bridge

PROJECT WORK ON PRAKASH NAGAR

BRIDGEBY

G.KIRANT.VAMSHI KRISHNAR.SANDEEPK.SRAVAN KUMARV.MADHU

A bridge is a structure providing passage over an

obstacle without closing the way beneath.

IN OTHER WORDSbridge is a structure for

carrying the road traffic or other moving loads over a depression or obstruction such as channel, road or

railway.

BRIDGE SPECIFICATIONS:The total bridge length from back to back

of backing walls is 332.74 m.Vent way: 20V of 16.00 M Foundations and substructure: Open

foundation in VRCC M20 grade concrete is proposed.

Abutments: Wall type abutments in VCC M15 with skin reinforcement 8mm dia

Piers: VRCC M20 & M25 circular piers of 2m dia.

Wing walls: Walls type wing walls are proposed in VCC M15 grade concrete with skin reinforcement of 8mm dia.

Hammer Head Bed Blocks over piers: VRCC M20 grade

Function of A BridgeA bridge has to carry a service

(which may be highway or railway traffic, a footpath, public utilities, etc.) over an obstacle (which may be another road or railway, a river, a valley, etc.) and to transfer the loads from the service to the foundations at ground level.

Components of bridge

SUPER STRUCTURE or DECKINGBEARINGSSUBSTRUCTUREPIERS AND ABUTMENTSWING WALLS AND RETURNSFOUNDATIONS

SUPERSTRUCTURE OR DECKING

This includes slab, girder, truss,

etc. This bears the load passing over it and transmits the forces

caused by the same to the substructures

BEARINGSThe BEARINGS transmit the load received from the decking on to the substructure and are provided for distribution of the load evenly over the substructure material which may not have sufficient bearing strength to bear the superstructure load directly

SUBSTRUCTURE

This comprises of Piers Abutments , Wing walls or return & their foundations.

Piers and Abutments:-These are vertical structures supporting deck/bearing provided for transmitting the load down to the bed/earth through foundation.

Wing walls and Returns: These are provided as

extension of the abutments to retain

the earth of approach bank

whichotherwise has a natural

angle of repose.

FOUNDATION

This is provided to transmit the load from the piers or abutments and wings or returns to and evenly distribute the load on to the strata

Open foundation (Raft or individual footings)Well foundations or pile foundations.

Here in this project the foundation is Open Foundation .

Materials for Construction

Classification of Bridges According to functions : aqueduct, viaduct, highway,

pedestrian etc. According to materials of construction : reinforced

concrete, prestressed concrete, steel, composite, timber etc.

According to form of superstructure : slab, beam, truss, arch, suspension, cable-stayed etc.

According to interspan relation : simple, continuous, cantilever.

According to the position of the bridge floor relative to the superstructure : deck, through, half-through etc.

According to method of construction : pin-connected, riveted, welded etc.

Classification of Bridges According to road level relative to highest

flood level : high-level, submersible etc. According to method of clearance for

navigation : movable-bascule, movable-swing, transporter

According to span : short, medium, long, right, skew, curved.

According to degree of redundancy : determinate, indeterminate

According to type of service and duration of use : permanent, temporary bridge, military

According to the flexibility of superstructure:FIXED SPAN BRIDGES .

MOVABLE SPAN BRIDGES.

A swing bridge is a movable bridge that has as its primary structural support a vertical locating pin and support ring, usually at or near to its centre of gravity, about which the turning span can then pivot horizontally

Swing bridge

A bascule bridge (sometimes referred to as a drawbridge) is a moveable bridge with a counterweight that continuously balances the span, or "leaf," throughout the entire upward swing in providing clearance for boat traffic.

Bascule bridge

A transporter bridge (also ferry bridge or aerial transfer bridge) is a type of movable bridge that carries a segment of roadway across a river.

Basic Types of BridgesGirder/Beam BridgeTruss BridgeRigid Frame BridgeArch BridgeCable Stayed BridgeSuspension Bridge

Girder/Beam Bridge• The most common and basic type

• Typical spans : 10m to 200m

Truss Bridge

• Truss is a simple skeletal structure.

• Typical span lengths are 40m to 500m.

Forces in a Truss Bridge

In design theory, the individual members of a simple truss are only subject to tension and compression and not bending forces. For most part, all the beams in a truss bridge are straight.

Arch BridgesArches used a curved

structure which provides a high resistance to bending forces.

Both ends are fixed in the horizontal direction (no horizontal movement allowed in the bearings).

Arches can only be used where ground is solid and stable.

Hingeless arch is very stiff and suffers less deflection.

Two-hinged arch uses hinged bearings which allow rotation and most commonly used for steel arches and very economical design.

Hinge-less Arch

Two hinged Arch

Arch BridgesThe three-hinged arch

adds an additional hinge at the top and suffers very little movement in either foundation, but experiences more deflection. Rarely used.

