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What Is Hollow Section and How Is It Used in Construction?

hollow section

Table of Contents

A hollow section is a steel structural profile with a closed cross-section and an empty core, engineered to carry heavy loads while keeping weight low. Builders rely on these structural hollow sections to shape stadiums, bridges, and the streamlined towers that define modern skylines.

Next, this guide walks through the main types of hollow sections, where they show up in real projects, and the international standards that govern them.

Main Types of Hollow Sections

Hollow sections come in three core shapes: circular, square, and rectangular. Each geometry suits a different structural challenge, and choosing correctly affects both performance and cost.

Deep Dive: Want to know how structural hollow sections differ from standard pressure-rated vessels? Check out our comprehensive guide on What Is A Structural Pipe? Selection & Standards.

CHS (Circular Hollow Sections)

CHS profiles carry a round, tube-like cross-section with no flat faces. The shape spreads stress evenly around the perimeter, so these members offer uniform strength in every direction and resist torsion and buckling exceptionally well.

SHS (Square Hollow Sections)

SHS profiles use four equal sides with flat faces. The symmetrical shape looks balanced from any viewing angle, and the flat surfaces simplify connections, cladding, and fabrication.

RHS (Rectangular Hollow Sections)

RHS profiles share the flat-faced design of SHS but use unequal sides. The deeper profile concentrates bending resistance along the major axis, so it carries directional loads efficiently.

hollow section

Real-World Applications of Hollow Sections

Each profile finds its own niche on the job site, where shape meets purpose.

CHS shines in large transport hubs. For instance, the soaring roof trusses of major airports and rail terminals often use circular sections to create lightweight, elegant spans. Offshore wind farms depend on them too, since CHS monopiles and jacket structures stand up to crashing waves and constant cyclic stress.

SHS performs beautifully in space frames and modular construction, where repeating units must bolt together quickly and cleanly. Designers also favor squares for exposed columns, since the clean profile suits visible architectural work.

RHS, meanwhile, suits beams, curtain wall supports, and long horizontal spans. The flat sides also make it easy to mount glazing systems and façade panels, so rectangular tubes appear throughout modern building envelopes.

For projects requiring high bending resistance and efficient load-bearing, sourcing certified Square and Rectangular Pipes (SHS/RHS) is critical to ensuring structural integrity.

Key Technical Standards and Steel Grades

International standards make sure every hollow section meets strict requirements for dimensions, strength, and quality. Buyers working outside the United States typically specify European, Australasian, or Japanese codes, and knowing the differences prevents costly mistakes.

The European framework leads with two key documents. EN 10210 covers hot-finished structural hollow sections, while EN 10219 governs cold-formed welded versions. Both commonly specify the S355 grade, a high-strength steel with a minimum yield strength of 355 MPa that balances performance and weldability. Many projects also call for the lighter S275 grade where loads stay moderate.

Beyond Europe, regional codes carry equal weight. Australia and New Zealand rely on AS/NZS 1163, which sets grades such as C350 and C450 for cold-formed structural sections. Japan, meanwhile, applies its JIS G3466 standard for general-structure square and rectangular tubes. Each system regulates physical wall thickness directly, so dimensions stay consistent and predictable.

Note for Buyers: Because structural standards regulate physical wall thickness rather than nominal bore, terminology matters. Read our analysis on Steel Pipe vs. Tube: Key Differences in Size & Application to avoid RFQ mistakes.

FAQs

Should I leave a hole at a hollow section?

Yes, you usually should, especially before hot-dip galvanizing. Vent and drain holes let molten zinc flow through and let trapped air and moisture escape, which prevents internal corrosion and stops a sealed tube from bursting when heated. Engineers still place these holes carefully so they do not weaken the member.

What is the difference between hollow section and I-beam?

The difference comes down to shape and load behavior. A hollow section uses a closed tube profile that resists twisting in every direction, so it shines as a column. An I-beam concentrates steel in its flanges, so it carries bending loads in one plane and bolts together easily. As a result, engineers favor I-beams for floor beams and hollow sections where torsion or appearance matters.

What are the 7 types of construction?

One common way to group construction projects is into seven types, sorted by purpose and scale:

  1. Residential, such as houses and apartments.
  2. Commercial, including offices and retail centers.
  3. Industrial, such as factories and warehouses.
  4. Heavy civil and infrastructure, like bridges and highways.
  5. Institutional, covering schools and hospitals.
  6. Specialized and green, spanning renewable energy and modular builds.
  7. Mixed-use, blending homes, retail, and transit in one project.

Hollow sections appear across nearly all of these, which underlines their versatility.

hollow section

Conclusion

Hollow sections have earned their place as a cornerstone of modern construction. They merge economy, strength, and material efficiency, letting designers build lighter frames that use less steel and demand less upkeep. Because they cut the amount of material a structure needs, they also help lower its embodied carbon. Whether the goal is a graceful stadium roof or a robust offshore platform, this versatile profile delivers measurable value.

About Baolai Pipes

Founded in 1991, Baolai (Tianjin Baolai Steel Group) exports steel pipes to over 150 countries and produces CHS, SHS, and RHS sections to EN, BS, and JIS standards. Visit Baolai Pipes to browse the range or request a quote.

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