Structural Steel Buildings

Before steel was introduced in the mid-19th century, large buildings were made of wood, stone, and brick. But with the Industrial Revolution came improvements in metallurgy, and steel could be mass-produced and cheaply.

This led to the construction of the first steel-framed buildings, such as Chicago’s Home Insurance Building, which was built in 1885 and was the first skyscraper.

Since then, steel has evolved. High-strength, low-alloy steel, improved welding and fabrication procedures, and developments in corrosion protection have all made steel more suitable for modern buildings.

Structural steel is divided into classes, each with mechanical properties, such as strength, ductility, and composition, determined by specified criteria.

Common grades:

The following are the most commonly used grades in building construction as classified by the American Society for Testing and Materials (ASTM) standards.

1. ASTM A36 is a popular grade with high weldability and ductility, making it ideal for SS beams, columns, and other construction applications.
2. ASTM A572 is a high-strength, low-alloy steel suitable for high-stress constructions such as bridges and towers. It is stronger than A36, allowing for lighter structures that still perform well.
3. A992 steel is ideal for wide flange beams because of its high strength, weldability, and fracture resistance. These properties make it preferred for many high-rise buildings and other large constructions.
4. ASTM A500 is a flexible grade commonly used in structural applications, especially for hollow structural sections (HSS), and is widely used in columns and other load-bearing structures.

Types of steel in construction

The main types based on form and application in construction are:

• Carbon steel: The most basic type used for general construction. It provides a good balance of strength, affordability, and weldability.
• High-strength, low-alloy steel: This type of steel is stronger and longer-lasting than standard carbon steel, so it’s perfect for projects that require high structural strength.
• Corrosion-resistant or weathering steel is used in structural steel erections exposed to harsh environmental conditions.

Steel shapes and beams form the backbone of modern construction, offering engineers and architects a versatile toolkit for building design.

These standardized sections, including wide-flange beams, channels, angles, and specialty shapes, are manufactured through hot-rolling processes to meet precise dimensional and strength requirements for various load-bearing applications.

The process starts with the framework, sometimes called the steel frame. This framework is the building’s “skeleton,” composed of many interconnected parts.

Primary framing components include:

• Beams: Horizontal steel members that carry loads across the steel structure.
• Columns: Vertical steel members that transfer the weight of the building to the foundation.
• Bracing systems consist of diagonal steel members or steel cables that provide lateral support and resist forces such as wind and seismic activity.
• Floor and roof systems include steel decking and joists, which form the base of the floors and roofs.

Column and beam connection

Depending on the design and required strength, columns and beams are connected by bolts or welds. These connections are critical to the structure's overall stability and must be made precisely to maintain structural integrity.

Bracing systems

Bracing systems strengthen steel frames against lateral forces like wind and earthquakes. They can be built using cross-bracing or moment-resisting frames.

Floor and roof systems

Steel decking is used to construct the floors and roofs of steel-framed buildings. Steel joists support these decks, distribute loads to the structure, and serve as a base for the concrete slabs.

Framing installation process

Here’s a step-by-step guide to the building erection process:

• Site and foundation preparation: Level the construction site before laying the foundation.
• Column installation: Install steel columns from the corners inward.
• Beam and bracing installation: Connect beams to columns and bracing.
• Frame the floor and roof: Use steel joists to support floors and roofs, with steel decking on top.
• Check alignment and adjust: Check the steel frame’s alignment and make the necessary adjustments to achieve balance.

Design and engineering

A thorough design for the steel building is produced before engineering and manufacturing. Engineers work with architects and contractors to produce structural drawings that specify the type and location of the metal studs. These drawings must also include the building’s purpose, load requirements, safety regulations, and environmental considerations.

Fabrication

Once the design is complete, the steel components are produced in a steel manufacturer’s facility. This involves cutting, shaping, and welding the steel components to meet the project’s requirements.

Erection and assembly

The components are then delivered to the site, and the erection process starts. The building structure is built by first erecting steel columns and beams. These are connected by welding or high-strength bolts.

Quality control and safety

Strict quality control (QAC) is implemented throughout to ensure that every weld, bolt, and beam meets safety and performance requirements. Inspections are done regularly to check for weld strength, material defects, and proper alignment. Workers must also follow strict safety measures to prevent accidents.

