CETS463/464 Bridge Engineering PDF

CETS463 Professional Course- Specialized 2 (Construction Eng’g and Management BRIDGE ENGINEERING)  A bridge is a structure which is built over some physical obstacle...

CETS463 Professional Course- Specialized 2 (Construction Eng’g and Management BRIDGE ENGINEERING)  A bridge is a structure which is built over some physical obstacle such as a body of water, valley, or road, and its purpose is to provide crossing over that obstacle. It is built to be strong enough to safely support its own weight as well as the weight of anything that should pass over it. A bridge is a structure which maintains the communication over a 3 physical obstacle, like: P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d - over a channel/river, - over a road, E N G I N E E R I N G ) - over a railway line or - over a valley. C E T S 4 6 4 ( B R I D G E  If it carries road traffic or railway traffic or a pipe line over a channel or a valley: Bridge If it carries the traffic or pipe over 3 a communication system like P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d roads or railways: Fly-over/Over- Bridge Bridge (several small spans) E N G I N E E R I N G ) constructed over a busy locality, a valley, dry or wetland, or forming a flyover to carry the vehicular traffic: C E T S 4 6 4 ( B R I D G E Viaduct  Bridge is not a construction but it is a concept, the concept of crossing over large spans of land or huge masses of water, and to connect two far-off points, eventually reducing the distance between them. The bridge provides passage over the obstacle of small caverns, a valley, road, body of water, or other physical obstacle. The first bridges were believed to be made by nature — as simple as a log fallen across a stream. The first bridges made by humans were probably spans of wooden logs or planks and eventually stones, using a simple support 3 and crossbeam arrangement. P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d The first man-made bridges were tree trunks laid across streams in girder fashion, flat stones, and festoons of vegetation, twisted or braided and hung in suspension. These three types - beam, arch, and suspension - have been known and built since ancient times E N G I N E E R I N G ) and are the origins from which engineers and builders derived various combinations such as the truss, cantilever, cable-stayed, tied-arch, and moveable spans C E T S 4 6 4 ( B R I D G E  Bridges of twisted vines and creepers were found in many parts of India. Wooden bridges are some of the most ancient. Suspension bridges had been known in China as early as 206 BC. Chinese built big bridges of wooden construction, and later stone bridges, and the oldest surviving stone bridge in China is the Zhaozhou Bridge built around 605 AD during the Sui Dynasty. This bridge is also historically significant as it is the world's oldest open- stone segmental arch bridge. 3 P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d The ancient Romans were the greatest bridge builders of antiquity. They used cement, - called pozzolana consisting of water, lime, sand, and volcanic rock, which reduced the variation of strength found in natural stone. Though extremely versatile, wood has one obvious disadvantage and during the 18th century there were many innovations in the design and a major breakthrough in bridge technology came with the erection of E N G I N E E R I N G ) the Iron Bridge in Coalbrookdale in England during 1779, using cast iron for the first time as arches to cross the river Severn. With the Industrial Revolution, steel, which has a high tensile strength, replaced wrought iron for the construction of larger bridges to support large loads, and later welded structural bridges of various designs were C E T S 4 6 4 constructed. Bridges are classified as Beam bridges, Cantilever bridges, Arch bridges, ( B R I D G E Suspension bridges, Cable stayed bridges and Truss bridges.  The various parts and components of a bridge are as follows: 1.Deck 2.Superstructure 3.Substructure 4.Foundation 5.Girder or beam 3 P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d 6.Bridge tower 7.Pier 8.Pier cap 9.Bearings 10.Piles E N G I N E E R I N G ) 11.Pile cap 12.Bridge anchor 13.Suspension cable C E T S 4 6 4 ( B R I D G E  1. Deck Deck is the portion that carries all the traffic. 2. Superstructure The portion supports the deck slab and girder and connects one sub-structure to the other. That means 3 P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d all the elements of the bridge attached to a supporting system can be categorized as superstructure. 3. Sub-structure E N G I N E E R I N G ) The parts of the bridge which support the superstructure and transmit all the structural loads of the bridge to the foundations. For example, piers, abutments, etc. C E T S 4 6 4 ( B R I D G E  4. Foundation Foundation is the portion that transmits loads to the bearing strata. Foundation is required to support the piers, bridge towers, and portal frames. Generally, piles and well foundations such as H-pile, bore piles, pipe piles, or precast concrete piles are adopted. 