By BYJU'S Exam Prep

Updated on: September 25th, 2023

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 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.

What is Structural Steel?

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.

Structural Steel Definition

Structural Steel is Steel that contains carbon, not more than 2.1%. These are also called Carbon Steel, and structural Steel typically has a carbon content of less than 0.6%.

Download Formulas for GATE Civil Engineering – Structural Analysis

Properties of Structural Steel

The features of structural steel influence the design and construction of steel structures, and the value of different steel characteristics are highlighted below. The various tests that produce the importance of mechanical properties of structural Steel and the desired values of each parcel have been discussed in this article.

• 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.
• Specific heat: The amount required to raise an object’s temperature by a particular quantity is known as specific heat or heat capacity. A higher specific heat value indicates that the thing is more insulating. The units of measurement are Joules per Kilogram Kelvin. Specific heat for carbon structural steel ranges from 450 to 2081 J/kg-K, while for structural alloy steel, it ranges from 452 to 1499 J/kg-K.

Download Formulas for GATE Civil Engineering – Geotechnical Engineering

Types of Structural Steel

Carbon is the most often used commercial steel alloy. Increased carbon content improves hardenability and boosts hardness and strength. Conversely, carbon increases brittleness and lowers weldability because of its propensity for forming martensite. As a result, the carbon content in commercial Steel can be both a blessing and a burden. Based on the carbon content, the mechanical properties of different types of structural Steel and their uses are given below:

• Carbon steel: Steel in which the carbon content is upto 2% is known as carbon steel. The Specified ultimate tensile strength is 410 to 440 MPa, and the yield strength is 350 to 400 MPa.
• High-strength carbon steel: These steels are used in structures such as transmission lines and microwave towers. The specified ultimate tensile strength is 480 to 550 MPa, and the yield strength is 350 to 400 MPa.
• Medium and high strength micro-alloyed steel: Alloys such as chromium, nickel, molybdenum, etc., are used to increase the strength while retaining the desired ductility. The specified ultimate tensile strength is 440 to 590 MPa, and the yield strength is 300 to 450 MPa.
• High strength quenched and tempered Steel: Heat treatment increases strength in this type of Steel. The specified ultimate tensile strength is 440 to 590 MPa; the yield strength is 300 to 450 MPa.
• Weathering Steel: These are corrosion-resistant Steel and are often not Painted. The specified ultimate tensile strength is 480 MPa, and the yield strength is 350 MPa.
• Fire-resistant Steel: These steels are also known as thermo mechanically treated (TMT) steel and are used where the structures are more prone to fire.

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

Rolled Steel I- sections

Used as beams or columns.

Beams

• ISJB – Indian Standard Junior Beam
• ISLB – Indian Standard Light Beam
• ISMB – Indian Standard Medium Beam
• ISWB – Indian Standard Wide Flange Beam

Columns/Heavy weight beams

• ISSC – Indian Standard Column Section
• ISHB – Indian Standard Heavy Beam

Rolled Steel Channel Sections

Used in steel-framed structures, steel bridges, crane girders

Categories

• ISJC – Indian Standard junior channels
• ISLC – Indian Standard lightweight channels
• ISMC – Indian Standard Medium Weight Channel.
• ISMCP – Indian Standard Medium weight parallel flange channels

Rolled Steel T – Sections

Used to form built-up sections and as members of steel roof trusses.

Categories

• ISNT – Indian Standard Normal Tee Bars
• ISHT – Indian Standard Wide flange Tee Bars
• ISST – Indian Standard Long Legged Tee Bars
• ISLT – Indian Standard Light Tee Bars
• ISJT – Indian Standard Junior Tee Bars

Rolled Steel Angle Sections

Used in the construction of roof trusses and filler joist flooring.

Categories

• ISA – Indian Standard Equal Angles
• ISA – Indian Standard Unequal Angles
• ISBA – Indian Standard Bulb Angles

Rolled Steel Bars

Used as reinforcement in concrete and steel grill work, among other things.