Commercial and office buildings. Steel can handle huge loads with small cross-sections, so open floor plans are possible in office buildings and taller structures like skyscrapers.

Industrial facilities and warehouses require large open spaces that can withstand heavy machinery in environments where steel is a good option.

Residential structures. Steel is resistant to natural forces like severe storms and earthquakes, has a longer life, and requires less maintenance than conventional materials.

Infrastructure projects: Bridges, airports, and stadiums require materials that can withstand heavy loads and extreme weather conditions. Steel is often preferred because of its flexibility, strength, and durability.

Benefits of weld-up construction

• Strength-to-weight ratio: Steel is strong for its weight, but it requires less material to support a building’s loads than concrete or wood.
• Clear-span interiors. Like other PEMBs, weld-up buildings do not require interior support, providing wide-open, clear-span building interiors—ideally suited for manufacturing and warehouses.
• Durability and longevity: Steel is resistant to many common problems other materials face, such as decay and warping.
• Design flexibility and aesthetics: Steel can be formed into complex and detailed shapes, allowing for unique architectural designs.
• Speed of construction: Prefabricated steel components are made off-site, which reduces on-site construction time.
• Fire resistance: While steel is not fireproof, it can be coated with fire-resistant materials to improve its performance in a fire.
• Sustainability and recyclability: Steel is 100% recyclable, reducing its environmental impact and making it a green building option.

Limitations of Weld-Up structures

• Higher cost: Welding is labor intensive and increases construction costs compared to bolted connections.
• Skilled Labor: Welded structures require specialized labor, and depending on the project location, the availability of skilled welders may be limited.
• Complexity: Complex weld patterns can slow construction and increase the chances of deformation in the components.
• Site Conditions: Welding may not be allowed in certain areas due to safety concerns, environmental regulations, or weather conditions.

Innovations

Recent advances in material science and technology have brought about developments in the design and manufacturing of metal components.

• High-performance steels: New steel alloys are being developed that are even stronger, more durable, and more corrosion-resistant, reducing maintenance costs over time.
• Automation in fabrication: Robotics and automated fabrication are speeding up the production of steel components and improving precision in steel cutting, welding, and assembly.
• Sustainable practices: Innovations like green steel – produced using lower carbon methods – is making steel production more environmentally friendly.

Future

Future trends will see more innovative technology in steel construction, such as sensors in steel frames that monitor the structural health of buildings in real time. This will change building maintenance and safety inspections.

Structural-steel buildings are often confused with Pre-Engineered Metal Buildings (PEMBs). They’re different, and the two building methods are considered alternatives. Here are their key differences:

Design approach. Weld-up metal building kits are custom-designed and engineered for each project, allowing infinite design possibilities. In contrast, PEMB metal building kits are more standardized and offer design limitations.

Fabrication and assembly methods. Weld-up metal buildings are built on-site by cutting and welding steel components, while the components of a PEMB kit are manufactured at the factory and then bolted together at the job site.

Cost. Weld-up metal buildings cost between $20 and $45 per square foot, while PEMBs cost between $10 and $25 per square foot, making them more suitable for smaller projects.

For additional cost details, see our metal building prices page.

Applications and end uses. PEMB systems are for smaller structures like warehouses and garages, while weld-up buildings are best suited for large, complex projects like skyscrapers, bridges, and stadiums.

Advantages and disadvantages

• Weld-up metal building Pros: Custom design, high strength, durability, flexibility.
• Weld-up metal building Cons: Higher upfront cost, longer construction time.
• PEMB Pros: Lower cost, faster construction, suitable for smaller projects.
• PEMB Cons: Limited customization, shorter lifespan.

Overall, the ideal building method will depend on what you intend to use the structure for and how complex it is. Structural may be better if the building is free-form or has multiple stories, as PEMBs can only have a maximum height of 30 feet (roughly two stories).

For more, see our article on the advantages of pre-engineered steel buildings.

In summary

Structural steel offers strength, durability, adaptability, and sustainability benefits. It’s a good option for many projects, from high-rise commercial skyscrapers to industrial warehouses to infrastructure projects. As the construction industry advances, structural steel will remain a part of current construction methods.