Ch1 Introduction (Steel Bridges تصميم الكباري المعدنية & Prof. Dr. Metwally Abu-Hamd)

STEEL BRIDGES
METWALLY ABU-HAMD
Head of Structural Engineering Dept
Professor of Bridge and Steel Structures
Faculty of Engineering, Cairo University

Any part of this book may be reproduced by any means
WITHOUT the written permission of the author.

Preface
___________________________________________
Bridges have always fascinated people, be it a primitive bridge over a
canal or one of the magnificent long span modern bridges. People built
bridges to challenge nature where some obstacles like rivers, valleys, or
traffic block the way they want to pass through. Our transportation system
would not exist without bridges. Their existence allows million of people,
cars, and trains to travel every day and everywhere they want to go. It is
obvious that both our economy and our society could not function without the
technology of bridge engineering.
Bridge building is one of the difficult constructional endeavors that both
attracts and challenges structural engineers. The design of such complex
structures requires a great deal of knowledge and experience. Depending on
the bridge span to be covered, several types of bridge systems exist.
Examples of bridge systems are beam bridges for short and moderate spans,
arch bridges for moderate spans, and cable stayed bridges and suspension
bridges for long spans.
This book covers the design of steel bridges in general with emphasis on
bridge systems commonly used to cover short and moderate spans, namely
plate girder bridges, box girder bridges, and truss bridges. The book is
intended for senior year college students and practicing bridge engineers.
The contents of the book are organized into two parts: the first four
chapters cover the design of steel bridges in general while the other four
chapters cover the design of specific bridge types. Chapter 1 describes the
different structural systems of steel bridges. Chapter 2 presents the design
loads on roadway and railway bridges. Chapter 3 presents the design
considerations. Chapter 4 covers the design of roadway and railway bridge
floor. Chapter 5 covers the design of plate girder bridges. Chapter 6 covers
the design of composite plate girders. Chapter 7 covers the design of box
girder bridges. Chapter 8 covers the design of truss bridges.
The author hopes that this book will enable structural engineers to design
and construct steel bridges with better safety and economy.
Dr Metwally Abu-Hamd
Professor of Steel and Bridge Structures
Faculty of Engineering
Cairo University
Giza, 2007

CONTENTS
___________________________________________
1: INTRODUCTION
1.1 GENERAL 2
1.2 TYPES OF BRIDGES 5
1.3 MATERIALS FOR BRIDGE CONSTRUCTION 20
2: DESIGN LOADS ON BRIDGES
2.1 INTRODUCTION 26
2.2 ROADWAY DESIGN LOADINGS 26
2.3 RAILWAY DESIGN LOADINGS 32
2.4 OTHER LOADS ON BRIDGES 36
3: DESIGN CONSIDERATIONS
3.1 DESIGN PHILOSOPHIES 42
3.2 ALLOWABLE STRESSES FOR STRUCTURAL STEEL 43
3.3 FATIGUE 65
3.4 ALLOWABLE STRESSES FOR WELDED JOINTS 106
3.5 ALLOWABLE STRESSES FOR BOLTED JOINTS 107
4: BRIDGE FLOORS
4.1 INTRODUCTION 116
4.2 STRUCTURAL SYSTEMS OF BRIDGE FLOORS 117
4.3 DESIGN CONSIDERATIONS 122
4.4 DESIGN EXAMPLES 125

