Bridges are structures built to span physical obstacles without blocking passage underneath. The key components of bridges include foundations, abutments, piers, piles, girders, decks, and bearings. Foundations transmit loads from the rest of the bridge evenly to the soil or bedrock below. Piers and abutments support the superstructure of beams and decks that people or vehicles pass over.

2. INTRODUCTION
• A BRIDGE IS A STRUCTURE BUILT TO SPAN A PHYSICAL OBSTACLE, SUCH AS
A BODY OF WATER, VALLEY, OR ROAD, WITHOUT CLOSING THE WAY
UNDERNEATH.
• MOST LIKELY THE EARLIEST BRIDGES WERE FALLEN TREES AND STEPPING
STONES, WHILENEOLIYHIV PEOPLE BUILT BOARDWALK BRIDGES ACROSS
MARSHLAND.
• IT IS CONSTRUCTED FOR THE PURPOSE OF PROVIDING PASSAGE OVER THE
OBSTACLE, USUALLY SOMETHING THAT CAN BE DETRIMENTAL TO CROSS
OTHERWISE.

3. STRUCTURAL COMPONENTS OF BRIDGES

4. 1. COMPONENTS OF BRIDGES
1. FOUNDATION
2. ABUTEMENT
3. PIER
4. PILE CAP & PILE
5. GIRDER OR BEAM
6. DECKS
7. BEARING IN BRIDGES
8. WING WALL & THE RETURNS
9. PARAPET & HANDRAIL/ GUIRD RAILS/ CURB
10. BRIDGE ANCHOR

5. FOUNDATION
• WHICH HOLDS THE SHALLOW OR
DEEP BASE OF THE BRIDGE AND
TRANSFERS IT’S LOAD TO THE
BEARING STRATA, THIS INCLUDES
FOUNDATIONS BELOW THE MAIN
SPAN OF THE BRIDGE AND THE
ABUTMENTS BELOW STARTING
POINTS OF THE BRIDGE

6. • FOUNDATION ARE STRUCTURES CONSTRUCTED
TO TRANSMIT THE LOAD FROM THE PIERS,
ABUTMENTS, WING WALLS AND THE RETURNS
EVENLY ON THE STRATA.
• THE FOUNDATION PROVIDED FOR BRIDGE
STRUCTURES ARE DEEP IN SUFFICIENT MANNER
TO AVOID SCOURING DUE TO THE WATER
MOVEMENT OR TO REDUCE THE CHANCES OF
UNDERMINING.

7. ABUTMENT
• ABUTMENTS ARE VERTICAL STRUCTURES
USED TO RETAIN THE EARTH BEHIND
THE STRUCTURE. THE DEAD AND THE
LIVE LOADS FROM THE BRIDGE
SUPERSTRUCTURE IS SUPPORTED BY THE
BRIDGE ABUTMENTS.

8. ABUTMENT
• THE ABUTMENTS ARE ALSO SUBJECTED TO LATERAL PRESSURES MAINLY FROM THE
APPROACH EMBANKMENT. THE DESIGN LOADS ON THE ABUTMENT IS MAINLY
DEPENDENT ON THE: TYPE OF ABUTMENT SELECTED
THE SEQUENCE OF CONSTRUCTION
• THE SPECIAL CARE HAS TO BE PROVIDED FOR THE FOUNDATIONS OF ABUTMENTS. THE
ABUTMENT FOUNDATION MUST OVERCOME THE PROBLEMS OF DIFFERENTIAL
SETTLEMENT AND EXCESSIVE MOVEMENTS CAUSED DUE TO LATERAL FORCES OR
LOADS.

9. PIER
• THE PIERS ARE VERTICAL STRUCTURES USED TO
SUPPORT DECK OR THE BEARINGS PROVIDED
FOR LOAD TRANSMISSION TO UNDERGROUND
SOIL THROUGH FOUNDATION. THESE
STRUCTURES SERVE AS SUPPORTS FOR THE
BRIDGE SPANS AT INTERMEDIATE POINTS.
THE PIER STRUCTURE HAS MAINLY TWO
FUNCTIONS:
LOAD TRANSMISSION TO THE FOUNDATION
RESISTANCE TO THE HORIZONTAL FORCES

10. PIER
• TYPES OF PIERS IN BRIDGE CONSTRUCTION
• THERE ARE DIFFERENT TYPES OF PIERS BASED ON THE STRUCTURAL CONNECTIVITY, THE
SHAPE OF THE SECTION AND THE FRAMING CONFIGURATION.
• BASED ON THE STRUCTURAL CONNECTIVITY, THE PIER CAN BE CLASSIFIED
AS MONOLITHIC OR CANTILEVERED.
• BASED ON THE SHAPE OF THE SECTION PIER CAN BE CLASSIFIED AS SOLID OR
HEXAGONAL, ROUND OR OCTAGONAL OR RECTANGULAR.
• BASED ON THE FRAMING CONFIGURATION THE PIER CAN BE CLASSIFIED AS SINGLE OR
MULTIPLE COLUMN BENT, HAMMERHEAD OR PIER WALL TYPE.

