Structural Analysis of Extradozed Bridge in Naluchi,Muzaffrabad

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Structural Analysis of Extradozed Bridge Naluchi ,Muzaffrabad

Misqal A Iqbal 2009-NUST-BE-CE-60

Abdul Haseeb Khan 2009-NUST-BE-CE-01

Ahad Aziz 2009-NUST-BE-CE-05

Hassan Cheema 2009-NUST-BE-CE-38

M Qasim Ali Waris 2009-NUST-BE-CE-90

Submitted to

Asst. Prof. Ammara Mubeen

Department of Structural Engineering

NUST Institute of Civil Engineering

School of Civil and Environmental Engineering

National University of Sciences and Technology

Islamabad, Pakistan

(2013)

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This is to certify that the report entitled

Structural Analysis of Extradozed Bridge Naluchi ,Muzaffrabad

Has been accepted towards the partial fulfillment of the requirements

for

Bachelor of Engineering

in

Civil Engineering

Asst. Prof. Ammara Mubeen

Department of Structural Engineering

NUST Institute of Civil Engineering

School of Civil and Environmental Engineering

National University of Sciences and Technology, Islamabad

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DEDICATED

TO

OUR PARENTS, TEACHERS AND COLLEAGUES.

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Acknowledgement

We are thankful to All Mighty Allah who gave us the strength and courage to accomplish this

project. We would like to express our foremost gratitude and sincere appreciation to our

advisor Mam Ammara Mubeen for providing invaluable support and dedicated encouragement

to us in our project. Her helpful suggestions, comments and advice are the impetus behind the

successful completion of this work. We are profoundly grateful to Dr. liaquat (Associate Dean

NICE) for their valuable guidance, suggestions and advice. We would especially like to thank Dr

Shahid Nasir (Consultant ) and Mam Shahzia and Mr Rizwan (Mastes student) for never ending

support, encouragement and for giving us access to data which proved to be of immense

importance for the completion of our project. In the end, we pay our earnest gratitude with a

sincere sense of respect to our parents for their unending support, encouragement, prayers

and patience.

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Abstract

Naluchi Extra dosed bridge project is a part of the transportation system of Muzaffarabad. The

bridge acts as an entrance into the capital city of the Province of Azad Kashmir. The new

extradosed bridge with its box girders will be the new landmark of the city. Extradozed

technology is related to girder bridges and cable stayed bridges.

The behavior of this Extradozed bridge is checked by modeling the bridge incorporating the

internal and external prestressing phenomenon in SAP 2000 and also in CSI Bridge. The effects

of the loads experienced by the bridge are studied in a narrow scope of Dead load analysis, Live

load analysis, Stage construction analysis, and Seismic analysis for expansion joints.

The moments, shear force along the bridge deck and support reactions at the piers and

abutments are computed and compared with the initial design report. These effects are also

computed without the stay cables being stressed.

The results of analysis were supported by the initial design report and hence our methodology

of modeling was affirmed by the results. The analysis gives an insight of the structural behavior

of each components of the bridge and hence gives us the input parameters for the design of

each component and the overall structural stability of the Bridge.

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Contents

Chapter 1 Introduction ........................................................................ 1

1.1 Introduction...................................................................................................................... 1

1.2 Objectives of Study: ......................................................................................................... 1

1.3 Scope of the Project ......................................................................................................... 2

1.4 Importance and location of Naluchi Bridge : .................................................................. 2

1.4.1 Location of Naluchi Bridge ....................................................................................... 4

1.4.2 Satellite image of Naluchi Bridge .............................................................................. 5

1.5 Components of the Bridge : ................................................................................................. 5

Chapter 2 Literature Review .................................................................. 7

2.1 Bridges .............................................................................................................................. 7

2.2 Classification of Bridges ................................................................................................... 7

2.2.1 Girder Bridges .......................................................................................................... 7

2.2.2 Arch Bridge ................................................................................................................ 8

2.2.3 Truss Bridge ............................................................................................................ 10

2.2.4. Suspension Bridge .................................................................................................. 11

2.2.5 Cable-Stayed Bridge ................................................................................................ 12

2.3 Extradosed Bridge Technology ...................................................................................... 13

2.3.1 History ..................................................................................................................... 13

2.3.2 Structural behavior ................................................................................................. 14

2.3.3 Design ...................................................................................................................... 14

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2.3.4 Extradosed Bridge Types ......................................................................................... 15

2.3.5 Stiffness of Superstructure and Substructure ........................................................ 18

2.3.6 Prestressing Methodology ...................................................................................... 20

2.3.7 Deck depth and mast height .................................................................................. 21

2.3.8 Length supported by cables .................................................................................... 22

2.3.9 Side span length ...................................................................................................... 22

Chapter 3 Structural Components of PC Extradosed Bridge, Naluchi ......................... 23

3.1. Substructure and Foundation of P3 Pier (Main Bridge) ................................................. 23

3.2. P3 Pier ............................................................................................................................ 24

3.2.1 Configuration of Deviator ....................................................................................... 24

3.2.2 Saddle ..................................................................................................................... 25

3.3 Stay Cable ....................................................................................................................... 26

3.3.1 Stay Cable Layout .................................................................................................... 26

3.3.2 Selection of Cable ................................................................................................... 27

3.3 Anchorage of Stay Cable ................................................................................................ 27

3.4.1 Stay Cable Anchorage ............................................................................................. 27

3.4.2 Wind Vibration ........................................................................................................ 28

3.5 Prestressed Concrete Girder .......................................................................................... 29

3.5.1 Number of Cells ...................................................................................................... 29

3.5.2 Dimension of girder ................................................................................................ 29

3.5.3 Arrangement of Inner Cables .................................................................................. 29

3.6 Specifications.................................................................................................................. 30

3.7 Materials ........................................................................................................................ 30

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3.7.1 Concrete: ................................................................................................................ 30

3.7.2 Reinforcing Steel .................................................................................................... 30

3.7.3 Prestressing Steel (Strand): ..................................................................................... 30

3.7.4 Support Stiffness’s of Naluchi Bridge:..................................................................... 31

3.8 Design Loads ................................................................................................................... 31

3.8.1 Construction Loads ................................................................................................. 31

3.8.2 Dead Load And Superimposed Dead Load : ............................................................ 31

3.8.3 Creep And Shrinkage : ........................................................................................... 31

3.8.4 Prestressing force: ................................................................................................. 32

3.8.5 Live Load ................................................................................................................. 32

Chapter 4 Structural Analysis of Naluchi Bridge .......................................... 33

4.1 Modeling Discretization ................................................................................................. 33

4.2 Elastic Analysis: .............................................................................................................. 33

4.3 Static Analysis: ................................................................................................................ 34

4.4 Methodology of modeling in SAP 2000: ........................................................................ 34

4.5 Naluchi Bridge Model: .................................................................................................... 36

4.5.1 Geometry Description ............................................................................................. 36

4.5.2 Imaginary Diaphragm Modeling ............................................................................. 37

4.5.3 Stay Cables Modeling .............................................................................................. 37

4.5.4 P2, P3 and P4 Pier modeling ................................................................................... 37

4.5.5 Loading Description ................................................................................................ 38

4.6 Dead load Analysis Results ............................................................................................. 39

4.6.1 Flexural Moments along the Deck (M 3-3): ............................................................ 39

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4.6.2 Shear Force Diagram: .............................................................................................. 40

4.7 Moving Load Analysis results: ........................................................................................ 40

4.8 Dead Load and Live Load Analysis Results : .................................................................. 41

4.8.1 Moment along the deck: ......................................................................................... 41

4.8.2 Shear along the Deck: ............................................................................................. 42

4.9 Dead Load, Live Load and Prestressing: ......................................................................... 43

4.9.1 Moment along the Deck: ........................................................................................ 43

4.9.2 Axial Force: .............................................................................................................. 43

4.10 Analysis Results in Tabular Form ................................................................................ 44

4.10.1 Dead Load Analysis ................................................................................................. 44

4.10.2 Dead and Live Load Analysis Results .................................................................... 51

4.12 Stage Construction Analysis: ...................................................................................... 53

4.12.1 Creep Stresses in Concrete ..................................................................................... 53

4.13 Seismic Analysis for Expansion Joint Displacement : ................................................. 53

4.13.1 Linear Dynamic Analysis: ........................................................................................ 53

4.13.2 Time History Analysis .............................................................................................. 54

4.13.4 Result of Time History Analysis: .............................................................................. 54

REFRENCES: ......................................................................................................................... 63

APPENDIX A HS 20-44 Loading

APPENDIX B List of Extradosed Bridges

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Chapter 1 Introduction

1.1 Introduction

The Naluchi Bridge is a cable stayed bridge with span configuration is 123m + 123m. The depth

of deck cross section is from 3.5 m to 7.0m across the spans. The Cable Stayed Bridge spanning

123m+123m = 246m over piers P2, P3, P4, and P3 is over the Jhelum River. The cable stayed

bridge with 24 meter high pylons is supported by double plane stays and will be constructed as

a free cantilever from the pylon outwards. The width of the deck is 15.6m.

This project was to comprehend the basics of bridge analysis, study different approaches of

bridges analysis, design methods for extra-dozed bridge superstructure, Internal pre-stressing

phenomenon, external prestressing phenomenon, effect of selection of different deck sections

on Bridge behavior under Loads, types of connections b/w Bridge components and Analysis of

Naluchi Extra-dozed cable stayed bridge in specific in SAP 2000.

Firstly, the modeling of the bridge was done in SAP 2000 putting in all the dimensions and

properties of the material provided by Wiecons and GRC Contractors. After completing the

modeling of the bridge the bridge was analyzed for dead load, live load and creep & shrinkage

using different load combinations provided in the AASHTO LRFD Bridge Specifications.

1.2 Objectives of Study:

The objective of Project are as follow :

Structural analysis of PC Extradosed Bridge at West Bank Bypass Project at Naluchi,

Muzaffarabad

Project-specific design criteria regarding serviceability and safety, applicability of the

design standards regarding design loads and materials.

