Structural steel framing systems play a critical role in the construction of modern buildings. Steel frames provide the skeletal structure that supports the loads of the building, ensuring safety and stability. These frames are composed of a combination of beams, columns, and other structural elements designed to bear the weight of the building’s floors, walls, and roof. In this article, we will explore three main types of structural steel framing systems: Skeleton Steel Framing, Wall Bearing Steel Framing, and Long Span Steel Framing. We will discuss their configurations, applications, and advantages, helping you understand when and how each system is applied in construction projects.
Overview of Structural Steel Framing Systems
A structural steel frame is a framework made of steel columns, beams, and other steel components that support a building’s loads. Steel framing is integral to modern architecture, providing both flexibility and strength for a variety of building types. There are several types of structural steel framing systems, each with unique configurations and suitable applications. The three primary types are:
- Skeleton Steel Framing
- Wall Bearing Steel Framing
- Long Span Steel Framing
Each system has distinct characteristics that make it suitable for different building needs, ranging from low-rise homes to large industrial structures.
Skeleton Steel Framing System
The Skeleton Steel Framing System is one of the most common and widely used structural framing systems. In this system, the building is supported by a series of steel beams and columns arranged in a grid pattern. These steel components are connected through various types of steel connections to form a rigid, stable structure.
Description and Configuration
Skeleton steel framing is made up of steel beams and columns, with the beams forming the horizontal elements and the columns providing vertical support. The perimeter of the structure is typically framed with spandrel beams that support the weight of exterior masonry walls. These steel frames are designed to distribute the loads evenly across the structure. As shown in the plan view and constructed steel framing images, the columns and beams form the skeletal structure of the building, providing the essential framework for the construction.
Applications
One of the main advantages of skeleton framing is its flexibility in terms of floor plan design. The distance between columns can be adjusted to meet the functional and aesthetic requirements of the building. Additionally, skeleton framing systems allow for the construction of multi-storey structures, as the steel beams and columns bear the load of the floors above.
Steel Connections
In a skeleton frame structure, steel beams are connected to the columns through various types of connections, including bolt and welded connections. Bolted connections, such as flexible end plates, fin plates, and double angle cleats, are commonly used to join the beams and columns. These connections allow for easy assembly and disassembly, making them ideal for structures that may need to be modified or expanded in the future.
Advantages
Skeleton steel framing systems offer several benefits, including:
- Design Flexibility: There are no restrictions on the floor or roof areas, which allows for larger and more open spaces.
- Structural Strength: The system can support a variety of load types and is suitable for multi-storey buildings.
- Efficiency: The frame allows for rapid construction with minimal material waste.
Wall Bearing Steel Framing System
The Wall Bearing Steel Framing System uses the walls of the building, both exterior and interior, to support structural loads. These walls carry the end of steel beams, which in turn support the weight of the floors and roof. This system is generally used in low-rise construction, where the load requirements are less demanding.
Description and Configuration
In a wall bearing system, steel beams are placed at the top of the walls to carry the loads from the floor and roof. The walls, whether made of masonry or reinforced concrete, serve as the primary support for the beams. The weight from the structure is transferred to the walls, which must be strong enough to handle both vertical and horizontal loads. This type of framing system is often used in single-storey homes or small buildings.
Applications
A typical application of the wall bearing framing system is in single-story homes where steel beams are used to support floor loads, with the ends of the beams resting on foundation walls. Additionally, wall bearing framing is used in applications like lintels, where steel beams are placed over openings in walls (such as doors and windows) to provide support.
Challenges
The main limitation of the wall bearing system arises when used in multi-storey buildings. To support the additional load, the size of the bearing walls must be significantly increased. This can lead to larger and more cumbersome structures. One way to address this challenge is by using reinforced concrete walls, which provide greater strength and stability.
Advantages
- Cost-Effective: Suitable for low-rise buildings, this system is often more affordable than other framing systems.
- Simpler Design: The use of existing walls for support reduces the need for extensive steel columns.
- Foundation Strength: This system transfers loads directly to the foundation, reducing the need for complex load distribution systems.
Long Span Steel Framing System
The Long Span Steel Framing System is used when large, unobstructed areas are required, such as in warehouses, auditoriums, and sports arenas. These systems are designed to span long distances without the need for many intermediate supports, allowing for more open and flexible space.
Description and Configuration
Long span steel framing systems include several types of structural elements designed to span wide areas. These elements include:
- Girders: These are large horizontal beams used to support other structural members. They are typically employed when the depth of the member is restricted, and they carry loads across large open areas.
- Trusses: Trusses are triangular frameworks that can span long distances without requiring deep beams. They are known for their ability to control deflection and maintain stiffness.
- Arches: Arches are curved structural elements that can carry heavy loads over long distances. They are typically used in roofs and bridges.
- Rigid Frames: These frames consist of steel columns and beams that are rigidly connected to create a stable frame structure. They are often used in large open spaces like gyms or auditoriums.
Applications
Long span systems are ideal for large buildings where unobstructed space is necessary. For example, girders can be used in lower storeys where a large clear space is required. Trusses are commonly used for larger spans where depth limitations are not an issue. Arches and rigid frames are often employed in buildings like sports arenas, churches, and shopping malls.
Advantages
- Unobstructed Space: Long span systems allow for wide, open areas without columns interrupting the space.
- Aesthetic Flexibility: Systems like rigid frames and arches offer attractive architectural possibilities, making them suitable for iconic or visually striking buildings.
- Structural Efficiency: Long span systems are designed to handle large loads while maintaining structural integrity.
Conclusion
Each type of structural steel framing system offers unique advantages that make it suitable for different types of buildings and construction requirements. Skeleton steel framing is ideal for large, multi-storey structures due to its flexibility and ability to support large loads. Wall bearing steel framing works best for low-rise buildings, relying on walls to support the structure. Lastly, long span steel framing systems are designed for large, open spaces, providing flexibility in design and layout. Understanding the different steel framing systems and their applications is essential for architects, engineers, and builders in creating safe, efficient, and aesthetically pleasing buildings.