All road bridges in India are designed in accordance with “INDIAN ROAD CONGRESS” specifications. IRC:5-1998 , IRC:6-2000 {INDIAN ROAD CONGRESS}- • This model consist of- • Class AA loading • TrackedVehicle • WheeledVehicle • Class A loading • Class B loading
- 24. CLASS AA LOADING
- 25. CLASS A LOADING
- 26. CLASS B LOADING
- 27. LONGEST SPAN BRIDGE •Akashi kaikyo bridge Design Suspension bridge Total length 3,911 metres (12,831 ft; 2.430 mi) Height 282.8 metres (928 ft) (pylons) Longest span 1,991 metres (6,532 ft; 1.237 miles Clearance below 65.72 metres (215.6 ft)
- 28. LONGEST BRIDGE •Danyang–Kunshan Grand Bridge Total length 164.8 kilometres (102.4 mi) Carries Rail Locale China’s Jiangsu province
- 29. HEIGHEST BRIDGE •MillauViaduct Design Cable-stayed bridge Total length 2460 m Width 32.05 m Height 343 m (max pylon above ground) Longest span 342 m Number of spans 204 m, 6×342 m, 204 m Clearance below 270 m (890 ft)
Notas do Editor
- The arch has great natural strength. Thousands of years ago, Romans built arches out of stone. Today, most arch bridges are made of steel or concrete, and they can span up to 500m. This type can be further subdivided into those bridges in which the primary axial forces are compressive (arches) and those in which these forces are tensile (suspension bridges and cable-stayed bridges). Such forces normally have to be resisted by members carrying forces of the opposite sense. It must not be thought that flexure is immaterial in such structures. Certainly, in most suspension bridges, flexure of the stiffening girder (see Figure 2c) is not a primary loading in that overstress is unlikely to cause overall failure; however, in cable stayed bridges (particularly if the stays are widely spaced) flexure of the girder is a primary loading. Similarly, in arch bridges, non-uniform loading of the rib can cause primary bending moments to be developed in it and may well govern the arch design.
- By far the majority of bridges are of this type. The loads are transferred to the bearings and piers and hence to the ground by slabs or beams acting in flexure, i.e. the bridges obtain their load-carrying resistance from the ability of the slabs and beams to resist bending moments and shear forces. Only for the very shortest spans is it possible to adopt a slab without any form of beam. This type of bridge will thus be referred to generally as a girder bridge.
- Truss bridges are not specific bridge forms in themselves - rather trusses are used to perform the functions of specific members in one of the types above. For example, a girder in flexure or an arch rib in axial compression may be designed as a truss rather than as a solid web plate girder. A truss used as a girder in flexure carries its bending moments by developing axial loads in its chords, and its shears by developing axial loads in its web members. Definitions can become somewhat blurred, e.g, a tied arch can sometimes be considered to act as a truss girder, particularly if the hangers are inclined to form a triangulated system.
- Aesthetic, light, and strong, suspension bridges can span distances from305mto 1372m-- far longer than any other kind of bridge. They also tend to be the most expensive to build. True to its name, a suspension bridge suspends the roadway from huge main cables, which extend from one end of the bridge to the other. These cables rest on top of high towers and are secured at each end by anchorages. Forces In all suspension bridges, the roadway hangs from massive steel cables, which are draped over two towers and secured into solid concrete blocks, called anchorages, on both ends of the bridge. The cars push down on the roadway, but because the roadway is suspended, the cables transfer the load into compression in the two towers. The two towers support most of the bridge's weight. London Tower Bridge is 3 hinged suspension bridge. Tension member is a truss.
- Cable-stayed Bridge Cable-stayed bridges may look similar to suspensions bridges -- both have roadways that hang from cables and both have towers. But bridges support the load of the roadway in very different ways. The difference lies in how the cables are connected to the towers. In suspension bridges, the cables ride freely across the towers, transmitting the load to the anchorages at either end. In cable-stayeded bridges, the cables are attached to the towers, which alone bear the load.