5: PLATE GIRDER BRIDGES
5.2 GENERAL DESIGN CONSIDERATIONS 148
5.3 INFLUENCE OF BUCKLING ON GIRDERS DESIGN 154
5.4 ACTUAL STRENGTH OF PLATE GIRDER ELEMENTS 173
5.5 FLANGE PLATE CURTAILMENT 181
5.6 DESIGN DETAILS 183
5.7 FLANGE-TO-WEB CONNECTION 183
5.8 STIFFENERS 187
5.9 SPLICES 194
5.9.4 DESIGN 200
5.10 BRIDGE BRACINGS 203
5.11 BRIDGE BEARINGS 208
5.12 DESIGN EXAMPLE 218
6: COMPOSITE PLATE GIRDER BRIDGES
6.1 GENERAL 240
6.2 COMPONENTS OF COMPOSITE GIRDERS 243
6.3 DESIGN CONSIDERATIONS 245
6.4 SHEAR CONNECTORS 257
7: BOX GIRDER BRIDGES
7.2 CROSS SECTION ARRANGEMENTS 278
7.3 BEHAVIOR OF BOX GIRDER BRIDGES 282
7.4 EFFECT BENDING 284
7.5 EFFECT OF TORSION 291
7.6 DESIGN EXAMPLE 306
8: TRUSS BRIDGES
8.1 TRUSS TYPES & CHARACTERISTICS 312
8.2 DESIGN OF TRUSS MEMBERS 318
8.3 GENERAL DESIGN PRINCIPLES 320
8.4 DESIGN OF TRUSS MEMBERS 322
8.5 DESIGN OF TRUSS CONNECTIONS 329

Chapter 1: Introduction
CHAPTER 1
INTRODUCTION

Steel Bridges
CHAPTER 1
INTRODUCTION
1.1 GENERAL
1.1.1 Historical Background
People have always needed to transport themselves and their goods from
one place to another. In early times, waterways were used wherever possible.
Navigable waterways, however, do not always go in the direction desired or
may not be always available. Therefore, it has been necessary to develop land
transportation methods and means of crossing waterways and valleys.
Roadway and railway development have therefore become an absolute
necessity for economic development. The rapid economic development in
Europe, USA, and Japan could not take place until land transportation was
developed. Even today, one important factor that has caused many countries
to lag behind in economic development is the lack of good land
transportation systems.
An important element of land transportation systems is the bridge. A
bridge is a structure that carries a service (which may be highway or railway
traffic, a footpath, public utilities, etc.) over an obstacle (which may be
another road or railway, a river, a valley, etc.), and then transfers the loads
from the service to the foundations at ground level.
The history of bridge engineering, which began with stone and wooden
structures in the first century BC, can be said to be the history of the
evolution of civil engineering. It is not possible to date humanity’s
conception and creation of the first bridge. Perhaps people derived the first
concept in bridge building from nature. The idea of a bridge might have
developed from a tree trunk that had fallen across a canal. Early bridges
consisted of simple short spans of stone slabs or tree trunks. For longer spans,

Chapter 1: Introduction 3
strands of bamboo or vine were hung between two trees across a stream to
make a suspension bridge.
The introduction of new materials – plain, reinforced, and pre-stressed
concrete; cast iron; wrought iron; and steel – evolved gradually within the
last two centuries. According to known records, the first use of iron in
bridges was a chain bridge built in 1734 in Prussia. Concrete was first used in
1840 for a 12-m span bridge in France. Reinforced concrete was not used in
bridge construction until the beginning of the twentieth century. Pre-stressed
concrete was introduced in 1927. These developments, coupled with
advances in structural engineering and construction technology, led to the
introduction of different forms of bridges having increasingly longer spans
and more load carrying capacities.
1.1.2 Bridge Components
In Figure 1.1 the principal components of a bridge structure are shown.
The two basic parts are:
(1) the UsubstructureU; which includes the piers, the abutments and the
foundations.
(2) the UsuperstructureU; which consists of:
a) the bridge deck, which supports the direct loads due to traffic and all
the other permanent loads to which the structure is subjected.
In roadway bridges it includes the deck slab, Fig. 1.1b.
In railway bridges it includes the rails and sleepers, Fig. 1.1c
b) the floor beams, which transmit loads from the bridge deck to the
bridge main girders. They consist of longitudinal beams, called
stringers, and transversal beams, called cross girders, Fig. 1.1c.
c) the main girders, which transmit the bridge vertical loads to the
supports.
d) the bracings, which transmit lateral loads to the supports and also
provide lateral stability to compression members in the bridge, Fig.
1.1b.
The connection between the substructure and the superstructure is usually
made through bearings. However, rigid connections between the piers (and
sometimes the abutments) may be adopted, such as in frame bridges, Figs.
1.4a and 1.4b.