The tied arch allows construction even if the ground is not solid enough to deal with horizontal forces.

Three-hinged Arch

Tied Arch

Forces in an ArchArches are well

suited to the use of stone because they are subject to compression.

Many ancient and well-known examples of stone arches still stand to this today.

Cable Stayed

A typical cable-stayed bridge is a continuous deck with one or more towers erected above piers in the middle of the span.

Cables stretch down diagonally from the towers and support the deck. Typical spans 110m to 480m.

Cable Stay Towers

Cable stayed bridges may be classified by the number of spans, number and type of towers, deck type, number and arrangement of cables.

Cable Stay Arrangements

Cable Stayed Bridges

Suspension Bridge

A typical suspension bridge is a continuous deck with one or more towers erected above piers in the middle of span. The deck maybe of truss or box girder.

Cables pass over the saddle which allows free sliding.At both ends large anchors are placed to hold the

ends of the cables.

Forces in Suspension Bridge

BASIC TYPES OF BRIDGE DECKS

1. In-situ reinforced concrete deck(most common type)

2. Pre-cast concrete deck(minimize the use of local labor)

3. Steel grid deck

4. Orthotropic steel deck

5. Timber deck

In-situ reinforced concrete deck(most common type)

A cast-in-place concrete deck is a thin concrete slab, either using normal reinforcement or pre stressing steel

The thickness of these slabs is between 7 to 12 inches

A large cost of bridge maintenance is in

maintaining the riding surface.

Lack of deck crack control can lead to rebar

corrosion and increased life cycle cost, not to

mention a poor riding surface for the public.

Advantages

the major advantages is its relatively low

cost

ease of construction and extensive

industry useDis Advantages

Pre-cast concrete deck

Precast concrete is a construction product

produced by casting concrete in a reusable mold

 or "form" which is then cured in a controlled

environment, transported to the construction site

and lifted into place

Advantages

The production process for Precast Concrete is performed on ground level, which helps with safety throughout a project. . There is a greater control of the quality of materials and workmanship in a precast plant rather than on a construction site. Financially, the forms used in a precast plant may be reused hundreds to thousands of times before they have to be replaced, which allows cost of formwork per unit to be lower than for site-cast productionAnd also speed ups the construction

steel grid deck

1.Half filled grid decks

2.Fully filled grid

decks

3. Exodermic Decks

4.Open grid decks

When selecting a bridge deck, both initial costs and life-cycle costs should be consideredSteel grid bridge decks are time-tested, economical solutions for new or rehabilitated structuresMany grid reinforced concrete decks on structures with 50+ years of service:

South 10th St. Bridge (PADOT) 1932Jerome St. Bridge (PADOT) 1937-1980 sM. Harvey Taylor (PADOT) 1952-2001Walt Whitman (Del River Port Auth) 1956Mackinac (Mackinac Bridge Authority) 1957

WHY USE GRID DECKS?

Commonly used for lightweight deck on moveable bridges such as 17th St. Causeway Bridge in Ft. Lauderdale, FL(spanning floorbeams spaced @ 14.4 ft with no stringers)

OPEN GRID SYSTEMSFirst used in the 1920 s & is the oldest lightweightdeck systemIt is the lightest grid deck available, however spanlengths are limited

RECTANGULAR GRIDDIAGONAL GRID

ADVANTAGESLightweight

DISADANTAGESNoisyUnpleasant ride qualityPossible safety issuesAllows debris and salt laden water through

TYPICALLY ONLY USED FORREPLACEMENT IN KIND.

Full-depth grid was introduced by engineers in the 1930 s to speed up construction on large bridge projectsCan be precast or cast-in-place for very quick installation; high performance to cost ratio High durability and longevity are demonstrated by the great service history

FullyFILLED GRID SYSTEMS

FULL-DEPTH CONCRETE FILLED GRID

Partially filled grid – first used in the 1950 s to further reduce weight by eliminating concrete in bottom tension zoneCan be precast or cast-in-place offering rapid construction; verygood strength to weight ratioProven performance, this LW system offers similar span capabilities to Full-Depth

Half filled grid decks

PARTIAL-DEPTH CONCRETE FILLED GRID

DEVELOPED IN THE EARLY 1980 S EVOLVED FROM TRADITIONAL CONCRETE FILLED GRID DECKSAASHTO DEFINES AS UNFILLED STEEL GRID DECK COMPOSITE WITH A REINFORCED CONCRETE SLABTHROUGH OPTIMIZING THE MATERIAL PROPERTIES WHERE THEY BEST FIT, EXODERMIC DECKS HAVE THE BEST STRENGTH TO WEIGHT RATIO

EXODERMIC DECK

EXODERMIC DECK

Orthotropic steel deck

An orthotropic

bridge or orthotropic deck is one

whose deck typically comprises

a structural steel deck plate

stiffened either longitudinally or

transversely, or in both directions.

