Introduction to Railway Bridges - PowerPoint Presentation

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Introduction to Railway Bridges

C.M.Gupta

.

Sr.Prof

. Br.2.

IRICEN

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Bridges

A

structure that is built over a river, road, or railway to allow people and vehicles to cross from one side to the

other.

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No. of Railway bridges

Important

Major

Minor

Total68011915132103144698

Over IR network, 36,470 (25.2 per cent) are over 100 year old of which 6,680 bridges are over 140 year old.14,324 bridges are 81 to 100 year old, 15,637 bridges are 61 to 80 year old. The balance 78,267 bridges are less than 60 years old.

As

on 01.04.17

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MAIN ELEMENT OF BRIDGES

1) Superstructure

Track Structure

Girder

Bearing2) Substructure Bed BlockTraining & Protective WorksPier/Abutment/Wing WallFoundations Monolithic Bridge like Pipe Culvert, Box Culvert and Arch act like one unit.

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CLASSIFICATION OF BRIDGES

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1. ACCORDING TO FUNCTION

1)Track Bridge (for rail vehicle)

Over water bodies

i.e

River/ Nallah /CanalOver Valley (viaduct)Over Railway (Fly-over)Over Road (RUB)2) Road Bridge (For Road Vehicle)Over Railway (ROB)

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3) Rail cum Road Bridge

Over river

4) Foot over Bridge (For pedestrian)

Over Railway (On platform for public)5) Pipe Line Bridge Over Railway6) Aquaduct - Canal or Nallah over Track

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2. ACCORDING TO MATERIAL OF CONSTRUCTION OF SUPER STRUCTURE

1)

Timber Bridge (obsolete)

2) Masonry Arch – Stone & BrickIn lime Mortar & Cement Mortar respectively3) Steel Bridge Riveted FabricationWelded Fabrication4) RCC Bridge5) Pre-stressed Concrete Bridge6) Composite (Steel & Concrete) Bridge

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3. ACCORDING TO FORM OR TYPE OF SUPERSTRUCTURE

1)

Pipe Culvert

2) RCC Slab3) Rail opening (Only on branch line)4) Rail Cluster (Only on branch line)5) RCC Box Culvert6) Steel Plate Girder7) Steel Open Web Girder8) Arch Bridge

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9) RCC/PSC ‘T” or “I” Beam Bridge

10) RCC/PSC Box Girder

11) Suspension Bridge

12) Cable Stayed Bridge

13) Bow String Bridge14) Moveable Bridge

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4. ACCORDING TO STRUCTURAL CHARACTERISTICS OF SUPER STRUCTURE

1) Simply supported

2) Continuous

3) Cantilever4) Balanced Cantilever5) Cable Stayed6) Suspension7) Rigid Frame.

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Arch Bridge

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Bowstring Bridge

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Cable Stayed Bridge

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Suspension Bridge

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Suspension Bridge

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Suspension Bridge: Forces

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RIGID FRAME

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5. ACCORDING TO LEVEL OF FLOOR SYSTEMS

1) Deck Type – (Track Structure on Top Flange or Chord)

2) Through Type (Track structure Floor System Connected to Bottom Chord Panel)

3) Semi Through Type (Track Structure Floor System Connected to Web and no top Bracings).

Plate Girder and Open web Girder

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SEMI THROUGH TRUSS

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PLATE GIRDER

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PLATE GIRDER

ELEVATION

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PLATE GIRDER

PLAN

CROSS

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PLATE GIRDER

CROSS SECTION

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Open Web Girder Bridges

Under Slung

Through Girder

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BOGIBEEL BRIDGE

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Through girder bridge

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Through girder bridge

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OPEN WEB THROUGH SPAN

ELEVATION

TOP CHORD

BOTTOM CHORD

VERTICALS

DIAGONALSEND RACKER

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TOP PLAN

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PLAN AT FLOOR LAVEL

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A truss is a simple structure whose members are subject to axial compression and tension only and but not bending moment.

T

he

most common truss types are Warren truss, Pratt truss and Howe truss.

Warren Truss Warren truss contains a series of isosceles triangles or equilateral triangles. To increase the span length of the truss bridge, verticals are added for Warren Truss.Pratt TrussPratt truss is characterized by having its diagonal members (except the end diagonals) slanted down towards the middle of the bridge span. Under such structural arrangement, when subject to external loads tension is induced in diagonal members while the vertical members tackle compressive forces. Hence, thinner and lighter steel or iron can be used as materials for diagonal members so that a more efficient structure can be enhanced.

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Howe Truss

The design of Howe truss is the opposite to that of Pratt truss in which the diagonal members are slanted in the direction opposite to that of Pratt truss (i.e. slanting away from the middle of bridge span) and as such compressive forces are generated in diagonal members.

Hence, it is not economical to use steel members to handle compressive force.

K-Truss

For heavy loads on a truss structure, the depth of the truss is intentionally made larger so as to increase the bending resistance and to reduce deflection. With the increase in length of the vertical struts, buckling may occur under vertical loads. Therefore, K-truss is designed in such as way that the vertical struts are supported by compression diagonals.

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Warren Trusses

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K-Truss

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Beam Bridge

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MOVEABLE BRIDGES :

Swing Bridge

Bascule Bridge

Lifting Bridge

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Bascule Bridges

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Swing Bridges

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Lifting bridges

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6. ACCORDING TO TYPE OF SERVICE

1) Permanent

2) Temporary

Restricted Head Girder (RH Girder)

Callender-Hamilton BridgePantoon Bridge

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Type of girder

Span

1.

Rail Cluster

3660mm (12’)2RH Girder(Plate girder type, duplicate girders) 1800mm

7200mm (24’) 9680mm(31’-9”) 13200mm (44”) 16400mm (53’-6”) 26480mm (87”)3.Calendar Hamilton Girder(open web through type) 24400mm (80’) 30500mm (100’) 45700mm (150’)

61000mm (200’)

4.

Standard Span

(Plate girders)

12200mm (40’)

18300mm (60’)

24400mm (80’)

TEMPORATY BRIDGES

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Pontoon Bridges 

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Title: Master

List of Drawings of Bridges &

Structures

Directorate, RDSO. BS-28(

Revision 21, version 1.7) MAY 2017

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7. ACCORDING TO METHOD OF CONNECTION (STEEL GIRDER)

1) Riveted

2) Welded

3) Bolted

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8. ACCORDING TO LEVEL OF DECKING WITH REFERENCE TO HFL

1) High Level bridge

2) Causeway or Irish Bridge

3) Siphon Bridge

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9. ACCORDING TO SPAN OR OPENING

1) Minor Bridge

Individual span < 12 m & Total Lineal Waterway< 18 m

2) Major Bridge

Individual span ≥12 M or Total Lineal Waterway ≥ 18 M3) Important Bridges –Total Lineal waterway 300 M OR Total Waterway 1000M2 OR Those classified as ‘IMPORTANT BY CE/CBE due to their depth of W.Way, Extent of River Training Works & Past History Maintenance Problem.

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10. ACCORDING TO RAILWAY GAUGE

1) Broad Gauge (BG – 1676 MM)

2) Metre Gauge (MG – 1000 MM)

3) Narrow Gauge (NG – 762 MM)

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11.

ACCORDING TO L

OADING

Broad Gauge

DFC25 TMBG – 1987 (Modified Broad Gauge)RBG – 1975 (Revised Broad Gauge)BGML (Main Line)BGBL (Branch Line)

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Thanks

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