Importance and Usage of Steel Hollow Sections

Steel hollow sections play a vital role in contemporary building construction, providing unparalleled strength while maintaining buildings lightweight. Produced in the three primary shapes—Rectangular (RHS), Square (SHS), and Circular (CHS)—these profiles find various applications ranging from skyscrapers to bridges and car chassis.

What Are Hollow Sections

Hollow Structural Sections (HSS) are steel structural shapes that have a hollow cross-section. In contrast to solid beams, HSS provides high load capability with reduced material, minimizing weight as well as cost. Its closed-section structure also improves torsion and buckling resistance.

Types of Hollow Sections

Rectangular Hollow Sections (RHS)

Characteristics and Fabrication

Rectangular Hollow Sections (RHS) have flat faces and right-angled internal and external corners, forming an elongated profile best suited for unidirectional loading. Their flat, smooth surfaces need little edge preparation before welding, reducing fabrication time and expense Usually made cold from steel coils, RHS starts life as slit strip rolled into a circular tube, welded longitudinally by electric resistance welding (ERW), then rolled through sizing rolls to flatten two opposite sides into an exact rectangle. The edges are developed gradually to two times the wall thickness in radius for balanced stress distribution and the convenience of welding.

Structural Behaviour:

The lengthened geometry focuses material where bending stresses are greatest, offering outstanding resistance to bending in one axis while being lightweight. This makes RHS an excellent option for building frames’ beams and girders that demand consistent bending action in a single plane. The enclosed section resists torsion more than open-web sections, minimizing deflections due to lateral loads.

Uses

• Bridge Spans & Overpasses: Girders of long span take advantage of RHS’s directional strength.
• Building Beams & Columns: Main load-carrying members in commercial and domestic buildings.
• Vehicle Chassis : Strength-to-weight ratio high, increases payload capacity without compromising safety.
• Industrial Racks & Frames: Lateral stiffness uniform carries heavy static loads.

Advantages

• Optimum Use of Material: Positioning of steel only where it is required minimizes weight by as much as 30% compared to solid sections.
• Weldability & Assembly: Flat faces facilitate fabrication, enables quick on-site construction.
• Cost Savings: Reduced transport and handling cost because of lower weight; reduced welding labor.
• Durability: Seal section prevents crevice corrosion and weathering.

Square Hollow Sections (SHS)

Characteristics and Fabrication

Square Hollow Sections (SHS) have the flat faces of RHS but equal side lengths, creating an equilateral square profile. Production repeats that of RHS: cold-forming steel strip to a round tube, ERW-welding, followed by sizing using four-v-shaped rolls to produce a square cross-section with equal wall thickness. Corner radii, again roughly twice the wall thickness, provide smooth stress transitions and allow automated fabrication.

Structural Behavior

With the same second moment of area about both principal axes, SHS offers isotropic bending stiffness in all directions, which makes it ideal for multi-directional loading conditions. Its symmetry in geometry offers equal performance under bending, axial, and torsional loading, leading to consistent, predictable deflections independent of load orientation.

Applications

• Structural Frames: Best suited for building frames where direction of loads changes, i.e., multi-story steel office buildings.
• Architectural Details: Decorative screens, balustrades, and structural features make use of SHS’s clean lines and modern appearance.
• Support Systems: Roof purlins, girts, and cross-bracing take advantage of the section’s multi-axis strength.
• Fencing & Gates: Consistent dimensions provide equal aesthetic appeal and structural integrity in security uses.

Benefits

• Multi-Directional Strength: Even properties in bending and torsion.
• Clean Appearance: Square profiles suit minimalist and industrial architectural themes.
• Fabrication Flexibility: Flat surfaces on all four sides ease welding and connection detail.
• Standardisation: Available in a wide range of sizes from 25×25 mm to 600×600 mm, with up to a 40 mm wall thickness.

Circular Hollow Sections (CHS)

Characteristics and Fabrication

Circular Hollow Sections (CHS), or steel tubes, start out as cold-formed circular tubes produced through ERW or submerged arc welding (SAW) for larger diameters. Precision sizing rolls check constant diameter and wall thickness. For hot-formed CHS, a cold-formed mother tube is rolled and heated to final size, conforming to stringent standards such as EN 10210 for hot-finished hollow sections.

Structural Behavior

The circular cross-section offers optimal distribution of material around the centroid. It maximizes torsional resistance while minimizing stress concentration. Thus, a CHS resists buckling uniformly along its perimeter, which is why it’s of interest in doing slender columns, pipelines, and structures that are subjected to dynamic loads or torsion or lateral loads.

Applications

• Columns & Piers: Uniform resistance of buckling in building supports and industrial racks.
• Trusses & Space Frames: Torsional rigidity enhances performance in lightweight roof structures and bridges.
• Pipelines & Conveyance Systems: Smooth internal surface for fluid flow; closed design prevents external corrosion.
• Architectural Structures: Fluid, curving forms in modern arches, canopies, and sculpture.

Advantages

• Bridge Spans and Overpasses: Long-span girders use RHS’s directional strength to their advantage.
• Beams and columns are the main parts of commercial and residential buildings that support loads.
• Chassis of the vehicle: High strength-to-weight ratio enhances cargo capacity without putting safety at risk.

Why Choose Steel Pipes and Tubes from AMMAN-TRY?

AMMAN-TRY Steel pipes and tubes can withstand heavy loads and harsh conditions, making them ideal for a variety of construction projects. We offer a comprehensive selection of steel pipes and tubes in various sizes, thicknesses, and grades to suit any application. Many of our steel pipes and tubes are treated with anti-corrosion coatings or come in naturally corrosion-resistant grades, ensuring longevity and minimal maintenance. The fire resistance property of Steel will provide an extra layer of safety in your buildings. Our team has extensive knowledge of steel products and their applications in construction. We can advise you on the best type of pipe or tube for your specific project requirements.