Study of Design approaches of Extradosed Bridge.

Effects of internal prestressing and external prestressing phenomenon (Stay Cables)

Analysis of Naluchi Extradosed cable stayed bridge in specific in SAP 2000

Checking the analysis results to be within the acceptable limits.

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Comparison of analysis results with that of design consultant.

1.3 Scope of the Project

We will learn to use different computer softwares for analyzing and designing the

Extradosed bridge.

This Project will help in learning how different geometric parameters such as tower

height, girder depth, and pier dimensions influence the structural behavior and

feasibility of the Extradosed design concept.

This Project will help in analyzing and determination of loads that govern the design of

an Extradosed bridge.

We will develop a sense of judgment over how each of the components of Extradosed

bridge affects its structural behavior.

The case study of Extradosed bridge will provide us with an in-depth summary of

Extradosed bridges constructed to date that shows the large variability and great

potential that exists within this form. This information is also useful as a starting point

for initial dimensioning of the overall structure and its components.

This Project will help us tell about the primary factors that define the design of an

Extradosed bridge, from where it fits into the realm of bridge types, to solutions for

critical details that must be worked out in the final design.

This project will provide enough detail on the designs undertaken to allow a practicing

engineer to understand the key design steps involved in designing an Extradosed bridge.

1.4 Importance and location of Naluchi Bridge :

Naluchi Bridge hold a vital importance. There are lot of bridges in Pakistan but in terms of its

load carrying mechanism i.e. Extradosed bridge and the cables used in it which is the longest

cables used in any bridge in Pakistan.

These things make it unique, not only because its first of its type in Pakistan ,but also it will

benefit a lot to the people of Muzaffarabad as it will save the precious time and the distance

which people have to cover due to non-availability of any direct route to the the city. According

to an estimate about 30 to 40 minutes will be saved by the completion of this bridge. Another

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benefit will be the traffic congestion during peak hours which usually cause delay in daily

activities will be avoided. This bridge is located on the Jhelum river which separates the

Muzaffarabad city into two halves.

The coordinates of the starting point of Bridge are N34.37369 & E 73.464325,

the coordinates of the ending point of Bridge are N34.340979 & E 73.46182

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1.4.1 Location of Naluchi Bridge

Neelum Valley Road

End point N

Chela Bandi Br i dg e

Neelum Valley

Figure 1.1i

Muzzafarabad City

Naluchi Bridge

Islamabad

Muzaffarabad

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1.4.2 Satellite image of Naluchi Bridge

This is Satellite image of Naluchi Bridge which is shown by red lines taken from the Google

Earth.

Figure 1.2- Satellite image of Naluchi Bridge ii

1.5 Components of the Bridge :

The components of naluchi Bridge are as follow which are Shown in Figure 1.3

1. Pier 3

2. Pylons

3. Deck section

4. Shinso foundation

5. Stay Cable

6. End Supports (Pier 2&4)

7. Saddle

8. Anchorage Block

9. Bridge Bearing

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Figure 1.3- Components of Naluchi Bridge

Pier 3

Shinso

Pier 2

Pier 4

Stay Cables

Pylons

Deck

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Chapter 2

Literature Review

2.1 Bridges

A bridge is a structure built to span physical obstacles such as a body of water, valley, or road,

for the purpose of providing passage over the obstacle. Designs of bridges vary depending on

the function of the bridge, the nature of the terrain where the bridge is constructed, the

material used to make it and the funds available to build it

2.2 Classification of Bridges

Bridges are classified on the basis of following parameters:

Figure 2.1-Classification of Bridges

We shall only discuss the Structural Classification of bridges i.e. Girder bridge, Arch bridge,

Suspension Bridge ,Cable stayed Bridges

2.2.1 Girder Bridges

A girder bridge, in general, is a bridge built of girders placed on bridge abutments and

foundation piers. In turn, a bridge deck is built on top of the girders in order to carry traffic.

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There are several different subtypes of girder bridges:

2.2.1.1 Rolled steel girder bridge

It is made of I-beams that are rolled into that shape at a steel mill.

2.2.1.2 Plate Girder Bridge

It is made out of (mostly) flat steel sections that are later welded or otherwise fabricated into

an I-beam shape.

2.2.1.3 Concrete Girder Bridge

It is made of concrete girders, again in an I-beam shape.

2.2.1.4 Box Girder Bridge

It is built from girders in a rectangular box shape instead of an I-beam shape.

2.2.2 Arch Bridge

An arch bridge is a bridge with abutments at each end shaped as a curved arch. Arch bridges

work by transferring the weight of the bridge and its loads partially into a horizontal thrust

restrained by the abutments at either side.

Figure 2.2- Arch bridge iii

2.2.2.1 Load Transfer Mechanism of an Arch:

Instead of pushing straight down, the load of an arch bridge is carried outward along the curve

of the arch to the supports at each end. The weight is transferred to the supports at either end.

These supports, called the abutments, carry the load and keep the ends of the bridge from

spreading out.

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Figure 2.3-Load on Arch

The load at the top of the key stone makes each stone on the arch of the bridge press on the

one next to it. This happens until the push is applied to the end supports or abutments, which

are embedded in the ground as shown in Figure 2.3

Figure 2.4-Reaction

The ground around the abutments is squeezed and pushes back on the abutments (Figure 2.4)

Figure 2.5- Reaction

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For every action there is an equal and opposite reaction. The ground which pushes back on the

abutments creates a resistance which is passed from stone to stone, until it is eventually

pushing on the key stone which is supporting the load (Figure 2.5)

2.2.3 Truss Bridge

A truss bridge is a bridge composed of connected elements (typically straight) which may be

stressed from tension, compression, or sometimes both in response to dynamic loads. Truss

bridges are one of the oldest types of modern bridges.

Figure 2.6- Typical truss members

The lateral members in the planes of the top and bottom chords resist wind loads and brace the

compression chords. Sway frames are thought to square the truss and increase its torsional

rigidity. End portals carry torsional loads resulting from uneven vertical loads and wind loads

into the bearings.

Load Transfer Mechanism of Truss:

Figure 2.7-Tension & compression in Truss iv

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The nature of a truss allows the analysis of the structure using a few assumptions and the

application of Newton's laws of motion according to the branch of physics known as statics. For

purposes of analysis, trusses are assumed to be pin jointed where the straight components

meet. This assumption means that members of the truss (chords, verticals and diagonals) will

act only in tension or compression. A more complex analysis is required where rigid joints

impose significant bending loads upon the elements.

Figure 2.8 (c=Compression ,t=Tension)

In the bridge illustrated vertical members are in tension, lower horizontal members in tension,

shear, and bending, outer diagonal and top members are in compression,. The central vertical

member stabilizes the upper compression member, preventing it from buckling. If the top

member is sufficiently stiff then this vertical element may be eliminated. If the lower chord (a

horizontal member of a truss) is sufficiently resistant to bending and shear, the outer vertical

elements may be eliminated, but with additional strength added to other members in

compensation. The ability to distribute the forces in various ways has led to a large variety of

truss bridge types. Some types may be more advantageous when wood is employed for

compression elements while other types may be easier to erect in particular site conditions, or

when the balance between labor, machinery and material costs have certain favorable

proportions.

2.2.4. Suspension Bridge

A suspension bridge is a type of bridge in which the deck (the load-bearing portion) is hung

below suspension cables on vertical suspenders. This type of bridge has cables suspended

between towers, plus vertical suspender cables that carry the weight of the deck below, upon

which traffic crosses.

This arrangement allows the deck to be level or to arc upward for additional clearance. Like

other suspension bridge types, this type often is constructed without false work. Load applied

to the bridge is transformed into a tension in these main cable

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Load Transfer Mechanism of Suspension Bridge:s

Figure 2.9 –Suspension Bridge & its Component v

The force of compression pushes down on the suspension bridge's deck, but because it is a

suspended roadway, the cables transfer the compression to the towers, which dissipate the

compression directly into the earth where they are firmly entrenched. The supporting cables,

running between the two anchorages, are the recipients of the tension forces The anchorages

are also under tension, but since they, like the towers, are held firmly to the earth, the tension

they experience is dissipated.

Almost all suspension bridges have, in addition to the cables, a supporting truss system beneath

the bridge deck (a deck truss).This helps to stiffen the deck and reduce the tendency of the

roadway to sway and ripple.

2.2.5 Cable-Stayed Bridge

A cable-stayed bridge is a bridge that consists of one or more columns (normally referred to as

towers or pylons), with cables supporting the bridge deck

Figure 2.10-Forces in Cable-Stayed Bridge vi

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2.3 Extradosed Bridge Technology

Extradosed bridges are relatively expensive and material inefficient. Almost any span that could

be bridged by an Extradosed bridge could be spanned more inexpensively with a continuous

girder, or more efficiently (but at even greater cost) with a cable-stayed. In most cases the

spans are short enough that the use of cables at all is an aesthetic rather than engineering-

necessitated choice. This does not imply that is a "bad" choice, since in some cases the

difference in cost and efficiency is small, and the Extradosed type is a very elegant form.

In structural perspective, main differences between cable stayed and Extradosed bridge types

are load participation ratio, which affects design aspect of cable members. Since cable stayed

bridge totally rely on their vertical load to cable members, Extradosed bridge usually rely their

load on only 20% to 50% to cable, and left portion is covered by girder which is more stiffer

than stiffening girder in cable stayed bridge. It's usual that main design constraint in cable

stayed bridge is fatigue of cable and anchorage system. In Extradosed bridge, fatigue is not a big

concern since live load usually create only small amount of stress variation in cable because of

stiffness ratio between cable and their girder. Cost wise, allowable stresses for cables in cable

stayed bridges are always smaller than Extradosed bridge types - in may design code because of

fatigue concern and types of anchor can be chosen for external tendon anchorage system in

Extradosed bridge rather than cable stayed bridge type which way more expensive. Generally,

Extradosed bridges do not require tension re-adjustment (tune-up) before service because its

cables act as external-tendons.

