Connexion du pont métallique translat

8/3/2019 Connexion du pont mtallique translat

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Institute de Technologie du Cambodge Rapport de Construction Mtallique

Professor: LY Hav Group 6 Page 1

ContentsI. Introduction ........................................................................................................................ 2II. Generality ........................................................................................................................... 2

1. Definition ........................................................................................................................ 22. I-beam girder and box girder............................................................................................ 3

III. Box-girder Bridge in Boisbriand, Quebec ........................................................................ 4Summary: ............................................................................................................................... 4Bridge Description: ..................... ......................................... ......................................... .......... 4

IV. Different assembly methods ............................................................................................. 6V. The general concept............................................................................................................ 6

a. Bolting ............................................................................................................................ 6b. Welding ........................................................................................................................... 6

VI. The method of assembly ................................................................................................... 7a. Bolting ............................................................................................................................ 7

b. Welding ........................................................................................................................... 7VII. Assemblies used in the project......................................................................................... 7VIII. Conclusion: ..................................................................................................................... 9Reference: ................................................................................................................................ 10


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Girder Bridge

I. IntroductionIn the name of student in the fourth year in Institute of Technology of Cambodia

(ITC), we have to do research about the steel structure in order to realize the concepts of

calculating and gainmore general knowledge about steel construction.The lesson in the

class is not provide us enough knowledge to understand this course deeply, so professor

lets students to do a research more about different topics. As a result, our group was doing

a research about the girder bridge.

First ofall, we have to know what the bridge is. A bridge is a structure built to span

physical obstacles such as abody of water,valley, or road, for the purpose of providing

passage over the obstacle. Designs ofbridges vary depending on the function of the bridge,

the nature of the terrain where the bridge is constructed,and the material.There are six

main types ofbridges: girder bridges, cantilever bridges,arch bridges, suspensionbridges,cable-stayed bridges and truss bridges. For this research, we focus deeply on girder

bridges only.

II. Generality1. Definition

Beambridges are horizontal beams supported at each end by abutments, hence their

structural name of simply supported. When there is more than one span the intermediate

supports are known as piers. Weight on top of the beam pushes straight down on the

abutments at either end of the bridge.

Figure 1

There are four types ofbeams: the beams souls full, the box girders,beams, trusses and

beams bow-strings. The constructional material of beams can be metal, reinforced

concrete, prestressed concrete, wood or,more recently, composite materials.


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Figure 2

2. I-beam girder and box girder

A girder bridge is perhaps the most commonand mostbasic bridge. Inmodern steel

girder bridges, the two most common girders are I-beam girders and box-girders.

The vertical plate in the middle is knownas the web,and the top and

bottom plates are referred to as flanges(figure 1).

A box girder is much the same as anI-beam girder except

that, obviously, it takes the shape ofabox.The typical

box girder has two webs and two flanges (figure 2).

Now that we know the basic physical differences between box girders and I-beam

girders, let's lookat the advantages and disadvantages of each. AnI-beamisvery simple to

designand build and works very well inmost cases. However, if the bridge contains any

curves, the beams become subject to twisting forces, also known as torque. The added

second web inabox girder adds stability and increases resistance to twisting forces.This

makes the box girder the ideal choice for bridges with any significant curve in them.

Box girders,being more stable are also able to span greater distances and are often

used for longer spans, where I-beams would notbe sufficiently strong or stable.

However, the design and fabrication of box girders is more difficult than that of I-

beams. For example, in order to weld the inside seams ofabox girder,a human or welding

robotmustbe able to operate inside the box girder.

Figure 3


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III. Box-girder Bridge in Boisbriand, Quebec

Summary:Comprehensive redevelopment of the interchange of highways 15 and 640 in Boisbriand

requires the construction of several curve bridges. This article describes the process of bridgedesign of the ramp above the 15 and 640 freeways. The geometry of the ramp to cross the

highways and the criteria of aesthetics were the decisive factors in choosing ranges, bridge

construction in curves, a continuous structure of three spans of 49, 52 and 36 m curve with a

mean radius of 120 m and another right continuous structure of two spans of 45 m. Given the

high torsional stiffness required and length of spans, an apron made of two steel box girders

proved to be the best choice for this complex structure.

The complexity of the stress distribution in the box girders and their specific geometry

impose additional requirements on the details of assembly of the components of the structural

steel. Some of the details used in this project are reported and discussed.

The box girder bridges have become increasingly popular due to their good behavior

compared to girder bridges assembled in I. They are cheaper, more stable, and structurally more

efficient and have a more aesthetic.


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Bridge Description:

The design of the curved section that is the subject of this article has an average radius of

curvature of 120m over a length of 137 m. Given the span lengths and the limit of 5 m minimum

clearance required under the structure, the selected section of the deck is made of two steel box

girders spaced 4.6 m center-center. The composite action of the concrete slab with steel sectionis provided through the shear connectors. The two chambers are supported by bearings fixed to

the battery 2, 3 and 5-way supports the abutments and the battery 4.

The thickness of the top flanges ranges from 30 mm to 50 mm in span over batteries

while the thickness of the bottom flange varies from 20 mm to 50 mm in span over batteries.

Souls have a height and a constant thickness of 1700 mm and 14 mm respectively.