5. Girder Or Beam 3 P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d The beam or girder is the part of the superstructure which bends along the span. The deck is supported by beams. 6. Bridge Tower E N G I N E E R I N G ) It is the vertical supporting part used for cable-stayed or suspension bridges. High-strength concrete and Insitu method are adopted to construct the bridge tower. C E T S 4 6 4 ( B R I D G E  7. Pier Pier is the part of the substructure that supports the superstructure and transfers loads of superstructure to the foundations. Pier is suitable for spanned bridges with a maximum width of deck up to 8 m (2 traffic lanes). The shape and size of the pier mainly depend on aesthetics, site, space, and economic constraints of the construction. Usually, bridge pier is constructed by in situ method with large panel formwork. 8. Pier Cap 3 P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d Pier cap is the topmost part of a pier that transfers loads from the superstructure to the pier. It is also known as headstock. It provides sufficient seating for the girders and distributes the loads from the bearings to the piers. 9. Bearings E N G I N E E R I N G ) Bearing is a device which supports the parts of superstructure and transfers loads and movements from the deck to the substructure and foundation. The main purpose of providing a bearing is to permit controlled C E T S 4 6 4 ( B R I D G E movement and decrease the stress involved.  10. Pile & Pile Cap Pile is a slender member driven into the surrounding soil to resist the loads. Pile cap is a thick reinforced concrete slab cast on top of the group piles to distribute loads. 11. Bridge Anchor Bridge anchor is only used in suspension and cable-stayed 3 P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d bridges to resist the pull from suspension cable or counter span of the bridge. 12. Suspension Cable It is used in suspension and cable-stayed bridges for the E N G I N E E R I N G ) hanging, supporting and counter balancing of the bridge deck. C E T S 4 6 4 ( B R I D G E C E T S 4 6 4 P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d 3 ( B R I D G E E N G I N E E R I N G ) General arrangement of Bridge C E T S 4 6 4 P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d 3 ( B R I D G E E N G I N E E R I N G ) Typical details of Abutment  Bridges are mainly classified according to: A. Materials used in their construction 3 P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d B. Various structural forms. E N G I N E E R I N G ) C. Construction and function. C E T S 4 6 4 ( B R I D G E C E T S 4 6 4 P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d 3 ( B R I D G E E N G I N E E R I N G ) STEEL TIMBER MASONRY CONCRETE (R.C.C or Pre-stressed) C E T S 4 6 4 P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d 3 ( B R I D G E E N G I N E E R I N G ) TIMBER Wooden bridge - Swedish Wood Bridge San Pedro-Cantiasay Wooden Foot C E T S 4 6 4 P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d 3 ( B R I D G E E N G I N E E R I N G ) MASONRY Longmen Bridge Spanish Bridge in the Philippines Malagonlong Bridge in Tayabas City: The Longest C E T S 4 6 4 P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d 3 ( B R I D G E E N G I N E E R I N G ) Marcelo Fernan Bridge CONCRETE (R.C.C or Pre-stressed) C E T S 4 6 4 P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d 3 ( B R I D G E E N G I N E E R I N G ) STEEL Quezon Bridge (Manila)  SLAB (0-12m) BEAM (10-30m) CANTILEVER/Balanced Cantilever (30-500m) Box-Girder (18-30m; 60-70m with Pre- stressing) 3 P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d (Cellular/Multi-celled Bridges) TRUSS (35- 300m) ARCH (20-500m) CABLE STAYED (90-350m) E N G I N E E R I N G ) SUSPENSION (300-2000m) C E T S 4 6 4 ( B R I D G E  SLAB Distinctive Features of Slab Bridges: Usually used for Short spans Carry loads in Shear and Flexural bending 3 Have sufficient torsional stiffness P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d Bearings are not required Simple Shattering/formwork is required Becomes heavy (increase in D.L) for large spans. Hollow slabs are sometimes provided for medium spans. E N G I N E E R I N G ) C E T S 4 6 4 ( B R I D G E  BEAM Distinctive Features of Beam/Girder Bridges: Oldest and most common bridge type known Usually used for Short and Medium spans 3 Carry loads in Shear and Flexural bending P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d In modern girder bridges, steel I-Beams replace Concrete Beams Low torsional stiffness E N G I N E E R I N G ) C E T S 4 6 4 ( B R I D G E  CANTILEVER/Balanced Cantilever A beam is said to be cantilevered when it projects outward, supported only at one end. A cantilever bridge is generally made with three spans, of which the outer spans are both anchored down at the shore and cantilever out over the channel to be crossed. The central 3 P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d span rests on the cantilevered arms extending from the outer spans; it carries vertical loads like a simply supported beam or a truss—that is, by tension forces in the lower chords and compression in the upper chords. The E N G I N E E R I N G ) cantilevers carry their loads by tension in the upper chords and compression in the lower ones. Inner towers carry those forces by compression to the foundation, and outer towers carry the forces by tension to the far C E T S 4 6 4 ( B R I D G E foundations.  