2.3.1 History

From 1994 to 2008, over fifty Extradosed bridges have been constructed worldwide, and the

preferred proportions and cable arrangements have evolved. While there are many articles

available on the design of specific Extradosed bridges, very little has been published on their

design from a general perspective

The idea of using stay cables to support a bridge has been around for a while, it was first

applied during 1800's in the UK (incorporated with suspension bridges), many of which had

failed due to insufficient resistance to wind pressure, unaccountability of secondary effects of

the forces (lack of understanding of the mechanics of such a bridge was also a reason). But in

the 1900's, several factors contributed to successful implementations: Better methods of

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structural analysis of statically indeterminate structures (via computers) development of

orthotropic steel decks High strength steels, new methods of fabrication and erection.

A box girder supports the deck so as to reduce buckling of the deck from high compressions,

twisting or torsion, and distribute among the stays non-uniform loads. Cables are made of high-

strength steel, usually encased in a plastic or steel covering that is filled with grout, a fine

grained form of concrete, for protection against corrosion.

2.3.2 Structural behavior

Since Extradosed bridges take part in an intermediate zone between prestressed bridges and

cable stayed bridges, their structural behavior may be similar to these kinds of typologies,

depending on design criteria adopted during the project stage. Generally a rigid deck

Extradosed bridge shall have a similar behavior to the pre stressed bridge´s, thus avoiding high

stress oscillations of stay cables and, consequently, avoiding fatigue conditions associated with

anchorages and tendons present in a slender deck Extradosed bridge, which behavior is quite

close to the cable-stayed bridge. Its construction demands the acquaintance of technologies

currently applied on straight course-prestressed concrete bridges and cable-stayed bridges,

which is generally developed by means of the consecutive cantilever method but counting with

the assistance of tension rods that are not placed on temporary, but on permanent basis.

2.3.3 Design

An Extradosed bridge may be designed under two approaches. There is wide freedom to

choose stiffness arrangement for cables and deck to bear live load. The first approach considers

an adequate stiffness arrangement among deck, cables and substructure, in such a way tension

variation on cables due to live load does not supersede standard limits on specifications and,

might be stressed at maximum possible.

The Extradosed bridge form allows the designer to select the distribution of live load between

the stay cables and the girder, by changing the stiffness ratio of these two elements. Ogawa

and Kasuga (1998)vii compare this to the choice a designer has when designing an arch as deck-

stiffened or arch-stiffened.

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2.3.4 Extradosed Bridge Types

Generally, the first approach corresponds to a stiff deck with fixed connection among mast,

deck and piers as originally used for the first Extradosed bridges

The second design approach consists of stiff masts and a deck bridge, which is attributed to a.

Menn, who in 1987 introduced some ideas about advantages involved in the use of stiff masts

in cable-stayed bridges. viii

In accordance with this approach, deck is designed as much slender as possible, so that live load

may be transmitted into piers, as a couple of axial strengths in cables and box-girder, similar to

those in cable-stayed bridges. This design produces high tension oscillation values in stay

cables, due to live load and therefore, such elements must be stressed at a lower level than the

first approach, thus providing a less effective use of such elements.

According to Mermigas (2008)ix , generally the approach for Extradosed stiff deck bridge

does not provide any significant advantage over the stiff mast approach, which capacity to

stand multiple piers on simple supports is higher

Few researches have been developed to define project criterion on Extradosed bridges, which

structural behavior is quite similar to cable-stayed bridges, hence there is a need to deepen

into this subject . However, main conclusions obtained from some researchers are presented

below. It is made quite clear that projects criteria introduced by researchers are based on

particular load conditions and allowable tension limits for each study or, in case of well-known

engineers from experience obtained from completed projects. Therefore such criterion should

not be regarded as a straight jacket when considering an Extradosed bridge design, which

would limit the engineer possibility to explore different configuration and materials. In short we

can classify in two Types of Extradosed bridge by design:

Stiff girder Extradosed bridge:

I. Span to depth ratio varies from 30 to 50.

II. The live load is carried through flexural behavior.

III. The stresses in the cables are less.

Stiff pier (tower) Extradosed bridge

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I. Span to depth ratio varies from 100 to 150.

II. The live load is carried by the axial force couple between stays and girder.

III. The stresses in the cables are high.

Typical Bending Moment of Stiff girder Extradosed bridge under Permanent Loads:

Figure 2.11- Bending Moment of Stiff girder Extradosed bridge x

The Bending Moment of stiif girder Extradosed bridge is similar to a Girder bridge as shown in

the Figure 2.11 .Negative moments are shown above the bridge deck (light blue in colour) and

positive moment are shown below the deck (dark blue in colour)

Typical Bending Moment of Stiff pier Extradosed bridge

The Bending Moment of Stiff Pier Extradosed bridge is different by the way there are local

moment in between the cables

Figure 2.12- Bending Moment of Stiff pier Extradosed bridge

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Thus there are two different approaches that have been taken in the design of Extradosed

bridges. The following examples of the Pearl Harbor Memorial Bridge that has a stiff deck, and

the Sunniberg Bridge that has a flexible deck, illustrate these two extremes.xi

For the concrete design of the Pearl Harbour Memorial Bridge (51 in Appendix B) to be

built in New Haven, Connecticut, the designers proportioned the girder section based on the

maximum depth available given the grade and navigational clearance constraints, as well as

transverse bending requirements. The girder was then dimensioned with the “maximum

desirable amount of internal longitudinal post tensioning” for the section . Extradosed tendons

were used to reduce the bending moment demand to meet the available moment resistance of

the box section.

For the design of the Sunniberg Bridge (10 in Appendix B) , Menn has used the same

approach as for the design of a cable-stayed bridge: a cable arrangement is selected, cables are

sized according to maximum load for the allowable cable stress, and the girder is designed to

resist the bending moment between cables under dead load, and compatibility moments under

live load, caused by the distribution of axles loads to several adjacent cables. Finally, the cross

section was checked for buckling at the pier under combined bending and axial compression in

the deck. This process resulted in a bridge that has a span to depth ratio of 127. For a 2 lane

bridge of 140 m main span, the cable mass required to support half of the 140 m main span was

43 tonnes, a mass of 49 kg/m² of the deck surface, more than double that of the Pearl Harbour

Memorial Bridge.

Most Extradosed bridges built to date lie somewhere between these two examples. In

addition, the approach spans could be cantilever constructed by varying the depth of the box

girder. In the main span, Extradosed tendons were added to extend the useable span of the box

girder while meeting navigational and glide path clearance requirements above and below the

bridge. Ogawa and Kasuga (1998) define an index β as the distribution of the live load to the

stay cables, and claims that this index also represents the stiffness ratio between stay cables

and girders. β =( Load carried by stay cables)/ (Total vertical load)xii

The boundary between Extradosed bridges and cable-stayed bridges is suggested to occur at β

= 0.30, corresponding to a live load stress range in the cables of around 50 MPa. In practice, the

distribution index is not easily determined since all common live load models consist of both a

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uniform lane load and point loads representing vehicle axles. The distribution index is higher for

point loads than for uniform loads, because the girder locally distributes the point load to

cables surrounding the point of loading, not to all cables in the span.

A typical Axial Force and Bending moment due to 9 KN/m uniform load across main span

Axial Force Diagram

Figure 2.13- Axial Force

Bending moment

Figure 2.14-Bending Moment (M max =9140 kNm)

2.3.5 Stiffness of Superstructure and Substructure

The girder, cables, and tower form the superstructure load resisting system. For all

Extradosed bridges considered in , the tower is fixed to the girder, but the superstructure is

fixed to the substructure (piers) in only half of the bridges. In bridges with side spans of less

than half of the main span, as is almost always the case for cable-stayed bridges, the tower can

be stabilized by backstay cables. Backstay cables will not be discussed in this section because

very few Extradosed bridges rely on backstay cables,

When the superstructure rests on simple supports at the piers (free in rotation), as

opposed to being embedded (fixed in rotation) at the piers, a live load in any one span causes

bending in the girder, which causes a downwards displacement in the loaded span and an

upwards displacement in the adjacent span(s)

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To resist the bending moment in the girder and control displacements, the girder alone must

have adequate bending resistance and stiffness. For these two conditions to be jointly met, a

certain section depth is required to provide stiffness to the system, since the cables simply

transfer the load in one span to the adjacent span(s). A tensile force in a cable due to a point

load in one span is distributed through the tower to multiple cables in the adjacent span.

In the case of a superstructure embedded at the piers, any rotation of the superstructure at

each pier will be partially restrained by the substructure. This will decrease the bending

moment in the girder due to live load, since some of the moment is resisted by the pier. The

corresponding displacements are also reduced.

Comparison between monolithic and released connnection at main piers Bending moment due

to 9 kN/m uniform load across main span

Monolithic Connection

Figure 2.15- Monolithic Connection

Mmin = -15300 kNm Mmax = 9140 kNm

Released Conection

Figure 2.16- Released Conection

Mmin = -10500 kNm Mmax = -8120 kNm

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2.3.6 Prestressing Methodology

From the previous two sections, we observe that there are two separate factors which

influence the magnitude of the bending moments in the girder due to live load. Firstly, the

relative stiffness of the cables and girder which affects the distribution of forces between these

two systems, and secondly the connection between the superstructure and the substructure,

which affects the moment distribution between the superstructure and the piers. Long-term

effects lead to changes in the magnitude and distribution of bending moments in the

Extradosed bridge, and warrant further discussion before explaining the prestressing

methodology for an Extradosed bridge.

Axial shortening of the girder due to creep and shrinkage will cause a decrease in the

cables’ pretensions that causes long term bending moments,xiii For a concrete cable supported

structure, it is always desirable to have no net bending moment in the girder under permanent

loads (a bending moment distribution in the girder equivalent to that of a continuous beam on

simple supports) to reduce creep-induced deflections and uncertainties in the deflections over

the lifetime of the structure. This is especially important for cable-stayed bridge with flexible

decks, where the live load moment is a much greater proportion of the total moment than

permanent moments. Undulating internal tendons are installed to exactly balance the self-

weight of the slab between anchorages, to eliminate any net moment under permanent loads.

