Bridge Substructure | Bridge Management Systems Flashcards
Commonly used criteria in selecting superstructure type:
- Bridge span
Which superstructure is perfered?
Flange
Prestressed Concrete Girder:
Timber Superstructures
Is less used than steel and concrete but they still maintain a niche in the highway bridge arena.
Disadvantages of Timber Superstructures
Exceedingly prone to deterioration.
Advantages of Timber Superstructures
*A high strength-to-weight ratio
+A replenishable material source
Secondary members attached between girders?
In the vertical plane that acts to stiffen the primary member and help distribute vertical loads.
Wearing Surface
Another work is wearing course or deck overlay.
Designed to resist traffic wear and, with periodic maintenance to provide smooth riding surface.
Function of wearing surface?
Protects the deck proper from traffic and the superstructure and substructure elements from associated deterioration.
Internal Forces
When a bridge is subject to loads, its constituent elements develop internal forces that resist those loads.
Form of Internal Forces
The resisting forces take the form of:
+Bending moment
*Shear Force
*Torsional moment
*Axial force
Abutments
Structures located at the ends of a bridge that provide the basic functions.
Basic Functions of Abutments
- Supporting the end of the first or last span.
- Retaining earth underneath and adjacent to the approach roadway.
- Supporting part of the approach roadway or approach slab, if necessary.
Types of Abutments
*Mechanically Stabilized Earth (MSE) Wall Abutment
*Gravity Abutments
*Cantilever Abutment
*Full-Height Abutment
*Stub Abutment
*Semistub Abutment
*U Abutment
*Counterfort Abutment
*Spill-Through Abutment
*Pile Bent Abutment
What is MSE
Utilizes modular facing units, generally made of unreinforced concrete, with metal or polymeric reinforcement (in the form of either strips or mesh) attached to the back.