ISRO – Indian Standard Round Bars

Rolled Steel Tubes

Used in tubular trusses as columns, compression members, and tension members.

Rolled Steel Flats

Lattice bars made of rolled steel flats are used to connect the elements of built-up columns.

Rolled Steel Sheets

These are used in automobiles, appliances, furniture, and other everyday items.

Uses of Structural Steel

Structural Steel is the most widely used engineering and building material on the planet and is commonly used in modern construction. Because of its constructability and high strength-to-weight ratio, Structural Steel is used to build today’s highest structures.

Concrete, on the other hand, has a substantially lower strength-to-weight ratio than Steel, although being less dense. This is owing to the considerably larger volume necessary for a structural concrete element to hold the same weight; Steel, although denser, requires less material to carry the same load.

Building Works

• Used as a structural component in trusses, beams, and other steel structures.
• Grills, doors, windows, and other non-structural materials
• In steel pipelines, tanks, and other similar structures.
• Used in sanitary and sewer fittings, rainwater items, and so on.
• The sheets are made of corrugated cardboard.
• Used as concrete reinforcement.

Reinforcement Works

Since the concrete is strong in tension and weak in compression, Steel is used as reinforcement to increase the tensile strength of the concrete structure.

Composition of Structural Steel

The chemical compositions influence the properties of Structural Steel. Some chemical elements used to enhance the mechanical properties are listed below. Structural Steel is a mixture of iron and other metals. Some parts are purposefully added to iron to achieve specific properties and features; the various compositions have been discussed in the following:

• Carbon: One of the most significant chemical ingredients in Steel is carbon. Carbon concentration rises, resulting in a material with less flexibility and more strength.
• Chromium: Small levels of chromium are present, combined with copper and nickel, to strengthen the material’s corrosion resistance.
• Manganese: Manganese, along with oxygen and sulphur, is employed as a neutralizer in the hot rolling of Steel, and it has effects on the material properties of steel grades that are similar to those of carbon.
• Aluminum: Aluminum is a key deoxidizer that contributes to forming a finer-grained crystalline microstructure.
• Copper: Copper is used to promoting corrosion resistance.
• Sulphur and phosphorus: Sulphur and phosphorus are often limited in steel alloys because they negatively impact the Steel’s durability and strength.
• Molybdenum: Molybdenum increases the Steel’s strength at high temperatures and its corrosion resistance.

Best Books for Design of Steel Structures

Here is the list of best books to prepare the Steel Structures required for candidates preparing for GATE CE 2023.

• Design of Steel Structures by S.K.Duggal
• Design of Steel Structures by N. Subramanian
• Design Of Steel Structures by L Negi

As an engineer or architect, you rely on structural steel for many applications. Steel's strength, durability, and malleability have made it integral to building construction and infrastructure. To properly specify, design, and inspect steel structures, you need an in-depth understanding of steel's properties, composition, and applications.

Steel is an alloy of iron and carbon, but modern steel often contains other elements to improve its properties. By controlling the amounts of these elements, steelmakers can produce steel with a wide range of strengths, hardness, and other characteristics. The properties of a particular steel depend on its chemical composition and how it is processed. Steel's versatility allows it to be used for beams, columns, trusses, plates, pipes, and nearly every other building component. When it comes to structural steel there are also different types of structural steel grades suitable for different construction projects.

This article provides an overview of structural steel for professionals who work with it. You will learn about steel production, properties, composition, shapes, and common applications. With this knowledge, you can make optimal use of steel for your next project. Steel has been the backbone of construction for over a century, and understanding its fundamentals is key to building innovative and cost-effective structures.

What is Structural Steel?

Structural steel is a strong, durable and versatile construction material used in buildings, bridges, and other structures. It is an alloy of iron and carbon that is produced by heating iron ore and other elements in a blast furnace.

Structural steel comes in a variety of shapes, sizes, and strengths that can suit the needs of any construction project. The most common shapes are wide flange beams, angles, channels, hollow structural sections, and plates. These shapes are produced in a range of standard sizes, but can also be fabricated into custom shapes and sizes.