This is sometimes referred to as centered forces under permanent loads and is the preferred

means of keeping geometrical nonlinear effects to a minimum under permanent loads

It is also desirable to have centered forces during construction, as creep deformations

will be accelerated due to the early age of the concrete. This is only possible with cable tensions

adjusted to balance the construction loads: the self-weight of the deck and the weight of the

construction equipment.

This creates an apparent contradiction, which is often solved by first stressing the cables

to balance construction loads, then prestressing the cables to balance the permanent loads,

after the superimposed load is applied to the continuous structure. This is efficient in terms of

limiting the bending moment in the deck at all stages but it requires a laborious prestressing

operation.

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2.3.7 Deck depth and mast height

Figure 2.17-Dimension Nomenclature of Extradosed bridgexiv

Mathivatxv proposed a constant depth deck, slender L/h from 30 and 35, a mast height so that

L/H is equal to 15. Komiya xvi suggested for pier embedded bridges: edge with 35 slenderness in

the pier support section and 55 in the main center span and, mast heights ranging from L/12

and L/8. Chio xvii proposes project criterion using an edge for the pier support edge of L/30 and

central span L/45, i.e. ha/hc equal to 1.5. He also recommends a mast height equal to L/10, so

that rods tension oscillations due to live load would be delimited by 80 MPa value. Dos Santos

xviiiproposed a steady deck height L/33 and mast height L/10,

Figure 2.18

In General

a) H~L/15toL/8 b) h~L/50toL/30 [2]

http://en.wikipedia.org/wiki/Extradosed_bridge#cite_note-Benaim2007-0

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2.3.8 Length supported by cables

Chio recommended that the first tension rod should be fixed between 0.18 and 0.25 from

center span. Such value differs from Mathivat, who suggested that the first tension rod should

be fixed at 0.1 from central span. According to Komiya xix the combined cost for Extradosed

cables and internal tension roads fixed at 0.14, 0.20 and 0.24 from central span, has a variation

of approximately 2% among them and, the most cost effective arrangement is the one

corresponding to the first fixed stay cable at 0.20 from main span.

2.3.9 Side span length

Akio Kasugaxx stated that due to the similar structural behavior of Extradosed bridges with

prestressed box-girder bridges, side spans length should be determined proportionally to them,

generally between 0.6 and 0.8 from main span length. However, Chio indicated that for an

Extradosed bridge with constant depth deck, the use of ratios (L1/L) higher than 0.60, produces

high deflections, strainer strengths and tension increases on deck in comparison to closer side

spans. According to Chio , side span length variation (L1) has relevant effects on deck flexural

moments in the side span, which decrease as long as ratio (L1/L) goes down.

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Chapter 3

Structural Components of PC Extradosed Bridge, Naluchi

PC Extradosed Bridge is composed of the following major structural components;

1. Prestressed concrete PC girder

2. Reinforced concrete deviator

3. Pier

4. Foundation: Shinso foundation

5. Stay cable

3.1. Substructure and Foundation of P3 Pier (Main Bridge)xxi

A comparative study was conducted by JICA (Japan International Cooperation Agency) to

consider two alternatives (the Shinso type foundation with a span of 120m and spread footing

foundation with a span of 128m) for the river pier foundation. Based on the study, the result

shows that the Shinso type foundation is preferable due to cost reduction and reliability under

seismic forces.

Figure 3.1-Shinso Foundationxxii

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Figure 3.1 shows the Shinso Foundation in construction phase. Shinso Foundation is protected

by a Coffer Dam which is built to protect to the Shinso Foundation during the Construction and

also to ensure its safety after the construction phase during its serviceability.

Shinso Foundation is Hollow and Pier 3 is Projected from its bottom.

Figure 3.2-Pier3 projecting From the Shinso Foundation

3.2. P3 Pier

3.2.1 Configuration of Deviator

Pier 3 is Octagonal in shape at the bottom and Rectangular in the top most section. Due to its

variation in shape with length it is constructed by Slip Farm technology .This section is chosen

because of its less construction cost, structural aspect, and minimum construction duration as

the most optimum solution.

Design Strength of 30 MPa and maximum permissible water-cement ratio of 0.50 and cover of

100 mm. According to the Building Code Requirements for Structural Concrete (ACI-318-05),

minimum required strength of pier concrete is 27 N/mm2 and maximum permissible water

cement ratio is 0.50 if the pier is partially under water during flood. Hence it satisfies the

durability requirement.

The deviator also called the pylon basically functions as a deviating support. The top level of

pylon of PC Extradosed Bridge is about 80m from the foundation and about 24 m from deck

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surface to top level. The shape of pylon as a tower on the river is determined by structural and

architectural aspects.

Figure 3.3 shows the Pier 3.

Figure 3.3-Pier 3

3.2.2 Saddle

Saddle support is type of support in which stay cable passes through the pylon in continuity. In

this support system, anchorages are not required at the pylon hence exposure to atmosphere is

not likely and thus it is selected for the project.

The structural characteristics of saddle support are:

1. No hollow space in the pylon (filled with concrete)

2. The stay cables pass through the pylon, and the tension in both sides of the cables will

be balanced.

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Figure 3.4 -Cables passing through Pylon

3.3 Stay Cable

3.3.1 Stay Cable Layout

In the Extradosed bridge, stay cables have two functions, one to minimize bending moment by

up lifting self weight of the girder and second to resist the forces developed due to live loads.

The pylon (deviator) height is an important parameter for determining the stay cable layout

because it controls the magnitude of negative moment. Another parameter to be considered is

the amount of PC tendons. This calculation is based on the necessary tensile force and the

stress range. The appropriate stay cable layout is determined by considering cost optimization

by alternate study for the pylon height (20-26m), which are 1) H=20m; H/L=1/11.9, 2) H=23m;

H/L=1/10.4, 3) H=26m; H/L=1/9.2. The results showed differences in the number of PC tendons

amongst the cases considered in comparative study.

The 7 inner cables near the support have 19 strands having diameter 15.2 mm while outer 7

cables have 27 strands having the same diameter 15.2 mm.

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Figure 3.5--Stay Cable Layoutxxiii

3.3.2 Selection of Cable

Originally, twisted PC strand were developed for the PC cable stayed bridges and also as inner

cables for the PC girders.

For almost all Extradosed bridges, twisted PC strands are applied.

Figure 3.6 – Twisted Cable Strands

3.3 Anchorage of Stay Cable

3.4.1 Stay Cable Anchorage

Stay cable anchorages are constructed in order to transfer the tension of stay cables to main

girders efficiently. Anchors are reinforced by either PC tendons or by reinforcing bars against

local stress caused by tension of the stay cables. Stay cable anchorage area is surrounded by

large tensile stress from the stay cables. The anchorage zone on the main girder is an important

structural component that supports the main girder. Therefore, these parts have to be

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reinforced by PC tendons or reinforcing bars against shear forces and the local stress which

occurs due to the tensioning force induced by stay cable.

Figure 3.7 – Stay Cable Anchorage

3.4.2 Wind Vibration

While designing stay cable and anchorages of Extradosed bridge, it is desirable to conform to

“Wind-Resistance Design Handbook for Highway Bridges” Japan Road Association. It is evident

that wind and moving vehicles cause vibrations of stay cables. The vibrations of stay cables

include nominal vibration and self-excited vibration. Nominal vibrations due to vortex excited

oscillation arise from winds of relatively low speed and create vibrations of constant amplitude.

If the stay cable is anchored by fixity, a lateral force arises repeatedly near the anchorage zone

of the stay cable.

The vibration due to moving vehicles is an irregular vibration. Considering this, stay cable

anchorages have to be a flexible structure which can sufficiently absorb the vibrations.

Additionally, the stay cable and stay cable anchorage must be water proof and received

sufficient rust-proofing treatment.

Also, at the anchorage area, it is desirable to install protection facilities at the surface of girder

deck to prevent damage to stay cables even if automobiles collide with it. Protection facilities,

which are buffers or vibration isolators or dampers, have to be provided.

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3.5 Prestressed Concrete Girder

3.5.1 Number of Cells

The highly rigid box girder is necessary as a girder type because it can accommodate longer

clear span, i.e.120 m or more for the PC Extradosed Bridge. A box type which is hung

transversally by both ends with stay cable is selected while considering the deck width of

13.3m.

While selecting box girders, there is a choice between a single cell or a 2-cell box girder. Though

single cell box girder is easy in construction and maintenance but two-cell box girder is

structurally more durable and rigid. Unlike the 2 cell girder, the prestress tendons and rebar

requirement in transverse direction in case of single cell box girder are proportionately

increased due to longer unsupported span of box girder. Hence, it is finally concluded that 2-

cell type is the most appropriate girder type in this case.

3.5.2 Dimension of girder

A 2-cell box girder has a sectional scheme consisting of upper and lower flanges and three

webs. In the cross-section, the upper and lower flanges occupy a large area, so the girder can

resist large compressive stresses due to bending moments. PC tendons or reinforcing bars

should be placed so as to resist bending moment, tensile stress and shear stress due to working

loads. On the other hand, the girder has large torsion stiffness and it is desirable due to

eccentric distribution of live loads.

