UNIT 1
Structural Steel is a fantastic building and construction material. There are numerous reasons
why it is so frequently used around the world. Structural steel is both reliable and adaptable. In
this article, we will study structural steel’s properties, types, compositions, and uses.
Structural steel has several applications in today’s society, but the building is the one most
closely linked with it. Steel is one of the most important building materials, chosen for various
reasons, the most important are its adaptability, higher strength, more economical, rapid
construction, easy repair or modification, high quality, and reliability.
Structural Steel is a special kind of Steel. It is used for construction purposes. Due to its rigidity
and high strength-to-weight ratio, structural Steel is mainly employed in buildings. Structural
Steel is used in houses, warehouses, airplane hangars, educational facilities, bridges, stadiums,
etc.
Properties of Structural Steel
The physical properties of steel include high strength, durability, ductility & corrosive resistance.
The mechanical properties of steel include hardness, tensile strength, yield strength, plasticity, &
creep.
Density: The density of Structural Steel is 7750 to 8100 kg/m3.
Young’s Modulus of Elasticity: Typical values for structural steel range from 190-210
GPa
Poisson’s ratio: For structural Steel, the acceptable value ranges from 0.27 to 0.3.
Tensile strength: Structural Steel has high tensile strength, so it is preferred over other
construction materials.
Yield strength: The yield strength, also known as the yield point, is the stress at which
an object permanently deforms. When stress is removed, it does not revert to its former
shape. Carbon structural steel has a yield strength ranging from 187 to 758 MPa. The
values of structural Steel constructed of alloys range from 366 to 1793 MPa.
Shear strength: The shear strength of steel structure is specified at the failure under
shear stress, and it is about 0.57 times the yield stress of structural Steel.
Hardness: The resistance of an object to shape change when force is applied is referred
to as hardness. There are three different types of hardness tests. Scratch, indentation, and
rebound are all terms used to describe the process of scratching and indenting, and the
hardness of structural Steel manufactured with alloys ranges from 149 to 627 kg. Carbon
structural steels have a weight range of 86 to 388 kg.
Melting point: Because there are so many different types of structural Steel, there is no
standard melting point.
Types of Steel Sections
Structural steel members are fabricated in factories according to their intended use. Continuous
casting molds are used to cast rolled steel parts with no joints. The following sections describe
the various shapes and forms of rolled steel sections.
1. Rolled Steel I-sections (Beam sections).
2. Rolled Steel Channel Sections.
3. Rolled Steel Tee Sections.
4. Rolled Steel Angles Sections.
5. Rolled Steel Bars.
6. Rolled Steel Tubes.
7. Rolled Steel Flats.
8. Rolled Steel Sheets
Advantages
1. Durability: Steel is incredibly durable. It is very resistant to corrosion and can last for
decades in the right conditions. Steel is also fire-resistant and won’t rot or decay like
other materials.
2. Strength: Steel is solid. It has an incredibly high tensile strength and can withstand a
large amount of pressure and weight. It makes it great for structural applications and
ensures that used in a wide range of projects.
3. Cost-effective: Steel is much more cost-effective than other materials. It is cheaper to
manufacture than other materials, and because it is so durable, it won’t need to replace.
4. Versatility: Steel is incredibly versatile. It can use in many applications, from residential
to commercial. It is also available in various sizes, shapes, and finishes, making it
suitable for many projects.
5. Eco-Friendly: Steel is an eco-friendly material. It means that it is a much more
sustainable option than other materials.
Disadvantages
1. High Cost: Steel is usually more expensive than other building materials due to its
strength and durability, and the production process requires a lot of energy and raw
materials.
2. Corrosion: Steel is vulnerable to rust and corrosion, especially when exposed to air or
ground moisture. A protective coating or sealant must protect the metal from rust.
3. Weight: Steel is much heavier than other building materials, making it difficult to
transport and install. It can be a disadvantage when working in a confined area or on a
limited budget.
4. Heat Conductivity: Steel is an excellent conductor of heat, which can lead to thermal
bridging in buildings. It means that heat can escape easily through steel walls, leading to
an overall decrease in energy efficiency.
5. Maintenance: Steel requires regular maintenance to prevent corrosion and rust.
Shape Factor
Limit State Method
Limit states are the states beyond which the structure no longer satisfies the performance requirements
specified. The limit states are classified as: a) Limit state of strength; and b) Limit state of serviceability.