Steel Bridges
a) Bridge Elevation
b) Cross Section of a Roadway Bridge
c) Cross Section of a Railway Bridge
Fig. 1.1 Principal Components of a Bridge Structure
stringer
bracing
main girder
Bridge deck

1.2 TYPES OF BRIDGES
Bridges can be classified in several ways depending on the objective of
classification. The necessity of classifying bridges in various ways has grown
as bridges have evolved from short simple beam bridges to very long
suspension bridges. Bridges may be classified in terms of the bridge’s
superstructure according to any of the following classifications:
1. Materials of Construction
2. Usage
3. Position
4. Structural Forms.
5. Span Lengths
A brief description of these bridge classifications is given next.
1.2.1 Bridge Classification by Materials of Construction
Bridges can be identified by the materials from which their main girders
are constructed. The most commonly used materials are steel and concrete.
This classification does not mean that only one kind of material is used
exclusively to build these bridges in their entirety. Often, a combination of
materials is used in bridge construction. For example, a bridge may have a
reinforced concrete deck and steel main girders.
1.2.2 Bridge Classification by Usage
Bridges can be classified according to the traffic they carry as roadway,
railway, Fig. 1.2, and footbridges, Fig. 1.3. In addition, there are bridges that
carry non-vehicular traffic and loads such as pipeline bridges and conveyor
bridges.

Steel Bridges
Fig. 1.2 Railway Through Bridge
Fig. 1.3 Foot Bridge

1.2.3 Bridge Classification by Position
Most bridges are fixed in place. However, to provide sufficient vertical
clearance to facilitate navigation through spanned waterways, bridges are
made movable; i.e., the bridge superstructure changes its position relative to
the roads that they link. In general, three kinds of movable bridges exist:
1. The bascule bridge, which has a rotational motion in the vertical
plane, Fig. 1.4a.
Fig. 1.4 a) Bascule Bridge
2. The lift bridge, which has a translational motion in the vertical plane,
Fig. 1.4b,
Fig. 1.4 b) Lift Bridge

Steel Bridges
3. The swing bridge, which has a rotational motion in the horizontal plane,
Fig. 1.4c.
Fig. 1.4 c) Swing Bridge
1.2.4 Bridge Classification by Structural Form
From an engineering perspective, bridges are best classified by their
structural forms because the methods of analysis used in bridge design
depend on the structural system of the bridge. Also, certain types of structural
forms are suitable for certain span ranges.
Structural form refers to the load resisting mechanism of a bridge by which
it transfers various loads from the bridge deck to the foundation. In different
types of bridges, loads follow different paths as they are first applied on the
deck and finally resolved in the earth below. From this perspective, several
structural systems are used in the elements of the bridge superstructure. It is
common in bridge terminology to distinguish between:
a. structural systems in the transversal direction, and
b. structural systems in the longitudinal direction.
The structural systems in the transversal direction are those used for the
bridge deck and floor structure to transfer loads to the bridge main girder.
Details of different systems used in both roadway and railway bridges are
given in Chapter 4.
The structural systems in the longitudinal direction are those used for the
bridge main girders to transfer loads to the supporting foundations. It should
be understood that bridge structures are basically three-dimensional systems

