Structural steel is one of the most widely used materials in commercial and industrial construction. How come?
With high strength, good machinability, and high ductility, structural steel plate is a safe and cost-effective building material that serves as the backbone of structural steel buildings. This article examines what makes structural steel such an advantageous building material, the different types of structural steel, and the different types of metal grades and their corresponding properties.
Structural steel is a versatile type of carbon steel. By weight, structural steel has a carbon content up to 2.1%. American Society for Testing and Materials, ASTM International, sets standards for composition and dimensional tolerances for all structural steel grades.
If you’d like to speak to qualified experts who care about your structural steel buildings project, contact us now. Kloeckner Metals combines a national footprint with the latest fabrication and processing technologies and most innovative customer service solutions.
When weight savings and durability are both key construction factors, steel plates will likely be used. In addition to structural steel plates, structural steel comes in a variety of shapes making it adaptable for diverse projects.
Structural steel beams are the basis for thousands of residential and commercial constructions, vehicle bed framing, bridges, and machine bases. The universal, or I-beam has a top and bottom, called flanges (sometimes, legs). Often these flanges taper. The middle section of the beam is called the web. The web is built to resist blunt force, while flanges resist bending.
The H-beam is heavier than the universal I-beam, with greater force tolerance. Their edges do not taper.
T-beams have a T-shape, like the universal beam but without a bottom flange. Lacking a flange makes the T-beam less versatile, due to lower tensile strength. Therefore, they are more often used in reinforcement.
Channels are designed like I-beams, where the flanges are split vertically down the web. This creates one flat face with parallel flanges. The flat faces allow channels to be bolted up to other flat faces.
C-channels have a slight slope on the inner flange surface. They are not typically applied as primary load bearing beams. Rather, they provide a great amount of structural support, most useful as frames and for bracing.
Bearing piles are similar to I-beams in that they have the same shape. However, bearing piles have uniform thickness across all sections. They are primarily used to support vertical loads.
H-piles are often placed in the ground to provide deep foundation support for superstructures.
Structural steel angles have various applications, ranging from everyday uses—in chairs, and bed frames—to warehouses and power towers. A steel angle is a steel bar that has an L-shaped cross section, forming a 90 degree angle.
L-shapes may have leg lengths that are equal or unequal. Both are great for reinforcement.
Hollow structural section (HSS) refers to high-strength welded steel tubing. They are produced in round, square and rectangular shapes and support multidirectional load bearing. As the name suggests, regardless of shape, the mid-sections are hollow.
Significant to all structures is their potential to absorb energy. There are three important mechanical properties that support structural steel’s wide-ranging functionality:
Yield strength refers to the minimum force required to achieve permanent deformation. Yield strength is determined with a tensile test, at the first point of deviation from proportionality on a stress-strain curve. Load-bearing steel should have a yield strength greater than 35,000 psi. Steel framing and non-load bearing material has a minimum yield strength requirement of 33,000 psi.
Tensile strength is known as the ultimate, or maximum stress that a material can withstand before permanent failure. If yield strength is the first point at which a material permanently bends, tensile strength denotes the point at which the material breaks. Tensile strengths have dimensions of force per unit area, commonly expressed in units of pounds per square inch (psi). 36,000–50,000 psi is considered ordinary tensile strength for structural steel, but can reach up to 58,000–70,000 psi.
Elongation is the degree of elasticity before rupture. The greater a material’s tensile strength, the less it will elongate under stress. Whether a material is bent, stretched, or compressed, elongation will be a point between tensile strength and yield strength and is expressed as a percentage of its original length. There is no elongation requirement for non-structural steel.
Structural steel buildings require certain constructibility considerations. Are materials durable? Sustainable? What will happen to the material under impact caused by extreme weather conditions? How cost-effective and easy to work with is the building material?
Structural steel satisfies all of these use assessments.
Because a strength to weight ratio indicates how useful the material is for its weight, use assessments for construction tend to prioritize high strength to weight ratio. Structural steel is not just strong, but it is relatively light weight. It is known for its ratio of high strength to low weight, making it easier to use and cheaper than other metals.
Another advantage of structural steel is good machinability. A free machining material requires minimum power to cut, can be cut quickly, easily obtain a good finish, and does not wear down the tooling. Again, this benefits project ease across economical concerns—saving time with minimal risk for tool damage and repair.
An especially relevant consideration for building construction is ductility. Ductility describes the ability of a material to be drawn or deformed without fracture. In earthquake engineering, ductility is the term used to identify how well a building withstands displacements imposed by ground shaking. So, if you want a building to be earthquake ready, you want a material that has a properly detailed steel frame with a degree of elasticity that will enable it to tolerate large deformations before the onset of failure (fracturing). As we consider structural steel grades, keep in mind that an increase in carbon will increase the strength but decrease the ductility.
Did you know that steel is the most recycled material in the world? This is another distinct advantage of steel. Steel is continuously recyclable, which means it can be recycled indefinitely without compromising quality.
Structural steel brings greater value to a project by having lower initial costs and fewer risks than other building materials. Its ease of use, versatility, and strength to weight ratio all mean lower costs, which has a big bearing on the overall cost of construction.
The Charpy impact test calculates the amount of energy that can be absorbed by a specific material, such as metals, ceramics, and polymers and is used to grade its deterioration. It is a widespread evaluative test indicating the relative toughness and quality of a material. The Charpy or pendulum impact test continues to be used as an economical quality control method and helps to determine whether a material is suitable for a given project.
This test consists of striking a notched sample specimen with a hammer on a pendulum arm. The specimen is held securely at each end while the hammer strikes opposite the notch. Measuring the decrease in motion of the pendulum arm indicates the energy absorbed. It’s important to note that the toughness of a material may vary based on impact under low-temperature conditions, and additional stress concentrators such as notches and cracks.
A36 is a widely preferred and versatile low-carbon low-cost steel known for its yield strength (36,000 psi) and excellent machinability. A36 can elongate to about 20% of its original length, and is commonly used for columns, beams, decking and finish elements. While it has decent ductility, A36 steel is not used for reinforcement.
A572 is a high-strength low-alloy steel (HSLA) steel plate. This weldable, low-alloy structural steel has similar yield and tensile strength to A36 steel, but is better suited for applications that require higher strength per weight ratio. Without sacrificing strength, A572 is lighter than the equivalent made with carbon steel, making it a great material for transmission towers, roller coasters, and bridges.
A588 steel has a yield and tensile strength greater than 46,000 psi, higher than both A36 and A572. With similar elongation, A588 differentiates in its superior atmospheric corrosion resistance, leading to a longer life cycle. Therefore, A588 meets the specific needs of industries requiring outdoor solutions.
A514 is a quenched and tempered alloy steel with a yield strength of 100,000 psi and an elongation between 16-18%. A514 is a high-performance structural steel, providing good weldability, and toughness at low atmospheric temperatures. Primarily, A514 is used to support heavy loads, in cranes and other high wear machine applications.
Approximately 25% of buildings are made up of structural steels. This can take the form of steel frames, beams, columns, bars, and plates. Now you know why!
If you’d like to speak to qualified experts who care about your structural steel buildings project, contact us now. Kloeckner Metals combines a national footprint with the latest fabrication and processing technologies and most innovative customer service solutions.
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