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Connection of Girder BridgeIV. Different assembly methods

Assemblies currently used in steel construction can be classified into two broad

headings:

y those that allow the transmission of forces by mechanical contact, we gather under thename of mechanical assemblies;

y those who provide continuity of the metal and the joints which consist of variouswelding processes (always autogenously).

V. The general concepta. Bolting

In this type of assembly, the bolt works in tension and can withstand high loads because

it is made of steel with high yield. The pressure exerted by the bolt is distributed over the

contact surface with steel washers grade very similar, so that the forces exerted on the

sheets pass through the rings and the presence of holes weakens structure.Avec not the high-

strength bolt, force transmission is achieved by adhesion (attachment) despises in touch.

Under the clamping force and thanks to the abrasion resistance of wetted parts, assembled

The items cannot slide.

The ordinary bolt (or bolt raw or black bolt) is placed in holes that its diameter is larger

than 1 to 2 mm of diameter nominal of bolt, providing a game setting, this game can be

decrease in the cases where it is desired reduce the relative displacements despises .Les high-

strength bolts are class 8.8, 10.9, 12.9 and 14.9 (Rn from 800 to 1400 MPa, Re from 640 to

1260 MPa).

b. Welding

Welding is a metallurgical micro-operation is to run a cord linking the melted edges of

two pieces and is called homogeneous when these two parts, and the solder joint, have a

chemical composition identical or similar, and heterogeneous in other cases.

It ensures continuity of the metal piece, giving it the characteristics of the assembly level

equivalent to that of the metal assembly (mechanical, thermal, chemical, electrical, sealing,

durability ...). It meets the high demands. In addition, it is durable (insensitive to temperature

variations, weather ...). And it ensures the tightness of the welded part.Welding residues are called "projections" or "gratons" (small pins that stick to the metal).

Welding has three major families of problems:

y Operative (Development of welding procedure)y Global (the solder is, it breaks elsewhere), andy Metallurgical (case of steel welding 9% Ni in uniform).


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VI. The method of assembly

There are four necessities for assembly modeling: joint beam, beam-column connection,

angle frame, and the column bottom. As elsewhere, there are two types of assembly:

a.B

oltingFor bolted connections, in general, it must be for the structural safety, serviceability,

fatigue, and quality assurance.

Structural safety of the bolt can be verified according to the basic principle expressed by:

M

k

dd

RRE

K!e

dE

: Design value of the effects of actions

dR

: Design value of resistance

MK : Resistance factor

b. Welding

For welding connections, in general, it must be for the structural safety, serviceability,

fatigue, and quality assurance.

Structural safety of the bolt can be verified according to the basic principle expressed by:

M

k

dd

RRE

K!e

dE : Design value of the effects of actions

dR : Design value of resistance

MK : Resistance factor; 25.1

2!

MK

VII. Assemblies used in the project

Specific details

The complexity of the forces acting on the box girders and their particular geometry impose

additional requirements on the details of assembly of the components of the structural steel. The

most important recommendations include, among other things:

details used should facilitate future inspection of the boxes;

details of assemblies of the diaphragms at the supports must be adjusted to take accountof the great torsional rigidity of the box and installation methods;

all details must be designed to minimize fatigue stress; a layer of light colored paint to be applied inside the enclosure to facilitate future

inspection and crack detection.


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Because of the shape of the box almost closed, the stiffeners to intermediate bracing must be

attached to the soles to reduce local stresses due to distortion of the section. To enable

continuous welding of the soul with the bottom plate, the stiffeners are stopped at a distance of

90 mm above the bottom flange. After assembly of the box, a Welded gusset is added to ensure

continuity between the stiffener and the bottom plate (Figure 9).

Drainage holes (Figure 10) is another important detail of the steel box. The holes are

located in the bottom soles at about 100 mm of the soul. The drains can not only remove the

accumulated water inside but also improve ventilation inside the box. To prevent animals from

entering through the drainage holes, a grid of stainless steel protection covers the opening.

External support to the diaphragms, designed as deep beams, subjected to bending due to

shear and torsion in the box girders. Large bending moments acting on the diaphragms have

required the development of the rigid in flexion (Figure 11a). Particular attention was paid to the

details of fatigue in order to ensure a direct and natural transmission of effort.


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For ease of installation and allow the replacement of slippery surfaces, the bumpers are

designed to be replaceable. In addition, to reduce the impact force and uniform pressure on the

contact surfaces, a neoprene pad installed on the fixed portion between the plate bumper and

sliding plate (Figure 14).

VIII. Conclusion:

The design of the bridge box girder steel curved horizontally posed significant

challenges. The realization of this project allowed Dessau to accumulate knowledge and

experience on the design of such structures. We like to thank Mr. LY Hav, Prof. of Steel

Construction, for the opportunity they provided us knowledge convenience the field of metal

construction, particularly steel beam bridge.


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Reference:Manfred A. Hirt, Rolf Bez et Alain Nussbaumer, 2006,lEcole polytechnique fdration de Lausanne,

Construction Mtallique , Volume 10

http://www.otua.org/v3/documentation/soudage/assemblage.htm

http://fr.wikipedia.org/wiki/Pont_m%C3%A9tallique

http://fr.wikipedia.org/wiki/Boulon

http://fr.wikipedia.org/wiki/Soudage

Connexion du pont métallique translat

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