Scour around Bridge Piers. Mohammad saeed khawam 201401379

Walid Omairi 201401485

Ayman Mansour 201400917

Basic Components of a BridgeThe two basic parts are:• Substructure - includes the piers, the abutments and the foundations.

• Superstructure - consists of the deck structure itself, which support the direct loads due to traffic and all the other permanent and variable leads to which the structure is subjected.• The connection between the substructure and the superstructure is usually made

through bearings. However, rigid connections between the piers (and sometimes the abutments) may be adopted, particularly in frame bridges with tall (flexible) piers.

Substructure : PiersPiers are of two basic types:

• Column piers - Concrete column piers may have a solid cross-section, or a box section may be the shape chosen for the cross-section for structural and aesthetic reasons.

• Wall piers - generally less economical and less pleasing from an aesthetic point of view. They are very often adopted in cases where particular conditions exist, e.g. piers in rivers with significant hydrodynamic actions or in bridges with tall piers where box sections are adopted.

Basic Types of Bridge Piers

Bridge scourBridge scour is the removal of sediment such as sand and rocks from around bridge abutments or piers. Scour, caused by swiftly moving water, can scoop out scour holes, compromising the integrity of a structure.In the United States, bridge scour is one of the three main causes of bridge failure

where 46 of 86 major bridge failures resultedfrom scour near piers from 1961 to 1976.

Some photos of bridges failed due to the scour of foundation material.

Effects of ScourLowering the river bed level around PierDestabilize the Foundation(Pier)

Piles exposed to river due to large scour

Mechanism of ScourDevelopment scour hole:Vortex system formed in front of the obstruction, and has the form of horseshoeRiver flow and boundary condition give riseto the energy of the vortex Increased shear stress commence local sediment transport

Local Scour at Piers• Occurs due to the acceleration of flow around the pier and the

formation of flow vortices.

A bridge in the dry season in Sudan

Shearing Stress Calculation

scourscour

scour

Protection : Gravel bags : put around pies used for filter function to reduce flow but disadvantages handling cost and potential damage to bags during installation and after a time loose rock due to flow

Rock Channel Protection at Bridges

Pier Scour Monitors (sonar) :

Thank you Mohammad saeed khawam ---Walid Omairi --- Ayman Mansour