Box-Girder Distinctive Features of Box Girder Bridges In addition to flexural stiffness and shear resistance, these bridges have sufficient 3 P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d torsional stiffness Most suitable for curved plan and longer span bridges E N G I N E E R I N G ) C E T S 4 6 4 ( B R I D G E  TRUSS Distinctive Features of Truss Bridge: The primary member forces are axial loads The open web system permits the use of a greater overall depth than for an equivalent solid web girder, 3 hence reduced deflections and rigid structure P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d Both these factors lead to economy in material and a reduced dead weight. The increased depth also leads to reduced deflections, that is, a more rigid structure. High maintenance and fabrication costs. E N G I N E E R I N G ) Aesthetic appearance is debatable mainly because of complexity of elevation. Used economically in the span range of upto 300m. C E T S 4 6 4 ( B R I D G E  ARCH Distinctive Features of Arch Bridge: Arch action reduces bending moments Economical as compared to equivalent straight simply supported Girder or Truss bridge Suitable; when site is a deep gorge with steep 3 P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d rocky banks. Conventional curved arch rib has high Fabrication and Erection costs. Unlike girders, can be built from stones Considered the most beautiful of bridge types E N G I N E E R I N G ) Used in the span range of up to 250m. C E T S 4 6 4 ( B R I D G E  CABLE STAYED Distinctive Features of Cable-Stayed Bridge: Cable-stayed bridge uses the pre-stressing principles but the pre-stressing tendons are exposed/outside of the beam All the forces are transferred from the deck 3 through the cables to the tower/pylon P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d Roadway deck can be: – (Prestressed) Concrete Box Deck – Steel Box Deck – Steel Truss Deck As compared with the stiffened suspension E N G I N E E R I N G ) bridge, the cables are straight rather than curved. As a result, the stiffness is greater The cables are anchored to the deck and cause compressive forces in the deck. C E T S 4 6 4 ( B R I D G E  Continuation……. All individual cables are shorter than full length of the superstructure. They are normally constructed of individual wire ropes, supplied complete with end fittings, 3 pre-stretched and not spun. P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d Aerodynamic stability has not been found to be a problem in structures to date. It is economical over 200-500m. E N G I N E E R I N G ) C E T S 4 6 4 ( B R I D G E  SUSPENSION Distinctive Features of Suspension Bridge: The deck is hung from the cable by Hangers constructed of high strength ropes in tension 3 Cables are anchored at the P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d abutment, hence abutment has to be massive The main cable is stiffened either by a pair of stiffening trusses or by a E N G I N E E R I N G ) system of girders at the deck level. This stiffening system serves to control the aerodynamic movements. C E T S 4 6 4 ( B R I D G E  Continuation……. Suspension bridge needs to have very strong main cables The complete structure can be erected without intermediate staging from the ground 3 P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d It is the only alternative for spans over 600m, and it is generally regarded as competitive for spans down to 3000m. E N G I N E E R I N G ) The height of the main towers can be a disadvantage in some areas; for example, within the approach road for C E T S 4 6 4 ( B R I D G E an airport C E T S 4 6 4 P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d 3 ( B R I D G E E N G I N E E R I N G ) Suitability on the basis of span  C-1): According to inter-span relations C-2): According to position of bridge floor. C-3): According to span length 3 P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d C-4): According to Level of Crossing C-5): According to Function C-6): According to Utility C-7): According to High Flood Level (HFL) E N G I N E E R I N G ) C E T S 4 6 4 ( B R I D G E  C-1): According to inter-span relations Simple bridge Continuous bridge Cantilever bridge Simple bridge Simple bridge is like simply supported beam type which consist two supports at its ends. For shorter spans, simple bridges are suitable. 