which are only split into these two basic systems for the sake of
understanding their behavior and simplifying structural analysis.
The longitudinal structural system of a bridge may be one of the following
types:
i) Bridges Carrying Loads Mainly by Bending: a) beam bridges
b) frame bridges
ii)Bridges Carrying Loads Mainly by Axial Forces: a) arch bridges
b) cable stayed bridges
c) suspension bridges.
The cross-section of the main girder incorporated in all these bridge types
may be a solid web girder or a truss girder depending on the values of the
design straining actions. Solid web girders dimensions are limited by the
requirements imposed by fabrication, transportation, and erection. Practical
maximum section depths of solid web girders range from 3 to 4 m for
economical design. If the required design exceeds this limit, a truss girder has
to be used, see Fig. 1.5.
Fig. 1.5 Truss Bridge
A truss used as a girder in flexure carries its bending moments by
developing axial loads in its chords, and its shears by developing axial loads
in its web members. Truss bridges are not specific bridge forms in themselves
– rather, trusses are used to perform the functions of specific members in one
of the types above. For example, a girder in flexure or an arch rib in axial
compression may be designed as a truss rather than as a solid web plate
girder.

Steel Bridges
1.2.4.1) Bridges Carrying Loads by Bending
By far the majority of bridges are of this type. The loads are transferred to
the bearings and piers and hence to the ground by beams acting in bending,
i.e. the bridges obtain their load-carrying resistance from the ability of the
beams to resist bending moments and shear forces. This type of bridge will
thus be referred to generally as a girder bridge.
Beam bridges are the most common and the simplest type of bridges.
These may use statically determinate beams (simply supported, Fig. 1.6a, or
cantilever beams, Fig. 1.6b) or continuous beams, Fig. 1.6c. Examples of
beam bridges are shown in Fig. 1.7:
Calculation Models
(a) Simply supported
(b) Cantilever Beam
(c) Continuous Beam
Structural System
Fig. 1.6 Bridge Systems Carrying Loads by Bending, Beam Bridges

(a) 14th Street Bridge over the Potomac River (USA). Continuous riveted
steel girders. Note the absence of internal hinges, and the roller supports
at the piers
(b) Continuous steel box girder bridge over the Rhine, Bonn, Germany,
1967. Note the varying depth of the box sections
Fig. 1.7 Examples of Beam Bridges

Steel Bridges
Simply supported beams are usually adopted only for very small spans (up
to 25m). Continuous beams are one of the most common types of bridge.
Spans for this system may vary from short (less than 20 m) to medium (20 -
50 m) or long spans (> 100 m). In medium and long spans, continuous beams
with variable depth section are very often adopted for reasons of structural
behavior, economy and aesthetics. These systems are suitable for bridge
spans up to 200 m for solid web girders and up to 300 m for truss girders.
Frame bridges are one of the possible alternatives to continuous beams.
Avoiding bearings and providing a good structural system to support
horizontal longitudinal loads, e.g. earthquakes, frames have been adopted in
modern bridge either with vertical piers or with inclined columns (Fig. 1.8).
Fig. 1.8 Bridge Systems Carrying Loads by Bending,
Rigid Frames with Vertical or Inclined Legs

1.2.4.2) Bridges carrying Loads by Axial Forces
This type can be further subdivided into those bridges in which the primary
axial forces are compressive, e.g.; arches, Fig. 1.9, and those in which these
forces are tensile, e.g.; suspension bridges, Fig. 1.11, and cable-stayed
bridges, Fig. 1.13.
Arches have played an important role in the history of bridges. Several
outstanding examples have been built ranging from masonry arches built by
the Romans to modern pre-stressed concrete or steel arches with spans
reaching the order of 500 m.. The arch may work from below the deck, Fig.
1.9a, from above the deck, Fig. 1.9b, or be intermediate to the deck level, Fig.
1.9c. The most convenient solution is basically dependent on the topography
of the bridge site. In rocky sites and good geotechnical conditions for the
footings, an arch bridge of the type represented in Fig. 1.9a is usually an
appropriate solution both from the structural and aesthetic point of view.
Arches work basically as a structure under compressive stress.. The shape is
chosen in order to minimize bending moments under permanent loads. The
resultant force of the normal stresses at each cross-section must remain
within the central core of the cross-section in order to avoid tensile stresses in
the arch.
(a) Deck Bridge
(b) Through Bridge (Bow String)
(c) Semi-DeckSemi Through
Fig. 1.9 Bridge Systems Carrying Loads by Axial Forces; Arch Systems

