What is a Framed Structure?

A frame structure is a structure built using beams, columns, and slabs to form a frame system to resist and transfer gravity and other lateral loads safely to the foundation. The gaps formed in the framed system are filled by constructing the walls. 

Framed Structures are commonly used in the construction of buildings, bridges, and other large structures.

This article outlines the basic features, types, pros, and cons of constructing framed construction for a project. 

The frame structure is used when the number of stories in a building is more and requires a large floor area free of walls. The features and elements of framed structure are explained in this article.

💡Note:
The opposite of framed construction would be mass construction, where walls and other elements are constructed as a single, solid unit instead of being assembled piece by piece. In mass construction, the weight of the structure is supported by the walls and other elements rather than by a frame. This approach to construction was common in ancient times and is still used in some parts of the world today, particularly for smaller structures such as houses and sheds. However, it is less common for larger or more complex buildings due to limitations in flexibility and the need for greater load-bearing capacity.

Read More On the Difference Between Framed and Load-Bearing Structure

Framed Structure

Load Transfer Mechanism

In a framed structure, the load transfer mechanism works through a combination of axial forces and bending moments.

When a load is applied to the structure, it creates a force that is transferred through the members of the frame. Each member of the frame is designed to resist a certain amount of force, and the overall load is distributed among the members based on their relative stiffness and strength.

The load is first transferred to the beams and columns, which are the primary load-bearing elements of the structure. The beams transfer the load to the columns, which then transfer the load to the foundation. The foundation then distributes the load to the soil, which is ultimately responsible for supporting the entire structure.

The load transfer mechanism in a framed structure also involves the development of bending moments. When a load is applied to a beam, it creates a bending moment that causes the beam to deform. This deformation results in a redistribution of the load among the members of the frame, which helps to ensure that the load is evenly distributed and the structure remains stable.

Features of Frame Structure

1. Frame structures are a planned arrangement of beams, columns, and slabs to resist large forces and moments that are developed due to heavy gravity and lateral loads.
2. Framed structures can be made out of reinforced cement concrete, steel or wood, etc.
3. They form a steel or concrete skeleton that collects the load and delivers them safely to the foundation.
4. The frame structural elements are connected either using pinned connections or fixed connections.
5. The space that is formed by the framed structural system is filled using wall construction. These walls can be either load-bearing or non-load-bearing walls. The load-bearing walls constructed in the framed structure are mainly shear walls.
6. Hence, the main structural or load-carrying elements of a framed structure are beams, columns, slabs, and shear walls (load-bearing walls).

Types of Framed Structure

1. Based on the material used for the framed structure:

• Steel Frame Structure
• R.C.C Frame Structures
• Wooden Frame Structures

2. Based on the connection between the elements of a frame structure:

• Rigid Frame System or Moment Frame System
• Fix Ended Rigid Frames
• Pin Ended Rigid Frames
•  Braced Frame System
• Portal Frames
• Gable Frames

Detailed explanations on the types are explained in the table below: 

A. Based on Material
1. Steel Frame Structure	Steel-framed structures employ a steel framework to support their weight, utilizing steel sections for columns, beams, and girders. Adequate bracing ensures resilience against wind and seismic forces, while lightweight and fireproof materials are commonly selected for both interior and exterior walls. Consequently, steel-framed structures resemble reinforced concrete structures (RCC), offering greater weight-bearing capacity and enabling larger column-free spaces compared to masonry counterparts.
2. R.C.C Frame Structure	RCC structures employ interconnected beams and girders to support floors, roofs, and walls, transferring loads to columns and foundations. Integration of all structural elements into a single piece ensures seamless continuity between columns, beams, and slabs, enhancing structural integrity. Continuous construction of RCC frames reduces deflections and bending moments, leading to cost-effective and safer building construction.
3. Wooden Frame Structure	Wood frame structures are widely utilized for their cost-effectiveness, comfort provision, and environmental sustainability. They offer economic advantages and thermal comfort, making them popular choices for various construction projects. Furthermore, their carbon-neutral nature and architectural flexibility contribute to sustainable building practices and design innovation.
B. Based on Connections
1. Rigid Frame Structure	The word rigid means the ability to resist deformation. Rigid frame structures can be defined as structures in which beams & columns are made monolithically and act collectively to resist the moments that are generated due to applied load. Rigid frame structures provide more stability. This type of frame structure resists the shear, moment, and torsion more effectively than any other type of frame structure. That's why this frame system is used in the world's most astonishing building Burj Al-Arab. It can be of two types: Pin-Ended Rigid Frame and Fixed-Ended Rigid Frame.
Pin-Ended Rigid Frame	A pinned-ended rigid frame system usually has pins as their support conditions. This frame system is considered to be non-rigid if its support conditions are removed.
Fixed-Ended Rigid Frame	In this type of rigid frame system end conditions are usually fixed.
2. Braced Frame Structure	In this frame system, bracing is usually provided between beams and columns to increase their resistance against the lateral forces and sideways forces due to applied load. Bracing is usually done by placing the diagonal members between the beams and columns. This frame system provides more efficient resistance against earthquake and wind forces. This frame system is more effective than a rigid frame system. Braced frame structures can be of two types: Gabled and Portal Frames
Gabled Frames	Gabled frame structures usually have a peak at their top. These frame systems are in use where there are possibilities of heavy rain and snow.
Portal Frames	Portal structural frames usually look like a door. This frame system is very much in use for the construction of industrial and commercial buildings

Advantages of Frame Structures

1. Framed construction possesses a simple geometry that can be rapidly constructed.
2. Its strength and stability are more compared to load-bearing structures
3. Multi-story or high-rise buildings are constructed using framed structural systems.
4. They are ideal for earthquake-resistant design
5. They are rigid and stated to withstand high deflection caused due to heavy gravity and lateral loads.
6. Floor space is used optimally.

Disadvantages of Frame Structures

1. The span length is restricted to 40 ft to avoid deflection due to bending and lateral deflections.
2. The cost of framed structure construction can be high, especially when compared to other types of construction methods such as brick or block construction.
3. Framed structures require regular maintenance to ensure that they remain in good condition. This can include painting, treating wood, and inspecting steel frames for corrosion.
4. Framed structures can be susceptible to fire due to the use of wood or other combustible materials. This can be mitigated with fire-resistant materials and proper fire safety measures, but it is still a concern.
5. Framed structures can transmit sound more easily than other types of construction, which can be a problem in multi-family or commercial buildings.
6. The materials used in framed structure construction, such as wood and steel, can have a significant environmental impact. Wood is a renewable resource, but steel production has a large carbon footprint.
7. Framed structures have certain design limitations due to the nature of their construction. For example, load-bearing walls must be placed at specific intervals, which can limit the flexibility of the floor plan.

Also Read: What is a Flexural Member?