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Bridge
Bridges provide passage over obstacles without blocking the way below. They carry traffic and loads over channels, roads, or railways. Bridges are classified based on their function, materials, form, position, construction method, and more. Common types include girder, truss, arch, cable-stayed, and suspension bridges, which vary in their typical spans and forces. Joints are often included to allow for movement from temperature changes and material shrinkage/expansion without compromising the bridge's integrity.
Bridge
- 3. A bridge isa structure providing passage over an obstacle without closing the way beneath. bridge is a structure for carrying the road traffic or other moving loads over a depression or obstruction such as channel, road or railway.
- 5. Function of ABridge
- 16. These are providedas extension of the abutments to retain the earth of approach bank which otherwise has a natural angle of repose.
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- 20. Classification of Bridges According to functions : aqueduct, viaduct, highway, pedestrian etc. According to materials of construction : reinforced concrete, prestressed concrete, steel, composite, timber etc. According to form of superstructure : slab, beam, truss, arch, suspension, cable-stayed etc. According to interspan relation : simple, continuous, cantilever. According to the position of the bridge floor relative to the superstructure : deck, through, half-through etc. According to method of construction : pin- connected, riveted, welded etc.
- 21. Classification of Bridges According to road level relative to highest flood level : high-level, submersible etc. According to method of clearance for navigation : movable-bascule, movable-swing, transporter According to span : short, medium, long, right, skew, curved. According to degree of redundancy : determinate, indeterminate According to type of service and duration of use : permanent, temporary bridge, military
- 22. According to theflexibility of superstructure: FIXED SPAN BRIDGES . MOVABLE SPAN BRIDGES.
- 29. Basic Types ofBridges Girder/Beam Bridge Truss Bridge Rigid Frame Bridge Arch Bridge Cable Stayed Bridge Suspension Bridge
- 30. Girder/Beam Bridge • Themost common and basic type • Typical spans : 10m to 200m
- 31. Truss Bridge • Trussis a simple skeletal structure. • Typical span lengths are 40m to 500m.
- 32. Forces in aTruss Bridge In design theory, the individual members of a simple truss are only subject to tension and compression and not bending forces. For most part, all the beams in a truss bridge are straight.
- 33. Arch Bridges Archesused a curved structure which provides a high resistance to bending forces. Both ends are fixed in the horizontal direction (no horizontal movement allowed in the bearings). Arches can only be used where ground is solid and stable. Hingeless arch is very stiff and suffers less deflection. Two-hinged arch uses hinged bearings which allow rotation and most commonly used for steel arches and very economical design. Hinge-less Arch Two hinged Arch
- 34. Arch Bridges Thethree-hinged arch adds an additional hinge at the top and suffers very little movement in either foundation, but experiences more deflection. Rarely used. The tied arch allows construction even if the ground is not solid enough to deal with horizontal forces. Three-hinged Arch Tied Arch
- 35. Forces in anArch Arches are well suited to the use of stone because they are subject to compression. Many ancient and well-known examples of stone arches still stand to this today.
- 36. Cable Stayed Atypical cable-stayed bridge is a continuous deck with one or more towers erected above piers in the middle of the span. Cables stretch down diagonally from the towers and support the deck. Typical spans 110m to 480m.
- 37. Cable Stay Towers Cablestayed bridges may be classified by the number of spans, number and type of towers, deck type, number and arrangement of cables.
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- 40. Suspension Bridge Atypical suspension bridge is a continuous deck with one or more towers erected above piers in the middle of span. The deck maybe of truss or box girder. Cables pass over the saddle which allows free sliding. At both ends large anchors are placed to hold the ends of the cables.
- 41. Forces in SuspensionBridge
- 52. ADVANTAGES Lightweight DISADANTAGES Noisy Unpleasant ride quality Possiblesafety issues Allows debris and salt laden water through TYPICALLY ONLY USED FOR REPLACEMENT IN KIND.
- 53. Full-depth grid wasintroduced by engineers in the 1930 s to speed up construction on large bridge projects Can be precast or cast-in-place for very quick installation; high performance to cost ratio High durability and longevity are demonstrated by the great service history FullyFILLED GRID SYSTEMS
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- 55. Partially filled grid– first used in the 1950 s to further reduce weight by eliminating concrete in bottom tension zone Can be precast or cast-in-place offering rapid construction; very good strength to weight ratio Proven performance, this LW system offers similar span capabilities to Full-Depth Half filled grid decks
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- 64. • Cooling andheating of decks causes deck contraction and expansion, respectively • When contraction is restrained, cracking can occur when the tensile stress exceeds the tensile strength • When expansion is restrained, distortion or crushing can occur • Joints are often specified to accommodate deck movements without compromising the structural integrity of the bridge
- 65. • Bridge deckjoints should protect the interior edges of concrete decks from vehicle loads, seal the joint openings, and accommodate movements resulting from temperature changes and creep and shrinkage of concrete • Joint failure is a internationwide problem in the • Failure is not necessarily caused by the joint material itself but also by careless design, improper installation, and inadequate maintenance
- 71. Accommodate lessthan 1- in. movements or minor rotations Are sometimes installed with armor angles to protect concrete slabs Are effective only under the assumption that the passage of water and debris through the opening will not have adverse effects on the supporting substructures
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Editor's Notes
- #43 1. In-situ reinforced concrete deck(most common type) 2. Pre-cast concrete deck(minimize the use of local labor) 3. Steel grid deck 4. Orthotropic steel deck 5. Timber deck
- #45 the major advantages is its relatively low costease of construction and extensive industry use
- #46 Precast concrete is a construction product produced by casting concrete in a reusable mold or "form" which is then cured in a controlled environment, transported to the construction site and lifted into place
- #47 By producing precast concrete in a controlled environment the precast concrete is afforded the opportunity to properly cure and be closely monitored by plant employees.The production process for Precast Concrete is performed on ground level, which helps with safety throughout a project. . There is a greater control of the quality of materials and workmanship in a precast plant rather than on a construction site. Financially, the forms used in a precast plant may be reused hundreds to thousands of times before they have to be replaced, which allows cost of formwork per unit to be lower than for site-cast production
- #48 1.Half filled grid decks2.Fully filled grid decks3.Exodermic Decks4.Open grid decks
- #61 This allows the deck both to directly bear vehicular loads and to contribute to the bridge structure's overall load-bearing behavior. The same is also true of the concrete slab in a composite girder bridge, but the steel orthotropic deck is considerably lighter, and therefore allows longer span bridges to be more efficiently designed.The Akashi-Kaikyō Bridge's orthotropic deck allowed the Japanese to build the longest span at about 6000 ft or 50% longer than the Golden Gate Bridge
- #63 Timber deck
- #65 Cooling and heating of decks causes deckcontraction and expansion, respectively• When contraction is restrained, cracking can occurwhen the tensile stress exceeds the tensile strength• When expansion is restrained, distortion or crushingcan occur• Joints are often specified to accommodate deckmovements without compromising the structuralintegrity of the bridge
- #79 Troughs