Steel Bridges
a) Solid Web Arch Bridge
b) Sydney Harbor Arch Bridge, completed 1932. Almost the longest arch
bridge in the world (longest is Bayonne Bridge, New York, completed a
few months earlier, 1.5 m longer). Two-hinge arch, span between
abutments is 503 m to allow unobstructed passage for ships in Sydney
Harbor. Contains 50,300 tons of steel (37,000 in the arch). The widest
(49 m) bridge in the world.
Fig. 1.10 Examples of Arch Bridges

The ideal "inverted arch" in its simplest form is a cable. Cables are
adopted as principal structural elements in suspension bridges where the
main cable supports permanent and imposed loads on the deck (Fig. 1.11).
Good support conditions are required to resist the anchorage forces of the
cable. This system is suitable for bridge spans between 300 and 2000 m.
Fig. 1.11a Bridge Systems Carrying Loads by Axial Forces;
Suspension Bridges
Fig. 1.11b Section of a suspension bridge cable, showing it is made up
of a bundle of small cables

Steel Bridges
a) Golden Gate Bridge, 1937. Main span of 1280 m, was the longest
single span at that time and for 29 years afterwards.
b) Akashi-Kaiyko Suspension Bridge, Japan. Links city of Kobe with
Awaji Island. World’s longest bridge (Main Span 1991 m)
Fig. 1.12 Examples of Suspension Bridges

A simpler form of cable bridges has been used - Cable stayed bridges
(Fig. 1.13). They have been used for a range of spans, generally between 100
m and 500 m, where the suspension bridge is not an economical solution.
Cable stayed bridges may be used with a deck made of concrete or in steel.
Fig. 1.13 Bridge Systems Carrying Loads by Axial Forces;
Cable-Stayed Bridges
Pont du Normandie (River Seine, Le Harve, France). 856 m main span,
longest cable stayed bridge in the world up to 1999. Longest now is
Tatara Bridge, Japan, 890 m
Fig. 1.14 Example of Cable-Stayed Bridges

Steel Bridges
1.2.5 Bridge Classification by Span Lengths
In bridge engineering, it is customary to identify bridges according to their
span lengths as short span, medium span, and long span. Presently there are
no established criteria to exactly define the range of spans for these different
classifications. A common practice is to classify bridges by span lengths as
follows:
Short-span bridges less than 50 m
Medium-span bridges 50 to 200 m
Long-span bridges Over 200 m
This classification of bridges is useful only in selecting the structural form
most suitable for the bridge span considered, as shown in the following table.
Each form of bridge is suited to a particular range of spans. The Table also
records the longest span for each type of construction.
1.2.6 Selection of Structural System
Flat girders, i.e. girders of constant depth, are used for all shorter span
bridges of both simple spans and continuous construction up to spans of
around 30 m. Rolled sections are feasible and usually offer greater economy.
Above this span fabricated sections will be required.
Haunched girders are frequently used for continuous structures where the
main span exceeds 50m. They are more attractive in appearance and the

greater efficiency of the varying depth of construction usually more than
offsets the extra fabrication costs. Both haunched and flat girders can be
either plate girders or box girders. Development in the semi-automatic
manufacture of plate girders has markedly improved their relative economy.
This form of construction is likely to be the preferred solution for spans up to
60 m or so, if depth of construction is not unduly limited. Above 60 m span,
and significantly below that figure if either depth of construction is limited or
there is plan curvature, the box girder is likely to give greater economy.
Cantilever trusses were used during the early evolution of steel bridges.
They are rarely adopted for modern construction.
Arches or rigid frames may be suitable for special locations. For example,
an arch is the logical solution for a medium span across a steep-sided valley.
A tied arch is a suitable solution for a single span where construction depth is
limited and the presence of curved highway geometry or some other
obstruction conflicts with the back stays of a cable stayed bridge. Frame
bridges are usually suitable for short or medium spans. In a three span form
with sloping legs, they can provide an economic solution by reducing the
main span; they also have an attractive appearance. The risk of shipping
collision must be considered if sloping legs are used over navigable rivers.
Cable stayed bridges, being self anchored, are less dependent on good
ground conditions. However, the deck must be designed for the significant
axial forces from the horizontal component of the cable force. The
construction process is quicker than for a suspension bridge because the
cables and the deck are erected at the same time. Suspension or cable stayed
bridges are the only forms capable of achieving the longest spans. They are
clearly less suitable for road or rail bridges of short or medium spans.
The following Figure shows the development of different bridge systems
with the span over the years.

