Design of Steel Structure
Lecture Note
COURSE CONTENTS
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Mechanical Properties of structural steel
Structural steel shapes
Tension members
Compression members
Bending members
Combined bending and compression members
Structural connections
COURSE OBJECTIVE
• Understand the fundamental principles behind
modern steel design code of practice
• Develop a basic understanding of various modes of
failure of skeletal steel members and a
comprehension of how these behaviors affect the
performance of steel structures.
• Develop technical competency in designing steel
members and connections using EBCS3,1995
Introduction
Engineering structures are required to
• support loads
• resist force
• transfer this loads and forces to the
foundation of the structure.
Introduction --• Structures that are designed by civil engineers
includes
• Buildings
• transmission towers
• storage vessels
• dams
• retainingwalls,etc
Introduction --Structures may be made from
• steel
• concrete
• wood
• aluminuim
• stone
• plastic etc,
or from combination of these.
Introduction --Steel structural members can be used for
• Frames -Indistrial&multi-storey building
• Truss-Bridge,buildings
• Plate Griders-bridge ,building
• Plate type strctures- bridge deck,shell,gas
holders and tanks
• Towers
Introduction --Structural members
Can be classified as
 tension or
 compression members,
 beams beam-columns,
 torsion members or plates according to the
method by which they transmit the forces in
the structures
Introduction ---
Introduction --Three overall objectives to be met if a structural
design is to be satisfactory:
• To provide structure to meet functional
requirement
• To select structural members and frames to
support loads
• To satisfy economic requirements
Introduction --Design Methods
• Allowable Stress Design(ASD)
• Plastic Design
• Limite State Design
Introduction --Material Behavior
Unlike masonry and concrete, which are weak in
tension, steel strong in both tension and
compression. Because of its high strength,
structural steel is widely used in construction.
• The most important properties of steel are yield
strength and ultimate strength, modulus of
elasticity ,shear modulus, Poisson’s, coefficient
of thermal expansion, and its density.
Stress-Strain Behavior of Structural Steel
Introduction --• Three types of structural steels are listed by
EBCS3.The yield stress of these steel ranges
from 235Mpa for Fe 360 steel to 355Mpa for
Fe 510 .As can be seen from table 1.1,the yield
stress of a given grade of steel is not a
constant. It varies with plate thickness, very
thick structural shapes and plates have
reduced yield stresses.
Introduction --Nominal value of yield strength fy and ultimate tensile strength f u for varies grades of steel
The code states that the following values for the elastic properties are to be used:
•Modulus of elasticity
E= 210Gpa
•Shear Modulus
G=80Gpa
•Poisson’s ratio………………………=0.3
•Coefficient of thermal expansion
=12 x 10-6 per oC
•Unit mass
=7850Kg/m3
Introduction --1.6 Structural Steel Shapes
A structural steel can be a rolled shape or can be
built-up from two or more rolled shapes or
plates connected t by welds or bolts.
Introduction ---
a)Rolled Section
b)Compound sections
c) Built-up Sections
Fig.1.2 Structural steel Shapes