The strength of structural steel depends on its carbon content and any alloys. The most common grades are A36 and A572, which have yield strengths of 36,000 and 50,000 pounds per square inch (psi), respectively. Higher-strength, lower-alloy steels include A514 and A588. Structural steel can also be galvanized or stainless for corrosion resistance and weathering steel for atmospheric corrosion resistance.

Structural steel offers many benefits for construction:

1. High strength-to-weight ratio, allowing for large spans and high loads
2. Easily welded and bolted for connections
3. Can be pre-fabricated for efficient on-site assembly
4. Recyclable and reusable material
5. Non-combustible, which improves fire safety

With its exceptional properties, structural steel has become the premier construction material for building the world’s infrastructure and skylines. It continues to enable innovative and sustainable building designs in modern architecture.

Structural Steel Channel 80x40 UPN(L) x6mm

Chemical Composition and Mechanical Properties of Structural Steel

To understand structural steel, you must first comprehend its chemical composition and mechanical properties.

• Chemically, structural steel contains iron, carbon, and other elements like manganese, phosphorus, sulfur, and silicon in varying amounts depending on the grade. The carbon content usually ranges from 0.15 to 0.30% and determines the strength and hardness. More carbon means higher strength and hardness but lower ductility.

• The mechanical properties refer to a steel's strength, hardness, toughness, ductility, and elasticity. Strength is the ability to withstand external forces without breaking or deforming permanently. Hardness measures resistance to surface deformation. Toughness indicates the energy absorbed before fracturing, while ductility refers to the degree of permanent deformation before fracture. Elasticity is the ability to return to the original shape after stress removal.

• There are many grades of structural steel with different mechanical properties to suit various applications. Higher-strength, lower-alloy steels like ASTM A36 and ASTM A572 Grade 50 are often used in construction. Even higher-strength, lower-alloy steels include ASTM A913 Grade 65 and ASTM A992. Stainless steels, like 304 and 316, provide corrosion resistance for architectural facades and trim.

In summary, by controlling the chemical composition, especially the carbon content, and alloying elements, the mechanical properties of structural steel can be adjusted to meet the strength, ductility, hardness, and toughness requirements for applications like buildings, bridges, and sculptures. With proper selection of grade based on service conditions, structural steel can provide an economical and sustainable solution.

Structural Steel Sheet Pile 12mm Hellog

Common Shapes and Sizes of Structural Steel

Common Shapes

The most common shapes of structural steel are:

• I-beams: I-beams, also known as H-beams, are shaped like the letter I. They are very efficient at supporting heavy loads over long spans. I-beams are commonly used in floor beams, roof beams, and columns.

• Angles: Angles are L-shaped and are used primarily for bracing, framing, and reinforcing. They are also used extensively in steel bridges, buildings, and towers.

• Channels: Channels are U-shaped and are often used for bracing, framing, and reinforcing. They are also commonly used in steel bridges, buildings, and towers.

• Hollow structural sections: Hollow structural sections, or HSS, are hollow tubes used extensively in steel structures. They are highly efficient and provide maximum strength with minimum weight.

• Line pipe: It is a type of pipe that is manufactured from high strength carbon steel. It is typically made according to metallurgical specifications that were developed by the American Petroleum Institute (API). Line pipe can be used to build pipelines that transport a variety of resources including natural gas, oil, petroleum, and water.

• Steel plate: Structural steel is a type of carbon steel with a carbon content of up to 2.1% by weight. Structural plate is typically used for making construction materials and structures where weight savings and durability are both important factors.

Standard Sizes

Structural steel shapes are produced in a variety of standard sizes. The sizes are specified by their depth, flange width, web thickness, and weight per linear foot. For example, a W12x65 I-beam is 12 inches deep, has a flange width of 65⁄8 inches, a web thickness of 0.405 inches, and weighs 65 pounds per linear foot. The most common sizes are between W6x9 and W36x730 for I-beams and between C3x4.1 and C15x50 for channels.