Steel Bridges
1.3 MATERIALS FOR BRIDGE CONSTRUCTION
Steel and concrete are the two major materials used in bridge construction.
For bridge decks, concrete is predominant. However, for long span bridges,
there can be a saving in using steel orthotropic plate decks with an asphalt
wearing surface. Concrete is also the predominant material for curbs,
sidewalks, parapets, and substructure.
1.3.1 Structural Steels
Structural steel used in bridge construction can be categorized into three
main types: (1) Carbon steel, (2) High-strength low-alloy steel, and (3) heat-
treated alloy steel. Fig. 1.15 shows typical stress strain curves.
a) Carbon Steel
b) High Strength Steel
Fig. 1.15 Stress Strain Curves for Structural Steels

1. Carbon steel: This is the cheapest steel available for structural use. This
type of steel is characterized by the following chemical analysis contents:
Carbon : 0.15 - 0.29 %
Copper : 0.60 %
Manganese: 1.65 %
Examples of these steels are St. 37 which has a minimum yield stress of 24
kg/mmP
2
P.
2. High-strength low-alloy steel: Structural steels included in this category
have a minimum yield stress of 28 kg/mmP
2
P. The improvement in the
mechanical properties is achieved by adding small amounts of alloy
elements such as chromium, columbium, molybdenum, nickel, or
vanadium. The total of alloying elements does not exceed 5 % of the total
composition of steel, hence the term 'low-alloy'. Examples of these steels
are St. 44 and St. 52.
3. Heat-treated alloy steel: These steels are obtained by heat-treating the
low-alloy steels to obtain higher yield strength, 60 to 90 kg/mmP
2
P. The
process of heat treating involves quenching or rapid cooling with water or
oil from 900 P
o
PC to about 150 - 200 P
o
PC, then tempering by reheating to at
least 600 P
o
PC, and then controlled cooling. These steels do not exhibit a
well-defined yield point like the carbon and low-alloy steel.
Consequently, their yield strengths are determined by the 0.2 percent
offset method.
1.3.1.1 Physical Properties of Steel:
Mass Density ρ = 7.85 t/mP
3
Modulus of Elasticity E = 2100 t/cmP
2
Shear Modulus G = 810 t/cmP
2
Poisson's Ratio υ = 0.3
Coefficient of Thermal Expansion α = 1.2 x 10P
-5
/ P
o
PC

Steel Bridges
1.3.1.2 Mechanical Properties of Steel
Egyptian Standard Specification No.260/71
Grade of
Steel
Nominal Values of Yield Stress FR
yR
and Ultimate Strength FR
u
Thickness t
t  40 mm 40 mm < t  100 mm
FR
y
(t/cmP
2
P)
FR
u
(t/cmP
2
P)
FR
y
(t/cmP
2
P)
FR
u
(t/cmP
2
P)
St 37 2.40 3.70 2.15 3.4
St 44 2.80 4.40 2.55 4.1
St 52 3.60 5.20 3.35 4.9
1.3.2 Welding Materials
Welding has become the predominant method for connecting parts of steel
bridges, especially with respect to shop fabrication. The development of
automatic welding has been a major factor in the fabrication of welded
bridges.
Structural steels may be welded by one of the following welding processes:
- Shielded Metal Arc Welding (S.M.A.W.): used for manual welding.
- Submerged Arc Welding (S.A.W.): used for automatic welding.
- Gas Metal Arc Welding (G.M.A.W.): used for semi-automatic welding.
The appropriate electrode types used in the weld process as well as their
yield and tensile strengths are given in Table 1 according to ECP 2001.