3.5.3 Arrangement of Inner Cables

Resisting bending moment due to working load is accomplished by effective arrangement of

inner PC cables with appropriate eccentricity with respect to the centroidal axis of the box

girder section

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Figure 3.8 –Cable arrangement of slab

3.6 Specifications

Following Specifications were followed by the design Engineer for the Design Purposes,

however we have only used ‘’Standard Specifications for Highway Bridges”, 17th Edition,

AASHTO 2004

1. Standard Specifications for Highway Bridges”, 17th Edition, AASHTO 2004

2. Designing of Bridge on National Highways”, NHA-JULY/2006

3. Standardization of Bridge Superstructure” NHA-MARCH/2005

4. Pakistan Code of Practice for Highway Bridges, PEC, 1996

5. Specifications for Highway Design” Japan Road Association

3.7 Materials

Materials Strength and Properties to be used in the Construction of bridge are as follow

3.7.1 Concrete:

Deck & Pylon Ec = 33430 MPa, fc’ = 40 MPa

Abutments, Pilecaps, Footing Ec = 26430 MPa , fc’ = 24 MPa

Where fc’ is the specified compressive strength of concrete at 28 days

3.7.2 Reinforcing Steel

Reinforcing Steel conform to deformed and plain billet steel bars. ASSHTO M31 (ASTM A615)

GRADE 420 with minimum yield strength fy = 420 MPa and minimum tensile strength fpu = 620

MPa

3.7.3 Prestressing Steel (Strand):

The properties of steel used in cables and prestressing tendons are as follows and are used as

input parameters in SAP2000s

Ultimate Strength fs’ = 1860 MPa

Yield Strength fpy = 1670 MPa

Elastic Modulus of Strand Es = 195000 MPa

Allowable Jacking Stress fsj = 73.5% of Ultimate Strength

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Wobble coefficient k = 0.0007 m-1

Draw-in at anchorage 8 mm

3.7.4 Support Stiffness’s of Naluchi Bridge:

U1(X) U2(Y) U3(Z)

P2 Pier 5,280,000 5,620,000 110,000,000

P3 Pier 14,000,000 14,000,000 103,000,000

P4 Pier 2,170,000 2,170,000 71,700,000

Table 3.1xxiv

These stiffness are to be used in Dynamic Analysis.

3.8 Design Loads

3.8.1 Construction Loads

The construction loads considered is : Weight of form traveler =100 tons

3.8.2 Dead Load And Superimposed Dead Load :

The dead load shall consist of the weight of the entire structure, including the roadway,

sidewalks, car tracks, pipes, conduits, cables, and other public utility services.

Reinforced Concrete : 24.5 kN/m3

Superimposed dead load :

1. Barrier & Railing : 20.63kN/m (two sides)

2. Asphalt : 8.0 ~ 17.7cm = 33.85kN/m

3.8.3 Creep And Shrinkage :

Structural calculations shall take into account the time dependent effects on materials, i.e.

creep, shrinkage of concrete and prestressing losses (instantaneous and long term losses).

Software uses CEB-FIP 1990 Model Code. Relative humidity of ambient temperature RH =

70%.Creep coeffiecent calculated by Design engineers is 1.4

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3.8.4 Prestressing force:

Prestressing losses due to friction, creep, shrinkage, taken into account the construction stages

shall be considered in computation models. Prestressing force of 444 KN is applied in each

tendon

3.8.5 Live Load

The live load consist of the weight of the applied moving load of vehicles, cars and Pedestrians

We will use HS 20-44 as recommended by AASHTO and is available in SAP2000.

3.8.5.1 H Loading

The H loadings consist of a two-axle truck or the corresponding lane loading as illustrated in

Appendix B. The H loadings are designated H followed by a number indicating the gross wesight

in tons of the standard truck.

3.8.5.2 HS Loading

The HS loadings consist of a tractor truck with semitrailer or the corresponding lane load as

illustrated in Appendix A. The HS loadings are designated by the letters HS followed by a

number indicating the gross weight in tons of the tractor truck. The variable axle spacing has

been introduced in order that the spacing of axles may approximate more closely the tractor

trailers now in use. The variable spacing also provides a more satisfactory loading for

continuous spans, in that heavy axle loads may be so placed on adjoining spans as to produce

maximum negative moments.

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Chapter 4

Structural Analysis of Naluchi Bridge

Structural analysis is a process to analyze a structural system to predict its responses and

behaviors by using physical laws and mathematical equations. The main objective of structural

analysis is to determine internal forces, stresses and deformations of structures under various

load effects.

Structural modeling is a tool to establish three mathematical models,

(1) Structural model consisting of three basic components: structural members or components,

joints (nodes, connecting edges or surfaces), and boundary conditions (supports and

foundations)

(2) Material model

(3) Load model.

4.1 Modeling Discretization

Formulation of a mathematical model using discrete mathematical elements and their

connections and interactions to capture the prototype behavior is called Discretization. For this

purpose: a) Joints/Nodes are used to discretize elements and primary locations in structure at

which displacements are of interest. b) Elements are connected to each other at joints. c)

Masses, inertia, and loads are applied to elements and then transferred to joints.

4.2 Elastic Analysis:

Service and fatigue limit states should be analyzed as fully elastic, as should strength limit

states, except in the case of certain continuous girders where inelastic analysis is permitted,

inelastic redistribution of negative bending moment and stability investigationxxv When

modeling the elastic behavior of materials, the stiffness properties of concrete and composite

members shall be based upon cracked and/or uncracked sections consistent with the

anticipated behavior (LRFD 4.5.2.2, AASHTO 2007). A limited number of analytical studies have

been performed by Caltrans to determine effects of using gross and cracked moment of inertia.

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The specific studies yielded the following findings on prestressed concrete girders on concrete

columns:

1) Using Igs or Icr in the concrete columns do not significantly reduce or increase the

superstructure moment and shear demands for external vertical loads, but will significantly

affect the superstructure moment and shear demands from thermal and other lateral loads

.Using Icr in the columns can increase the superstructure deflection and camber calculations xxvi

Usually an elastic analysis is sufficient for strength-based analysis.

4.3 Static Analysis:

Static analysis mainly used for bridges under dead load, vehicular load, wind load and thermal

effects. The influence of plan geometry has an important role in static analysis xxvii.One should

pay attention to plan aspect ratio and structures curved in plan for static analysis.

4.4 Methodology of modeling in SAP 2000:

The following are the general steps to be defined for analyzing a structure using SAP2000/CSI:

1. Geometry (input nodes coordinates, define members and connections)

2. Boundary Conditions/ Joint Restraints (fixed, free, roller, pin or partially restrained with

a specified spring constant)

3. Material Property (Elastic Modulus, Poisson’s Ratio, Shear Modulus, damping data,

thermal properties and time-dependent properties such as creep and shrinkage)

4. Loads and Load cases

5. Stress-strain relationship

6. Perform analysis of the model based on analysis cases

In this section, we create a SAP2000/CSI model for the Example Bridge using the Bridge Wizard

(BrIM-Bridge Information Modeler). The Bridge Modeler has 13 modeling step processes which

are described below:

4.4.1 Layout line

The first step in creating a bridge object is to define highway layout lines using horizontal and

vertical curves. Layout lines are used as reference lines for defining the layout of bridge objects

and lanes in terms of stations, bearings and grades considering super elevations and skews.

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4.4.2 Deck Section

Various parametric bridge sections (Box Girders & Steel Composites) are available for use in

defining a bridge. User can specify different Cross Sections along Bridge length.

4.4.3 Abutment Definition

Abutment definitions specify the support conditions at the ends of the bridge. The user defined

support condition allows each six DOF at the abutment to be specified as fixed, free or partially

restrained with a specified spring constant. Those six Degrees of Freedom are: U1- Translation

Parallel to Abutment U2- Translation Normal to Abutment U3- Translation Vertical R1- Rotation

about Abutment R2- Rotation About Line Normal to Abutment R3- Rotation about Vertical For

Academy Bridge consider U2, R1 and R3 DOF directions to have a “Free” release type and other

DOF fixed.

4.4.4 Bent Definition

This part specifies the geometry and section properties of bent cap beam and bent cap columns

(single or multiple columns) and base support condition of the bent columns.

The base support condition for a bent column can be fixed, pinned or user defined as a

specified link/support property which allows six degrees of freedom.

4.4.5 Diaphragm Definition

Diaphragm definitions specify properties of vertical diaphragms that span transverse across the

bridge. Diaphragms are only applied to area objects and solid object models and not to spine

models. Steel diaphragm properties are only applicable to steel bridge sections.

4.4.6 Hinge Definition

Hinge definitions specify properties of hinges (expansion joints) and restrainers. After a hinge is

defined, it can be assigned to one or more spans in the bridge object

4.4.7 Parametric Variation Definition

Any parameter used in the parametric definition of the deck section can be specified to vary

such as bridge depth, thickness of the girders and slabs along the length of the bridge. The

variation may be linear, parabolic or circular.

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4.4.8 Bridge Object Definition

The main part of the Bridge Modeler is the Bridge Object Definition which includes defining

bridge span, deck section properties assigned to each span, abutment properties and skews,

bent properties and skews, hinge locations are assigned, super elevations are assigned and pre-

stress tendons are defined. Since we calculate the pre-stress jacking force from CTBridge, we

use option to input the Tendon Load force.

4.4.9 Update Linked Model

The update linked model command creates the SAP2000/CSI object-based model from the

bridge object definition. l. There are three options in the Update Linked Model including:

1. Update a Spine Model using Frame Objects

2. Update as Area Object Model

3. Update as Solid Object Model

4.4.10 Bridge Results & Output

Analysis result and outputs are in the form of

1. Influence Lines and Surfaces

2. Forces and Stresses Along and Across Bridge

3. Displacement Plots

4. Graphical and Tabulated Outputs

4.5 Naluchi Bridge Model:

4.5.1 Geometry Description

The bridge to be modeled is 246m long with two span. The deck is 15.6m wide and varies

linearly. It has two lanes 5m wide each. This is a T-shape girder and pier structure along with

deviators (pylon) from which stay cables are hanging the box girder deck.

After providing section geometry data, all the sectional properties of the can be formulated.

Using this information, the different sections of bridge are designed and for this purpose a

bridge model with non-prismatic segments is created.

To create a non-prismatic member, starting and ending section, the length of the segment and

how the properties were varied over the segment are specified. Non prismatic members may

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have any number of segments and are defined using starting and ending sections and the

segment properties may be varied in linear parabolic and cubic manner.