This allows the deck both to directly bear vehicular loads and to contribute to the bridge structure's overall load-bearing behavior. The same is also true of the concrete slab in a composite girder bridge, but the steel orthotropic deck is considerably lighter, and therefore allows longer span bridges to be more efficiently designed.The  Akashi-Kaikyō Bridge's orthotropic deck allowed the Japanese to build the longest span at about 6000 ft or 50% longer than the Golden Gate Bridge

Timber deck

EXPANSION JOINTS

INTRODUCTION• Cooling and heating of decks causes deck contraction and expansion, respectively• When contraction is restrained, cracking can occur when the tensile stress exceeds the tensile strength• When expansion is restrained, distortion or crushing can occur• Joints are often specified to accommodate deck movements without compromising the structural integrity of the bridge

• Bridge deck joints should protect the interior edges of concrete decks from vehicle loads, seal the joint openings, and accommodate movements resulting from temperature changes and creep and shrinkage of concrete• Joint failure is a internationwide problem in the • Failure is not necessarily caused by the joint material itself but also by careless design, improperinstallation, and inadequate maintenance

Problem: Incompressible Debris

Result: Failed Joint Seal

Consequences

• When joints fail, the integrity of the whole structure is affected!

Open Joints• Butt Joints• Sliding Plate Joints• Finger Joints

Closed Joints• Poured Seals• Asphalt Plug Joints• Compression Seals• Strip Seals• Reinforced Elastomeric Joints• Modular Elastomeric Joints

Open joints

Butt Joints

Accommodate less than 1- in. movements or minor rotations

Are sometimes installed with armor angles to protect

concrete slabs Are effective only under the assumption that

the passage of water and debris through the opening will not have adverse effects on the supporting substructures

Sliding Plate Joints• ACCOMMODATE MOVEMENTS BETWEEN 1 AND 3 IN.• ARE SIMILAR TO A BUTT JOINT EXCEPT THAT A PLATE IS ATTACHED TO ONE SIDE, EXTENDING ACROSS THE JOINT OPENING• PARTIALLY STOP DEBRIS FROM PASSING THROUGH OPENINGS• MAY BEND UNDER REPEATED TRAFFIC LOADS AND ARE SUSCEPTIBLE TO DEBRIS ACCUMULATION

Finger Joints• Accommodate movements greater than 3 in.• Are comprised of cantilevered fingers loosely interlocking each other over the opening• Are sometimes installed with drainage troughs to catch and channel away water anddebris• Can jam, bend, or break during service due tohorizontal and/or vertical misalignment duringconstruction

Closed joints

Troughs• Troughs should be designed with adequate

slope

• May require frequent flushing to prevent

debris

accumulation

• Accommodate movements up to 0.25 in.• Generally consist of viscous, adhesive, and pourable waterproof silicone installed with backer rods to prevent the sealant from flowing down the joint• Work best if sealant is poured when the ambienttemperature is at the middle of the historical temperature range

Poured Seals

•Accommodate movements less than 2 in.

• Are constructed by placing a modified elasto-plastic bituminous binder with mineral aggregate in a block-out centered over the joint, with a backer rod in place

• Can sustain damage when subjected to very rapidchanges in temperature

Asphalt Plug Joints

Accommodate movements less than 2½ in.– Are typically classifi ed as neoprene or cellular, both of which are installed using a lubricant that also serves as an adhesive agent– Should be sized in a working range of 40 to 85% of the uncompressed width to ensure that positive contact pressure isalways exerted against the face ofthe joint

COMPRESSION SEALS

Accommodate movements up to 4 in.• Consist of a flexible neoprene membrane attached to two opposing side rails• Can be susceptible to tearing, puncturing, or detachment under trafficking when debris accumulation rates are high• Normally exhibit long service life, very good anchorage, and high degree of watertightness

Strip Seals

– Accommodate movements between 2 and 6.5 in.– Are classified as sheet seals or plank seals– Are typically constructed using an epoxy bedding compound and cast-in-place studs– Are susceptible to leakage at locations of field splices and at interfaces between the seal and the underlying concrete

Reinforced Elastomeric Seals

• Accommodate movements between 4 and 24

in. and

up to 48 in. with special designs

• Consist of sealers, separator beams, and

support bars

• Are susceptible to fatigue damage and

leakage between compression seals and steel

supports

Modular Elastomeric Joints

Leveling of slabs

Levels for slab.Levels for carriage way.Levels for footpath or KERB leveling.

Levels for camber

CUBE TESTTO CALCULATE THE STRENGTH OF CONCRETE

STUDY OF SLAB DRAWINGS