SCHOOL OF CIVIL ENGINEERING

Bridge Engineering

2015-2016

Professor’s Name : Lei, Jun Qing

Student’s Name : CHINNY Lyheang

Student’s ID : 15129120

Homework1

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(1) The characteristics of Beam Bridge, arch bridge, cable-stayed bridge, and

suspension bridge are discussed.

Answer: The characteristic of bridge type:

- Beam Bridge: the beam bridge superstructure is a rigid structure that consist of one

horizontal beam supported at each end, usually by some kind of pillar or pier. And

it is composed of a concrete slab resting on a set of girders (beams) which could be

steel or precast-prestressed concrete beam. The set of beam and slab are formed a

frame structure to support traffic passes over the top of the slab. This type of bridge

provides three main advantages:

Design is simple for designer. It is simple design structure of beam and slab.

Beam bridge design is a uniform design which can be standardized easily.

Construction of Beam Bridge is relatively straightforward due to its

prefabricated primary members.

However, Beam Bridge is primarily designed for short to medium span length of

91m maximum span for steel beam and 49m maximum span for prestressed

concrete beam.

Figure 1: Beam Bridge

- Arch bridge: Arch bridge structure is a bridge with abutments (the point where the

2 structures or objects meet) at each end shaped as a curved arch. And it is a major

crossing structure which is composed of steel or prestress concrete arch structure

and steel or concrete frame deck. Generally, the deck is suspended by the vertical

cable (hanger) from the arch and for other design, the deck is supported by the short

column from the top of the arch structure. When the deck is supported on the top of

the arch, this is called a deck arch. When the deck is suspended from the arch, the

structure is called a through arch. The arch bridge is constructed for medium long

bridge with the span up to 300m.

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Figure 2: Arch Bridge

- Cable-stayed bridge: Cable-stayed bridge superstructure may be designed to be

supported at pylons (bearings), to be fixed at pylons or to be floating (no support at

pylons). To limit longitudinal sway movement, dampers were installed. The

maximum displacement at the expansion joint was controlled at 0.90m. If the

superstructure were fixed at the pylons, the foundation force due to earthquake

would become unmanageable. The significant number of modern bridges have the

span length from 153 to 1088m.

Figure 3: Cable-stayed Bridge

- Suspension bridge: Suspension bridge is one where cables (or ropes or chains) are

strung across the river (or whatever the obstacle happens to be) and the deck is

suspended from these cables. Modern suspension bridge has two tall towers through

with the cable are strung. The towers are supporting the majority of the roadway’s

weight. Suspension bridges use a box section roadway supported by high tensile

strength cables. Light, and strong, suspension bridge can span distance from 2,000

to 7,000 feet far longer than any other kind of bridge. They are ideal for covering

busy waterways.

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Figure 4: Suspension Bridge

(2) What are the bridge classification methods?

Answer: The bridges are classified by many methods according to its used material, its

serviceability function, or its design appearance.

- The bridge classified by its used material:

Wood bridge

Steel bridge

Prestress concrete bridge

Cable bridge

Glass bridge

- The bridge classified by its serviceability function:

Highway bridge

Railway bridge

City bridge

Pipe bridge

Pedestrian bridge

- The bridge classified by its design appearance:

Beam bridge

Suspension bridge

Self-anchored suspension bridge

Steel and concrete box girder bridge

Pre-stress concrete beam bridge

Steel or concrete arch bridge

Truss bridge

(3) What are the basic structure of the bridge?

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Answer: The bridge is composed of 3 main structures, superstructure, substructure and

appurtenances and site-related features, which is divided into some basic structures.

- Superstructure is all components of a bridge above the support. The basic

superstructure components consist of the following:

Wearing surface:

Deck:

Primary members:

Secondary members:

- Substructure consists of all elements required to support the superstructure and

overpass roadway. The basis substructure components consist of the following:

Abutments:

Piers:

Bearings:

Pedestals:

Stem:

Back wall:

Wing wall:

Footing:

Piles:

Sheeting:

- Appurtenance is any part of the bridge or bridge site that is not major structural

component yet serves some purpose in the overall functionally of the structure. The

major appurtenances and site-related features are as follow:

Embankment and slope protection:

Underdrain:

Approach:

Bridge railings and traffic barriers:

(4) The length of the bridge?

Answer: The length of the bridge is the length between the sidewalls of both abutments

of the bridge.

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Figure5: Length of bridge = 1970m

(5) Calculate the span

Answer: The span of bridge is the distance between the two bearing columns without

any intermediate bearing support.

Figure6: Span of bridge = 1280m

(6) Bridge height

Answer: The bridge height is the distance between the deck of the bridge and the lowest

water level or the distance between the deck of the upper bridge and the deck of the

lower bridge or the distance between the deck of the bridge and ground level.

Figure 7: H is the Bridge height

(7) Net height

H

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Answer: Net height is the clear vertical distance from the lowest point of the bottom of

the crown section of the bridge to the lowest point

Figure8: h is the Net height

h