Non prismatic sections, these may be assigned to the line diagram of the bridge deck as per

drawings of the initial design in similar preposition and alignment.

4.5.2 Imaginary Diaphragm Modeling

The section for the imaginary diaphragm (rigid zone element) is defined by assigning it the high

moment of inertia values while keeping its mass and weight zero

4.5.3 Stay Cables Modeling

Stay cable section was defined by specifying the diameter of the stay cable selected, material,

number of linear segments and tension at the two ends.

The initial tension in stay cables could be applied properly when the cable element is applied.

However, by applying frame element is successfully used in the analysis and initial tension is

applied as strain in the frame element. Strain calculation is shown in the Table 4.1

Nos. of

Strand

Initial

Tensile

Force (kN)

Area

(mm2)

E Strain

ε= σ/ E

27S15.2 7,500 3,744.9 Constant 0.005

19S15.2 5,400 2,635.3 Constant 0.005

Table 4.1- Strain Calculationxxviii

4.5.4 P2, P3 and P4 Pier modeling

P2 and P4 are modeled for dead and live load analysis by assigning the node at P2 and P4

location as, the restraints according to “Initial Design Final Draft”. Non prismatic section for P3

Pier is defined as per drawings of Initial Design and a fixed support at its base is assigned to it.

Cross beams and deviators are also modeled after defining their sections according to the

drawings of Initial Design

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4.5.5 Loading Description

4.5.5.1 Dead Load:

Self Weight of the girder, anchorage load and surface load are included in the dead load case.

To incorporate the effect of initial tension in the cables, the strain produced due to initial

tension is calculated and is defined in another load case

Dead Load of material used are given in table 4.2

DEAD LOAD kN/m3

Reinforced

Concrete 24.5

Plain Concrete 23

Steel 77

Asphalt 22.5

Table 4.2- Dead Loadxxix

4.5.5.2 Superimposed Dead Load:

In addition to dead load, Super Imposed dead load are also taken in account which are as

follows

1. Surfacing Parapet 6.395 kN/m2 = 2.79

2. Foot way 3.920 kN/m2 = 7.84

3. Steel Railing 0.300 kN/m2 = 0.60

4. As. Footway 1.350 kN/m² ×1.5×= 4.05

5. As. Carriage 1.800 kN/m² ×9.7 = 17.46

6. Leveling Concrete 0.69~2.231 ÷1.46 KN/ m²×9.7 = 14.16

Total super Imposed Dead load = 48.84 KN/m

4.5.5.3 Anchorage Load

Anchorage of Stay Cable = 68.7 KN/Anchorage

4.5.5.4 Live Load:

To define a live load, firstly, layout lines are defined by using the layout line command in the

bridge module and the same layout lines are used for lane definition. Next Class A standard

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truck-train highway live loads for bridges, live load for footway are defined and then vehicle

classes are defined. Each vehicle is assigned a vehicle class. When lanes and vehicles are

defined the moving load analysis case is set up and vehicle classes with reference to lanes are

mentioned.

4.6 Dead load Analysis Results

Dead Load analysis when Stay cables are prestressed results are shown below.In all the figures

the negative axis is shown above and positive axis is at the bottom of the layout line.

4.6.1 Flexural Moments along the Deck (M 3-3):

Figure 4.1- Moment along the deck

The Moment diagram of Naluchi bridge is similar to the Stiff girder Extradosed bridge as

mentioned in the . the maximum negative moment came on the central support which is pier 3

. Maximum negative moment is 591,193 KN. While Maximum Positive Moment came near the

center of the unsupported span on both sides of Pier 3 due to its symmetrical in nature.

Maximum positive moment is 136,077 KN.

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At the point of stay cables anchorage there is a little shift in the positive moment on both the

sides , thus releasing the some part of moment in the girder to the cables .

4.6.2 Shear Force Diagram:

Shear Force variation in the deck can be seen in Figure 4.2

Figure 4.2- Shear Force Diagram

Shear force is maximum at the Pier 3 i.e 29,530 KN and is similar in values in both side of the

Pier 3 but opposite in direction i.e a point on the same distance from the pier on both sides

have same numerical value but opposite in sign.

4.7 Moving Load Analysis results:

Moving Load analysis is carried out with vehicle HS 20-44 as defined earlier. The result of

Moving Load is the Moment envelope which shows the Maximum positive and Maximum

negative Moment at each point along the deck as a result of moing vehicles at the different

points because in actual conditions vehicles would be anywhere. When vehicle passes through

negative moment is created at that point and positive moment is created at different point .

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Figure 4.3- Moment envelope

The Moment envelope shows the maximum negative moment will be at pier 3 while there will

be no positive moment and the maximum negative moment will be near the center of the

unsupported span. It is same area where the dead load moment is maximum. But in addition to

the positive moment present here there is also the negative moment which is due to moving

vehicles.

4.8 Dead Load and Live Load Analysis Results :

The results shows the combination of Dead Load and Live Load.

4.8.1 Moment along the deck:

The Moment diagram of this combination is same as in the case of Dead Load because live Load

is less as compared to Dead Load and it adds up due to the fact that location of positive and

negative moments are same in both the cases.

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4.8.2 Shear along the Deck:

Similarly the Shear behavior is also the same as in Dead Load while the maximum shear in the

is 30.837 KN.

Figure 4.5- Shear Force Diagram

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4.9 Dead Load, Live Load and Prestressing:

The prestressing force is introduced in the Combination of Dead Load and Live Load and its

affect are studied .The Moment Diagram , Shear Force and Axial Force are discussed .

4.9.1 Moment along the Deck:

The Moment Variations is similar to the previous cases as in the shown in the figure 4.7


4.9.2 Axial Force:

The axial force shows the comparison in the Pier 3 where it is Maximum and at the point of stay

cable anchorage there is release of compression i.e. the cables are in tension the compression

is decreasing at that Point.

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Figure 4.7- Axial Force:

4.10 Analysis Results in Tabular Form

4.10.1 Dead Load Analysis

The comparison of result of Design , vetting consultant and analysis carried out by us are shown

in table. Analysis is done both by taking the affect of stay cables and without stay cables

4.10.1.1 Moment and Shear Results

The moment and shear result of Dead load are given below in table 4.3 and shown in graphical

form in Figure 4.7

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Table 4.3-Moment and Shear Result

The maximum positive moment and maximum negative moment can be compared by the

following graph

Figure 4.8-Maximum positive & negative

From the table 4.3 & figure 4.8 we infer that,

0

200000

400000

600000

800000

1000000

1200000

Max +Moment (KN-

m)

Max- Moment(KN-m)

Design Consultant

Vetting Consultant

Analysis With prestressedstay cables

Analysis W/OPrestressing in stay cables

ITEM

Design

Consultant

Vetting

Consultant

Analysis With

prestressed

stay cables

Analysis W/O

Prestressing in stay cables

Max positive

Moment (KN-

m)

36137 144128 136077 297241.55

Max negative

Moment (KN-

m)

685053 634031 591932 1135636

Max Shear (KN) 28395 30670 30874 39558.2

46 | P a g e

1. At pier 3 ( centrral pier ) there is negative moment due to the integrity of deck with the

pier

2. There is monolithic connection.

3. At start P2 abutment the moment are reduced to zero as there is an expansion joint at

P2 hence all moments are released/

4. At P4 pier the moments are also released due to expansion joint.

5. At P3 support the deck bears a high negative moment hence the tension is induced in

the top fibers of the girders near P3. For that the internal prestress tendons are to be

placed in the upper portion of the webs to cater for the tensile stresses.

6. As we move away from P3 the negative moments reduce and gradually become positive

at center span. The internal prestressing tendons profile also moves gradually to the

bottom of the webs to cater the tension in bottom fiber at positive moment sections.

4.10.1.2 P2 Support Reactions

The Pier 2 Reaction In tabular form

Table 4.4- P2 Support Reaction

The graphical display of P-2 Support reaction

P2 SUPPORT REACTIONS

ITEM

Design

Consultant

Vetting

Consultant

Analysis

With

prestressed

stay cables

Analysis W/O


Fx(KN) 0 0 0

0

Fz(K

N) 5776 7450.61 7295.46

14373.927

M(K

N-m) 0 0 0

0

47 | P a g e

Figure 4.9- P2 Support Reaction

Table 4.4 & Figure 4.10 shows the Support Reaction of Pier 2The last column of table 4.4 shows

the analysis result without Prestressing in stay cables which is very much larger due to the fact

more load is transferred through all three piers. While in case of prestressed cables the major

portion of load is carried through pier3 and minor portion to Pier 2 and Pier 4.

0

2000

4000

6000

8000

10000

12000

14000

16000

Fz(KN)

Design Consultant

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Analysis With prestressed staycables


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ITEM

Design

Consultant

Vetting

Consultant

Analysis With

prestressed stay

cables

Analysis W/O


Fx(KN) 0 0 0 0

Fz(KN) 172987 174026 179466 165106

M(KN-m) 280 9517 26337 1362.296




0

20000

40000

60000

80000

100000

120000

140000

160000

180000

200000

Fz(KN) M(KN-m)

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ITEM

Design

Consultant

Vetting

Consultant

Analysis With

prestressed stay

cables

Analysis W/O


Fx(KN) 0 0 0 0

Fz(KN) 5774 7464.52 8187 15469

M(KN-m) 0 0 0 0




4.10.1.1 Discussion:

The above analysis results compare the effects of dead load on the bridge in terms ofthe

bending moments and shears along the deck. The table compares these effects for both when

the stay cables are prestressed and when prestress force in stay cables is not considered. Note

here that the prestress force is not directly applied in SAP 2000. But it is induced in terms of

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

Fz(KN)

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50 | P a g e

strain load in the stay cables corresponding to the stress applied. When we compare the

support reactions we conclude that,

i. When the cables are not prestressed the reaction at the end supports are greater that when

the cables are prestressed.

ii. The reaction at central Pier base is higher when the stay cables are prestressed than

unstressed stay cables. This behavior is justified because stay cables carry the load of the deck

to the pylon which in turn goes to P3 when the stay-cables are stressed and in unstressed stay-

cables state the load bearded by stay cables now goes to the P2 abutment and P4 Pier.