3 P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d E N G I N E E R I N G ) C E T S 4 6 4 ( B R I D G E  Continuous bridge If the bridge span is very long, then we have to build more supports in between end supports. This type of bridge is termed as continuous bridge. Cantilever bridge 3 P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d Cantilever type of bridge have only supported at one end and another end is free to space. Generally, two cantilever portions are joined to make way to the vehicles or humans. E N G I N E E R I N G ) C E T S 4 6 4 ( B R I D G E  C-2): According to position of bridge floor. Deck bridge Through bridge Semi-through bridge Deck bridge In case of Deck Bridge, super structure or floor of bridge is positioned in between the high flood level and formation level. 3 P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d E N G I N E E R I N G ) C E T S 4 6 4 ( B R I D G E  Through bridge In case of through bridge, Super structure of bridge is completely above the formation level. Semi-through bridge 3 P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d If the super structure of bridge is partly above and partly below the formation level, then it is called as semi-through bridge. E N G I N E E R I N G ) C E T S 4 6 4 ( B R I D G E  C-3): According to span length Culvert bridge Minor bridge Major bridge Long span bridge Culvert bridge When the bridge span length is below 6meters then it is called as Culvert Bridge. 3 P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d Minor bridge If the bridge span length is in between 8 to 30 E N G I N E E R I N G ) meters, then it is called minor bridge. C E T S 4 6 4 ( B R I D G E  Major bridge For major bridge, the span is generally about 30 to 120 meters. 3 P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d Long span bridge When the span of bridge is more than 120 meters then it is termed as long span bridge. E N G I N E E R I N G ) C E T S 4 6 4 ( B R I D G E  C-4): According to Level of Crossing Over bridge Under bridge Over bridge To pass over another route (railway or highway), a bridge is constructed to allow traffic. This is called over bridge or fly over bridge. 3 P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d Under bridge If over bridge is not possible, an underground type bridge is constructed to pass another route. This is called under bridge. E N G I N E E R I N G ) C E T S 4 6 4 ( B R I D G E  Foot bridge C-5): According to Function Highway bridge Rail way bridge Aqueduct bridge Road cum railway bridge Foot bridge Foot Bridge is generally constructed for humans to cross the roads or rail route or any canal by foot. Vehicles are not allowed in this bridge. 3 P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d Highway bridge High way or road Way Bridge is used for road transportation. These are constructed over E N G I N E E R I N G ) rivers or another routes to allow road way traffic. Girder type bridges are used as highway bridges over rivers or canals. C E T S 4 6 4 ( B R I D G E  Rail way bridge Rail bridges are constructed for rail transportation. Truss type bridges are preferred for railways but how ever r.c.c bridges are also used. Aqueduct bridge Aqueduct bridges are nothing but water carrying bridges which 3 are constructed to0 transport water from source to system. P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d Road cum railway bridge This type of bridge is useful for both road way and railway E N G I N E E R I N G ) transport. It may be of one floor or two floors. If one floor is there then, rail and road way are arranged side by side. Otherwise roadway on top deck and railway in bottom deck is preferred. C E T S 4 6 4 ( B R I D G E  Temporary bridge C-6): According to Utility Permanent bridge Temporary bridge During construction of dams or bridges or during floods, temporary bridges are constructed at low cost for temporary usage. These bridges are maintained at low cost. After construction of original structure temporary bridges are 3 dismantled. Generally timber is used to construct temporary P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d bridges. Permanent bridge These bridges are constructed for long term use and maintained at high level. Steel or R.C.C bridges are come under this category. E N G I N E E R I N G ) C E T S 4 6 4 ( B R I D G E  C-7): According to High Flood Level (HFL) Low level bridge High level bridge Low level bridge The super structure of bridge is generally below high flood level. So, whenever floods occurred these are submersed in water. So, these are also called as submersible bridges. These are generally constructed for unimportant routes with low cost. 3 P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d High level bridge High level bridge is non submersible against floods. It is well E N G I N E E R I N G ) above the high flood level and constructed in important routes. C E T S 4 6 4 ( B R I D G E C E T S 4 6 4 P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d 3 ( B R I D G E E N G I N E E R I N G ) C E T S 4 6 4 P r o f e s s i o n a l C o u r s e - s p e c i a l i z e d 3 ( B R I D G E E N G I N E E R I N G )