Structural steel is available in a range of sizes to suit the load requirements of any application. By selecting the appropriate shape and size, structural steel can be optimized to provide maximum strength with minimum weight. The common shapes and standard sizes of structural steel make it ideal for use in steel construction.

Structural Steel H-beam 160 IPE 6x3 Hellog

Welding processes suitable for Structural Steel

Welding is a crucial process for joining structural steel components. Several welding methods are commonly used, each with its own set of advantages and disadvantages depending on the application.

Arc Welding

The most common types of arc welding are shielded metal arc welding (SMAW), gas metal arc welding (GMAW), and flux-cored arc welding (FCAW). In arc welding, an electric arc forms between an electrode and the base metal, melting both and forming a weld pool that cools to form a joint. Arc welding is versatile and can be used in all positions.

• SMAW uses a flux-coated electrode to shield the weld pool from air. It requires more skill but can weld in windy, outdoor conditions.
• GMAW uses an inert gas to shield the weld pool. It has a high deposition rate, good quality, and can be automated.
• FCAW also uses a gas to shield the weld pool. It works well in windy conditions and has a high deposition rate.

Resistance Welding

In resistance welding, metal pieces are heated by passing an electrical current through them. The heat melts the metals, which then fuse together under pressure. The most common types are spot welding and seam welding. Resistance welding is fast, limited distortion, and can be automated. However, it requires high electrical power and close fit-up between parts.

Other Welding Methods

Other less common welding methods for structural steel include oxyfuel welding, laser beam welding, and electron beam welding. These provide deep penetration but require an inert gas shield and vacuum chamber, respectively. They are often limited to automated or robotic welding in controlled environments.

The appropriate welding technique depends on factors like material thickness, joint design, welding position, and production volume. Proper welding procedure and quality control help ensure strong, durable welded connections in structural steel assemblies.

Common Applications of Structural Steel

Structural steel has many common applications due to its strength, durability, and malleability.

Building Construction

Structural steel is commonly used in the construction of buildings. Steel beams and columns provide structural support for high-rise buildings, warehouses, and commercial spaces. Steel framing is also popular for constructing building exteriors and interiors.

Bridges

Steel is an ideal material for bridge construction. Steel trusses, beams, and girders are commonly used to build roadway and railway bridges. Steel bridges provide strength and durability to withstand vehicle traffic and environmental conditions. Famous examples of steel bridges include the Golden Gate Bridge and Brooklyn Bridge.

Transportation Infrastructure

In addition to bridges, structural steel is used for other transportation infrastructure like railways, airports, and shipyards. Steel rails, beams, and trusses are used for railway tracks and train stations. Steel framing provides the structural support for airport terminals, hangars, and control towers. Steel plates and beams are also used in shipbuilding and port construction.

Industrial Applications

Structural steel has many applications in industrial settings. It is used for building factories, warehouses, and equipment. Steel beams provide the structural framework for industrial buildings. Steel plates and beams are also used to construct storage tanks, silos, cranes, and conveyor systems commonly found in factories and warehouses.

In summary, structural steel is a versatile material with many applications in building construction, transportation infrastructure, and industrial equipment. Its properties of high strength, durability, and malleability allow it to be used for a wide range of structures and components that are integral to modern society.

Learn more: Steel vs. Concrete: Which Material Reigns Supreme for Construction in Nigeria?

Conclusion

As you have learned, structural steel is a fundamental material used in construction and engineering applications. With a versatile range of properties, steel alloys provide strength, durability, and design flexibility for buildings, bridges, and infrastructure. By understanding the composition, properties, and applications of the various steel grades, you can make informed decisions in your projects and ensure the material is suitable for the intended use.

Steel has been a crucial part of human progress for centuries and will likely continue to shape the built environment for generations to come through continuous innovation. With this foundational knowledge, you are now better equipped to work with this essential material.