51 | P a g e

4.10.2 Dead and Live Load Analysis Results

ITEM Design

consultant

Vetting

consultant

Analysis by

us With

prestressed

stay cables

Analysis by us W/O


Max positive Moment

(KN-m)

61409 157368 147492 308679.2

Max negative Moment

(KN-m)

776591 829243 608522 1152 226

Max Shear (KN) 31148 35911 30873.49 40 195.2


Fz(KN) 5776 8440 7908.937 14987.394


Fz(KN) 175827 169317 180109.95 165749.26

M(KN-m) 36857 17463 38856.258 18114


Fz(KN) 5774 8726 8802.568 16084.804

Table 4.7- Analysis Results in Tabular form

As discussed earlier in Section 4.8 “Dead load and Live load combination”, those result are

displayed in tabular form. Moment distribution and shear variation are explained earlier

Graphical display of reaction along vertical direction at Pier 2, Pier 3and Pier 4

52 | P a g e

Figure 4.12- Fz reaction in Support P2, P3 and P4

4.10.2.1 Discussion:

The live load considered is HS n 20-44 and the moment due to the live load is plotted The plot

shows us max positive and max negative moment at each section along the deck.

We note that the envelope shows the mid span bears higher positive moments whereas at P3

(Central pier) the native moments dominate.

The moments along the deck due to the deck are relatively smaller due to the live load as

compared with the dead load moments along the deck.

The internal prestressing force is applied at both end of the tendon profile which induces

positive moments at P3 and negative moments at the mid spans.

The load combination DEAD load + Live load + Prestress load gives us the net moments

experienced by the deck.

The reactions at the supports are also shown which show the same shift in reaction from side

supports (i.e. P2 and P4) to the central pier P3 when the stay cables are pre stressed.

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

200000

P2SUPPORT

P3SUPPORT

P4SUPPORT

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4.12 Stage Construction Analysis:

4.12.1 Creep Stresses in Concrete

Influence of the creep and drying shrinkage is crucial for step-by-step construction method of

erection.

The structural system of PC Extradosed Bridge changes during construction. As whole structure

is not erected at once, hence there is a change in the structural system during and after

erection. The statically indeterminate force occurs with the progress of creep due to the

restrained concrete, which in itself occurs due to change in the structural system. Due to

balance cantilever method of construction, the structural system during & after erection is

different.

4.13 Seismic Analysis for Expansion Joint Displacement :

Seismic Analysis is a subset of structural analysis and is the calculation of the response of a

building structure to earthquakes. It is part of the process of structural design, earthquake

engineering or structural assessment and retrofit in regions where earthquakes are prevalent.

As seen in the figure, a building has the potential to ‘wave’ back and forth during an earthquake

(or even a severe wind storm). This is called the ‘fundamental mode’, and is the

lowest frequency of building response. Most buildings, however, have higher modes of

response, which are uniquely activated during earthquakes. The figure just shows the second

mode, but there are higher ‘shimmy’ (abnormal vibration) modes. Nevertheless, the first and

second modes tend to cause the most damage in most cases.

4.13.1 Linear Dynamic Analysis:

Static procedures are appropriate when higher mode effects are not significant. This is

generally true for short, regular buildings. Therefore, for tall buildings, buildings with torsional

irregularities, or non-orthogonal systems, a dynamic procedure is required. In the linear

dynamic procedure, the building is modelled as a multi-degree-of-freedom (MDOF) system with

a linear elastic stiffness matrix and an equivalent viscous damping matrix.

The seismic input is modeled using either modal spectral analysis or time history analysis but in

both cases, the corresponding internal forces and displacements are determined using linear

elastic analysis. The advantage of these linear dynamic procedures with respect to linear static

54 | P a g e

procedures is that higher modes can be considered. However, they are based on linear elastic

response and hence the applicability decreases with increasing nonlinear behavior, which is

approximated by global force reduction factors.

In linear dynamic analysis, the response of the structure to ground motion is calculated in

the time domain, and all phase information is therefore maintained. Only linear properties are

assumed. The analytical method can use modal decomposition as a means of reducing the

degrees of freedom in the analysis.

4.13.2 Time History Analysis

Time-history analysis provides for linear or nonlinear evaluation of dynamic structural response

under loading which may vary according to the specified time function.

Six Degrees of Freedom are:

U1- Translation Parallel to Abutment R1- Rotation about Abutment

U2- Translation Normal to Abutment R2- Rotation about Line Normal to Abutment

U3- Translation Vertical R3- Rotation about Vertical

Time history analysis is done in all three directions i.e. U1, U2 and U3.

4.13.4 Result of Time History Analysis:

Time History ( U1 )

(Acceleration along the Deck)

Accelaration (m/sec2) Displacement (cm)

Girder at P2 support 0.542 32

Top of P3 column 3.131 26


Table 4.9- Time History in longitudinal direction

Time History ( U2 )

(Acceleration across the Deck)

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Acceleration (m/sec2) Displacement (cm)


Top of P3 column 2.899 30


Table 4.10-time history in transverse direction

Time History ( U3 )

(Acceleration perpendicular the Deck)

Accelaration (m/sec2) Displacement (cm)

Girder at P2 support 0.004 0.0

Top of P3 column 0.045 0.1

Girder at P4 support 0.009 0.0

Table 4.11-Time history perpendicular the deck

The allowable joint movement is 350`mm in longitudinal direction and almost data are within

the range in analytical results

Higher safety margin is available. The probable reason is difference in the modeling of support

and design engineers’ decision on safety margin as Muzaffarabad has experienced most

devastating earthquake in Pakistan. Though expansion joint at approach bridges may not have

same displacement range but it is a fact that increase in the size of expansion joint

tremendously increases its cost.

Hence localized minor damage (of concrete cover) may be acceptable rather increasing bridge

cost to acceptable values.

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Appendix A

HS20-44 Loading

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Appendix B

Summary of Extradosed Bridges

Name and Opera- -Deck Depth x Width Picture Location tional -Span Lengths

Date -Deck Description

1 Ganter Bridge, 1980

Switzerland

2 Arrêt-Darré Proposed Viaduct, France

3 Barton Creek 1987

Bridge, Austin,

USA

4 Socorridos 1993

Bridge, Madeira,

Portugal

5 Odawara Blueway 1994 Bridge, Japan

6 Saint-Rémy-de- 1996

Maurienne Bridge,

Savoie, France

7 Tsukuhara Bridge, 1997 Japan

2.5 - 5 x 10 127.0 + 174.0 + 127.0 Wide single cell concrete box girder,

cable-panel stayed.

3.75 x 20.5 60.0 + 100.0 + 100.0 + 100.0 + 100.0 + 52.0

Single cell concrete box girder with voided webs and

struts supporting deck cantilevers.

3.7 - 10.7 x 17.7 47.6 + 103.6 + 57.9 Single cell concrete box girder with webs

inclined inwards into a central fin above the

deck level, and transverse struts supporting

the deck slab. 3.5 x 20 54.0 + 85.0 + 106.0 + 86.0 Single cell concrete box girder, cable-

panel stayed.

2.2 - 3.5 x 13 73.3 + 122.3 + 73.3 Wide double cell concrete box girder. 2.2 x 13.4 52.4 + 48.5 U shaped concrete deck with transverse

ribs between edge beams.

3 - 5.5 x 12.8 65.4 + 180.0 + 76.4 Wide single cell concrete box girder.

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Summary of Extradosed Bridges (continued) Name and Opera- -Deck Depth x Width Picture

Location tional -Span Lengths


8 Kanisawa Bridge, 1998 3.3 - 5.6 x 17.5

Japan 99.3 + 180.0 + 99.3

Concrete box girder.

9 Shin-Karato 1998 2.5 - 3.5 x 11.5

Bridge, Kobe, 74.1 + 140.0 + 69.1

Japan Two and three cell concrete box girder.

10 Sunniberg Bridge, 1998 1.1 x 12.375

Switzerland 59.0 + 128.0 + 140.0 + 134.0 + 65.0

Concrete slab with edge stiffening beams.

11 Santanigawa

(Mitanigawa)

Bridge, Japan

12 Second Mandaue -

Mactan (Marcelo

Fernan) Bridge,

Mactan, Philippines

13 Matakina Bridge,

Nago, Japan

1999 2.5 - 6.5 x 20.4 57.9 + 92.9 Double cell concrete box girder.

1999 3.3 - 5.1 x 18 111.5 + 185.0 + 111.5 Three cell concrete box girder. Photo from www.jsce.or.jp/committee/tanaka-sho/jyushou Kasuga 2006

2000 3.5 - 6 x 11.3 109.3 + 89.3 Single cell concrete box girder.

14 Pakse (Lao-

2000 3 - 6.5 x 13.8

Nippon) Bridge, 52.0 + 123.0 + 143.0 + 91.5 + 34.5

Laos Single cell concrete box girder.

15 Sajiki Bridge, Japan 2000 2.1 - 3.2 x 11

60.8 + 105.0 + 57.5

Summary of

Extradosed Bridges (continued)

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Name and Opera- -Deck Depth x Width Picture Location tional -Span Lengths


16 Shikari Bridge,

Japan

17 Surikamigawa

Bridge, Japan

18 Wuhu Yangtze

River Bridge,

Wuhan, China

19 Yukisawa-Ohashi Bridge, Japan

2000 3 - 6 x 23 94.0 + 140.0 + 140.0 + 140.0 + 94.0

Concrete box girder.

