Flashcards: CETS 2

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 physical obstacle, like:

If it carries road traffic or railway traffic or a pipe line over a channel or a valley:

If it carries the traffic or pipe over a communication system like roads or railways:

Bridge (several small spans) constructed over a busy locality, a valley, dry or wetland, or forming a flyover to carry the vehicular traffic:

Bridges of twisted vines and creepers were found in many parts of

Wooden bridges are some of the most ancient. Suspension bridges had been known in China as early as

the oldest surviving stone bridge in China is the

Zhaozhou Bridge is also historically significant as it is the

The ancient _______ were the greatest bridge builders of antiquity

They used cement, - called ______ consisting of water, lime, sand, and volcanic rock, which reduced the variation of strength found in natural stone

a major breakthrough in bridge technology came with the erection of the ______ in England during 1779,

is the portion that carries all the traffic.

The portion supports the deck slab and girder and connects one sub-structure to the other. That means all the elements of the bridge attached to a supporting system can be categorized as

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.

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.

is the part of the superstructure which bends along the span. The deck is supported by beams

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.

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 _____,____,_____,______, of the construction. Usually, bridge pier is constructed by in situ method with large panel formwork.

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.

is a device which supports the parts of superstructure and transfers loads and movements from the deck to the substructure and foundation.

is a slender member driven into the surrounding soil to resist the loads.

is a thick reinforced concrete slab cast on top of the group piles to distribute loads.

is only used in suspension and cable-stayed bridges to resist the pull from suspension cable or counter span of the bridge.

It is used in suspension and cable-stayed bridges for the hanging, supporting and counter balancing of the bridge deck.

Materials used in their construction

Various Structural Forms

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.

In addition to flexural stiffness and shear resistance, these bridges have sufficient torsional stiffness

• Oldest and most common bridge type known • Usually used for Short and Medium spans • Carry loads in Shear and Flexural bending

• 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, hence reduced deflections and rigid structure

•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 rocky banks. • Conventional curved arch rib has high Fabrication and Erection costs.

uses the pre-stressing principles but the pre-stressing tendons are exposed/outside of the beam

• The deck is hung from the cable by Hangers constructed of high strength ropes in tension • Cables are anchored at the abutment, hence abutment has to be massive

According to inter-span relations

According to position of bridge floor.

According to span length

According to Level of Crossing

According to Function

According to Utility

According to High Flood Level (HFL)

is a complicated place and a point where a suite of civil engineering disciplines converge to form one of the most exciting challenges in the profession.

A scan of the associated figure shows that a bridge designer must be concerned with:

is that portion of the deck cross section which resists traffic wear. In some instances this is a separate layer made of bituminous material, while in some other cases it is a integral part of concrete deck.

is the physical extension of the roadway across the obstruction to be bridged.

distribute loads longitudinally and are usually designed principally to resist flexure and shear.

are bracing between primary members designed to resist cross-sectional deformation of the superstructure frame and help distribute part of the vertical load between stringers. They are also used for the stability of the structure during construction

type of secondary member used to resist lateral deformation

are earth-retaining structures that support the superstructure and overpass roadway at the beginning and end of a bridge.

is a short column on an abutment or pier under a bearing that directly supports a superstructure primary member

is a primary component of the abutment supporting pedestals on top of a footing. Its main function is to transfer loads from superstructure to the foundation.

is the component of the abutment acting as a retaining structure on top of the stem. It also supports an approach slab, if there is one

is a side wall to the abutment backwall and stem designed to assist in confining earth behind the abutment.

As bearings transfer the superstructure loads to the substructure, so in turn do the abutment and pier footings transfer loads from the substructure to the subsoil or piles

When the soil under a footing cannot provide adequate support for the substructure (in terms of bearing capacity, overall stability, or settlement), support is obtained through the use of

In cofferdams or shallow excavation, the vertical planks which are driven into the ground to act as temporary retaining walls permitting excavation are known as

is any part of the bridge or bridge site that is not a major structural component yet serves some purpose in the overall functionality of the structure

The slope that tapers from the abutment to the underpass (embankment) is covered with a material called _______, which should both be aesthetically pleasing and provide for proper drainage and erosion contro

which is a drainage system made of perforated pipe or other suitable conduit that transports runoff away from the structure and into appropriate drainage channels (either natural or human-made).

The section of overpass roadway that leads up to and away from the bridge abutments is called the

are protective devices “used to shield motorists from obstacles or slope located along either side of roadway”

is the minimum distance between the structure and the underpass.

An analysis of a structure to compute the maximum allowable loads that can be carried across a bridge is called a

Permanent loads placed on a structure before the concrete slab hardens are called

are permanent loads placed on the structure after the concrete has hardened (e.g., bridge railing, sidewalks, wearing surface, etc.).

Temporary loads placed on the structure, such as vehicles, wind, pedestrians, etc., are called

A temporary box structure with only four sides (i.e., no top or bottom) that can be used as an earth support system in excavation for substructure foundations is called a

Construction that occurs in phases, usually to permit the flow of traffic through a construction site, is called

the bridge superstructure consists of a concrete slab resting on a set of girders, which are connected by diaphragms to form a frame.

For a very short span [less than 30 ft (9 m)] a one-way reinforced concrete slab supported on either end by small abutments is an economical structure.

When bending and torsion are major concerns, a box girder type of structure offers an aesthetically pleasing, albeit expensive, solution. Since these types of structures do not make use of standardized, prefabricated components, their role is usually restricted to major highway bridges that can take advantage of their ability to meet relatively long span requirements.

This type of bridge started to be built in the United States only 50 years ago, but the response has been overwhelming. Low cost, ease of construction, and aesthetics are the major reasons why this type of structure is now a popular choice for medium- and long-span bridges.

recognized as one of the consummate marvels of civil engineering.

is most often used for major crossings such as at the Hell Gate and Sydney Harbor bridges.

are encountered most often in historical engineering projects that require preservation or rehabilitation of existing structures