11. PIER
• MOST OF THE CASES, PIERS ARE DESIGNED TO RESIST THE VERTICAL LOADS ALONE. IN
AREAS WHICH LIE IN THE SEISMIC ZONE, IT IS RECOMMENDED TO DESIGN THE PIER
FOR LATERAL LOADS ALSO.
• MOST OF THE PIERS ARE CONSTRUCTED USING CONCRETE. STEEL FOR THE
CONSTRUCTION OF PIER IS USED IN VERY FEW CASES TILL NOW. USE OF COMPOSITE
COLUMNS I.E. STEEL COLUMNS FILLED WITH CONCRETE IS USED AS NEW
TECHNOLOGY OF PIER CONSTRUCTION.
• THE PIER IS A VERTICAL MEMBER THAT RESIST THE FORCES BY MEANS OF SHEAR
MECHANISM. THESE FORCES ARE MAINLY LATERAL FORCES. THE PIER THAT CONSIST
OF MULTIPLE COLUMNS ARE CALLED AS BENT

12. PILE CAP & PILES
• PIER CAP IS THE TOPMOST PART OF
A PIER WHICH TRANSFERS LOADS
FROM 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.

13. • 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.
•

14. GIRDER OR BEAM
• BEAM OR GIRDER IS THE PART OF SUPERSTRUCTURE WHICH BENDS ALONG
THE SPAN. THE DECK IS SUPPORTED BY BEAMS.

15. DECKS
• THE DECKING IS CONSIDERED AS THE
ROAD OR THE RAIL SURFACE OF THE
BRIDGE. THE DECKS ARE SUPPORTED BY
THE GIRDERS OR THE HUGE BEAMS
THAT IS IN TURN SUPPORTED BY THE
PIERS. THE WHOLE ARRANGEMENT IS
SUPPORTED WITH A DEEP FOUNDATION
MAINLY PILES AND CAP ARRANGEMENT.

16. BEARING IN BRIDGES
• THE LOADS RECEIVED BY THE DECKS ARE
PROPERLY AND SAFELY TRANSMITTED TO THE
SUBSTRUCTURE WITH THE HELP OF BEARINGS.
THESE ARE COMPONENTS OF BRIDGE THAT
ENABLES EVEN DISTRIBUTION OF LOAD ON THE
SUBSTRUCTURE MATERIAL. THIS
TRANSMISSION IS VERY ESSENTIAL IN
SITUATIONS WHERE THE SUBSTRUCTURE IS
NOT DESIGNED TO TAKE THE LOAD ACTION
DIRECTLY.

17. • THE BEARINGS IN BRIDGES ALLOWS THE LONGITUDINAL MOVEMENT OF THE GIRDERS. THIS
MOVEMENT IS CREATED DUE TO THE FORCES ACTING ON THE LONGITUDINAL DIRECTION.
THE FORCES DUE TO THE MOVING LOADS AND THE VARIATION IN TEMPERATURE ARE THE
MAIN CAUSES FOR LONGITUDINAL FORCES.
• THE SELECTION OF BEARING IS DEPENDENT ON CERTAIN PARAMETERS, WHICH ARE: LOADS
ACTING, THE GEOMETRY, THE EXTENT OF MAINTENANCE, THE CLEARANCE AVAILABLE, THE
DISPLACEMENT, ROTATION AND DEFLECTION POLICY, AVAILABILITY, PREFERENCE OF THE
DESIGNER, THE CONSTRUCTION TOLERANCES, AND THE COST CRITERIA.
• FOR THE BRIDGE DESIGN, ALL THE ABOVE-MENTIONED ASPECT IS CONSIDERED FOR THE
DESIGN AND THE CHOICE OF BEARINGS. THE DESIGNER MUST CONSIDER THE BEARING
ARRANGEMENT IN THE BRIDGE CONSTRUCTION AS A SEPARATE SYSTEM.

18. WING WALL & THE RETURNS
• STRUCTURES CONSTRUCTED AS AN EXTENSION
OF THE ABUTMENTS TO RETAIN THE EARTH
PRESENT IN THE APPROACH BANK ARE CALLED
WING WALLS. THIS PORTION WILL OTHERWISE
HAVE A NATURAL ANGLE OF REPOSE. THESE
ARE RETAINING WALLS CONSTRUCTED
ADJACENT TO THE ABUTMENTS. THIS WALL
CAN BE CONSTRUCTED EITHER INTEGRALLY OR
INDEPENDENT WITH THE ABUTMENT WALL.

19. • THE REAR OF THE WALL MUST CONSIDER THREE DESIGN LOADS WHILE DESIGNING. THIS
INCLUDES:
• THE EARTH PRESSURE FROM THE BACKFILL
• THE SURCHARGE FROM THE LIVE LOADS OR THE COMPACTING PLANT
• THE HYDRAULIC LOADS FROM THE SATURATED SOIL CONDITIONS
• THE STABILITY OF THE WING WALL IS MAINLY BASED ON ITS RESISTANCE AGAINST THE
ACTIVE EARTH PRESSURES. THE STRUCTURAL ELEMENTS OF THE BRIDGES ARE HEREBY
DESIGNED AND CONSTRUCTED TO RESIST THE EARTH PRESSURES AT REST.

20. PARAPETS AND HANDRAILS/ GUARD RAILS
OR CURBS
• THESE COMPONENTS OF BRIDGES ARE
NOT OF STRUCTURAL IMPORTANCE, BUT
PROVIDED FOR THE SAFETY CONCERNS.
THESE ARE PROVIDED ABOVE THE
DECKS. THIS WILL HELP IN PREVENTION
OF THE VEHICLE FROM FALLING OFF THE
BRIDGE INTO THE WATER BODY BELOW
OR AS A MEANS FOR THE SEPARATION
OF TRAFFIC STREAMS.

21. BRIDGE ANCHOR
• BRIDGE ANCHOR IS ONLY USED IN
SUSPENSION AND CABLE-STAYED
BRIDGES TO RESIST THE PULL FROM
SUSPENSION CABLE OR COUNTER
SPAN OF THE BRIDGE