Photo from www.jsce.or.jp/committee/tanaka-sho/jyushou Stroh et al. 2003

2000 2.8 - 5 x 9.2

84.82 2000 15 x 23.4 180.0 + 312.0 + 180.0 Double-decker steel truss with composite deck slab

on top roadway, two rail lines on bottom level. 2000 2 - 3.5 x 15.8 70.3 + 71.0 + 34.4

Two cell concrete box girder with wide

sidewalks on deck cantilever overhangs

outside of cable planes. 20 Hozu Bridge, Japan

21 Ibi River

Bridge, Japan

2001 2.8 x 15.3 33.0 + 50.0 + 76.0 + 100.0 + 76.0 + 31.0 Single

cell concrete box girder.

2001 4.3 - 7.3 x 33 154 + 271.5 + 271.5 + 271.5 + 271.5 + 157 Hybrid cross

section: four cell concrete box girder near piers and steel box

girder in central 100 m with moment and shear connection.

22 Kiso River Bridge, 2001 4.3 - 7.3 x 33

Japan 160.0 + 275.0 + 275.0 + 275.0 + 160.0

Hybrid cross section: four cell concrete box

girder near piers and steel box girder in central

100 m with moment and shear connection.

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Summary of Extradosed Bridges (continued) Name and Opera- -Deck Depth x Width Picture Location tional -Span Lengths

Date -Deck Description 23 Miyakodagawa

Bridge, Japan

24 Nakanoike

Bridge, Japan

25 Fukaura

Bridge, Japan

26 Korror Babeldoap

Bridge, Palau

27 Sashikubo

Bridge, Japan

28 Shinkawa (Tobiuo)

Bridge, Hamamatsu,

Japan

29 Deba River

Bridge, Gipuzkoa,

Spain

30 Himi Bridge, Japan

2001 4 - 6.5 x 19.9 134.0 + 134.0 Parallel double cell box concrete box girders. 2001 2.5 - 4 x 21.4 60.6 + 60.6 2002 2.5 - 3 x 13.7 62.1 + 90.0 + 66 + 45.0 + 29.1 2002 3.5 - 7 x 11.6 82.0 + 247.0 + 82.0 Hybrid cross section: wide single concrete box

girder near piers and steel box girder in central 82

m. 2002 3.2 - 6.5 x 11.3 114.0 + 114.0 Concrete box

girder.

2002 2.4 - 4 x 25.8 38.5 + 45.0 + 90.0 + 130.0 + 80.5 Three cell

concrete box girder.

2003 2.7 x 13.9 42.0 - 66.0 - 42.0 U shaped concrete deck with transverse ribs

between edge beams.

2004 4 x 12.45 91.8 + 180.0 + 91.8 Single cell doubly composite box girder with

corrugated steel webs.

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31 Korong Bridge, 2004 2.5 x 15.85

Budapest, Hungary 52.26 + 61.98

Three cell concrete box girder stiffened with

transverse ribs.

32 Shin-Meisei

2004 3.5 x 19

Bridge, Japan 89.6 + 122.3 + 82.4

Three cell concrete trapezoidal box girder.

33 Tatekoshi Bridge, 2004 1.8 - 2.9 x 19.14

Japan 56.3 + 55.3

34 Sannohe-Boukyo 2005 3.5 - 6.5 x 13.45

Bridge, Aomori, 99.9 + 200.0 + 99.9

Japan Concrete box girder.

35 Domovinski

2006 3.55 x 34

Bridge over the 48 + 6x60 + 72 + 120 + 72 + 2x60 + 48

River Sava, Croatia Five cell concrete box girder supports light rail

between cable planes.

36 Kack-Hwa First

2006 - x 31.1

Bridge, Gwangju, 55.0 + 115.0 + 100.0

South Korea Multiple cell concrete box girder.

37 Nanchiku Bridge, 2006 2.6 - 3.5 x 20.55

Japan 68.1 + 110.0 + 68.1

38 Rittoh Bridge, 2006 4.5 - 7.5 x 19.6

Japan 140 + 170 + 115 + 70 (Tokyo bound)

Three cell doubly composite box girder with

corrugated steel webs.

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39 Tagami Bridge, 2006 3 - 4.5 x 17.8

Japan 80.2 + 80.2

40 Third Bridge over 2006 2 - 2.5 x 17.4

Rio Branco, Brasil 54 + 90 + 54

Deck slab with L shaped edge beams (appears

as single box girder with incomplete bottom

slab) that taper to I beams at midspan.

41 Tokuyama Bridge, 2006 4 - 6.5 x 17.4

Japan 139.7 + 220.0 + 139.7

42 Yanagawa Bridge, 2006 4 - 6.5 x 17.4

Japan 130.7 + 130.7

43 Brazil-Peru 2007 2.35 - 3.35 x 16.8

Integration 65.0 - 110.0 -65.0

Bridge, Brazil Wide single cell concrete box girder.

44 Gum-Ga Grand 2007 - x 23

Bridge, 85.4 + 125.0 + 125.0 + 125.0 + 125.0 + 125.0 +

Chungcheongnam- Mulitple cell concrete box girder.

do, South Korea

45 Pyung-Yeo 2 2007 3.5 - 4 x 23.5

Bridge, Yeosu, 65.0 + 120.0 + 65.0

South Korea Four cell concrete box girder.

46 Second

2007 3.5 x 28.6

Vivekananda 55.0 + 7 x 110.0 + 55.0

Bridge over the Wide single cell trapezoidal box girder with

internal struts (Bang Na cross section).

Hooghly River,

Summary of Extradosed Bridges (continued)

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Name and Opera- -Deck Depth x Width Picture



47 Cho-Rack Bridge, 2008 - x 14

Dangjin, South 70.0 + 130.0 + 130.0 + 130.0 + 70.0

Korea Multiple cell concrete box girder.

48 North Arm 2008 3.4 x 10.31

Bridge (Canada 139.0 + 180.0 + 139.0

Line Extradosed Single cell concrete box girder for LRT.

Transit Bridge),

49 Trois Bassins

2008 4 - 7 x 22

Viaduct, Reunion, 18.6 - 126.0 - 104.4 - 75.6 - 43.2

France Single cell concrete box girder with steel struts

supporting long deck cantilevers.

50 Golden Ears

2009 2.7 - 4.5 x 31.5

Bridge, Canada 121.0 + 242.0 + 242.0 + 242.0 + 121.0

Steel box girders at edge of deck with

transverse floor beams composite with precast

concrete deck.

51 Pearl Harbor

2012 3.5 - 5 x 33.7

Memorial 75.9 + 157.0 + 75.9

(Quinnipiac) Parallel five cell concrete box girders with

inclined exterior webs.

Bridge, New

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REFRENCES:

i Survey of Pakistan ii Google Earth iii http://www.infovisual.info/05/029_en.html 4http://www.ikonet.com/en/visualdictionary/transport-and-machinery/road-transport/fixed-bridges/arch-bridge.php 5 http://writepass.co.uk/journal/wpcontent/uploads/2012/12/1231. 6 http://kids.britannica.com/comptons/art-18377/A-suspension-bridge-with-forces-of-tension-represented-by-red vii Akio Kasuga, Development of extradosed structures in the bridge construction & Recent technology of prestressed concrete bridges in Japan

viii Menn, Christan. (1990). Prestressed Concrete Bridges.

Birkhauser Verlag, Basel, Switzerland.

ix Mermigas , konstatinos kris (2008), Behaviour and Design of EXTRADOSED BRIDGES x Mermigas , konstatinos kris (2008), Behaviour and Design of EXTRADOSED BRIDGES xi Mermigas , konstatinos kris (2008), Behaviour and Design of EXTRADOSED BRIDGES, Page 46,Chap 3, VOl 1 xii Mermigas , konstatinos kris (2008), Behaviour and Design of EXTRADOSED BRIDGES, Mermigas Section 3 ,

xiii Mermigas , konstatinos kris (2008), Behaviour and Design of EXTRADOSED BRIDGES, Mermigas Section 3.4.9 ,

http://www.infovisual.info/05/029_en.html

http://kids.britannica.com/comptons/art-18377/A-suspension-bridge-with-forces-of-tension-represented-by-red

http://kids.britannica.com/comptons/art-18377/A-suspension-bridge-with-forces-of-tension-represented-by-red

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xiv Chio Gustave Chiao, Structural behavior and design criteria of extradosed bridges: general insight and state of the art, Page 391 xv Jacques Mathivat, The Cantilever Construction Of Prestressed Concrete Bridges Page 383 , Structural behavior and design criteria of extradosed bridges: general insight and state of the art xvi Mermigas , konstatinos kris (2008), Behaviour and Design of EXTRADOSED BRIDGES , Page 54 VOL 1, , xvii Gustavo Chio, Structural behavior and design criteria of extradosed bridges: general insight and state of the art xviii Dos Santos, Structural behavior and design criteria of extradosed bridges: general insight and state of the art xix Mermigas , konstatinos kris (2008),, Behaviour and Design of EXTRADOSED BRIDGES, Page 59, 54 VOL 1, xx Akio Kasuga, Development of extradosed structures in the bridge construction & Recent technology of prestressed concrete bridges in Japan xxi Construction Engineering Report on Naluchi Bridge (Cable Stayed Bridge) by Ghulam Rasool & Co. xxii Pictures taken at Muzaffarabad xxiii Construction Engineering Report on Naluchi Bridge (Cable Stayed Bridge) by Ghulam Rasool & Co. xxiv Nespak, (2008) ,Initail Draft report Nalchi Muzzafrabad xxv (LRFD C4.5.1, AASHTO 2007).

http://www.goodreads.com/book/show/4568854-the-cantilever-construction-of-prestressed-concrete-bridges

http://www.goodreads.com/book/show/4568854-the-cantilever-construction-of-prestressed-concrete-bridges

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xxvi Caltrans (2008). Bridge Design Specification , CA 4.5.2.2, xxvii AASHTO 4.6.1 ,AASHTO Guide Specification for LRFD Sesmic Bridge Design xxviii Construction Engineering Report on Naluchi Bridge (Cable Stayed Bridge) by Ghulam Rasool & Co xxix Nespak, (2008) ,Initail Draft report Nalchi Muzzafrabad

Structural Analysis of Extradozed Bridge in Naluchi,Muzaffrabad

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