bridge
DESCRIPTION
TRANSCRIPT
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