Table (1) Electrodes Used for Welding (ECP 2001)
Process
Electrode Strength *
Chemical Composition
Weld
Position
RemarksMin. Yield
Stress
(t/cmP
2
P)
Min.
Tensile
Strength
(t/cmP
2
P)
Shield Metal
Arc
WELDING
(S.M.A.W.)
3.45 – 6.75 4.25 – 7.6
UElectrodeU: Low Carbon
UCoatingU: Aluminium, Silicon,
other deoxidizers
All weld
positions
Storage of
electrodes in
drying ovens
near the points is
a must.
Submerged
Arc
WELDING
(S.A.W.)
3.45 – 6.75
4.25 –
8.95
UElectrodeU: Medium Mn (1.0%)
Nominal Carbon (0.12%)
UFluxU: Finely powdered
constituents glued together with
silitales.
Flat or
horizontal
weld
position
-Fluxes must be
kept in storage.
-usually used in
shop.
Gas Metal
Arc
WELDING
(G.M.A.W.)
4.15 – 6.75 4.95 – 7.6
UElectrodeU: Uncoated mild steel,
dioxidized carbon manganese
steel
UShielding GasU: 75% Argon +
25% COR
2R or 10% COR
2
Flat or
horizontal
weld
position
CoR
2R is the least
shielding used in
buildings and
bridges.
Flux Cored
Arc
WELDING
(F.C.A.W.)
3.45 – 6.75 4.25 – 8.6
UElectrodeU: Low Carbon (0.05%
Max.)
UFluxU: Filled inside the electrode
core (Self Shielded)
All weld
positions
Useful for field
welding in severe
cold weather
conditions.
(*) The minimum value depends on the electrode type.
1.3.3 Bolts
Bolts used in bridge construction come in two general categories:
1. Ordinary Bolts: which are made from low-carbon steel. Example of
this type of bolts are grade 4.6 bolts. Because of their low strength,
they are not generally used in joints of main members. They should not
be used in joints subjected to fatigue.
2. High Strength Bolts: which are made from high strength alloy steels.
Examples of these bolts are grade 8.8 and 10.9 bolts. All high-strength
bolts carry markings on their heads to indicate the bolt grade; i.e., 8.8
or 10.9.
The usual bolt diameters used in bridge construction are 20, 22, 24, and 27
mm. The nominal values of the yield stress FR
ybR and the ultimate tensile
strength FR
ubR are as given in Table 2 according to ECP 2001. These bolt grades
are used in conjunction with structural components in steel up to St 52.

Steel Bridges
Table (2) (ECP 2001)
Nominal Values of Yield Stress FR
ybR and
Ultimate Tensile Strength FR
ubR for Bolts
Bolt grade 4.6 4.8 5.6 5.8 6.8 8.8 10.9
FR
ybR (t/cm2) 2.4 3.2 3.0 4.0 4.8 6.4 9.0
FR
ubR (t/cm2) 4.0 4.0 5.0 5.0 6.0 8.0 10.0

Ch1 Introduction (Steel Bridges تصميم الكباري المعدنية & Prof. Dr. Metwally Abu-Hamd)

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to Ch1 Introduction (Steel Bridges تصميم الكباري المعدنية & Prof. Dr. Metwally Abu-Hamd)

Similar to Ch1 Introduction (Steel Bridges تصميم الكباري المعدنية & Prof. Dr. Metwally Abu-Hamd) (20)

More from Hossam Shafiq II

More from Hossam Shafiq II (20)

Recently uploaded

Recently uploaded (20)

Ch1 Introduction (Steel Bridges تصميم الكباري المعدنية & Prof. Dr. Metwally Abu-Hamd)