Infill framing refers to masonry, such as brick or concrete blocks, used to fill the spaces within a structural frame, typically made of steel or reinforced concrete. This bounding frame consists of columns and beams (or slabs) that surround and support the masonry infill.
In essence, infill framing is a non-structural wall system that relies on the surrounding frame for its stability and load-bearing capacity. It's important to understand its role and limitations in building construction.
Key Aspects of Infill Framing:
- Non-Structural Nature: Infill walls are primarily for enclosure and separation, not for bearing the weight of the building above. The structural frame carries the loads.
- Materials: Common infill materials include brick, concrete masonry units (CMU), and lightweight blocks.
- Bounding Frame: The structural frame, usually steel or reinforced concrete, provides support and resistance to lateral loads (like wind or earthquakes).
- Purpose: Infill walls serve several purposes:
- Creating Enclosed Spaces: Defining rooms and areas within a building.
- Providing Thermal Insulation: Depending on the infill material, it can contribute to energy efficiency.
- Offering Fire Resistance: Masonry infill can improve the fire rating of a building.
- Enhancing Acoustic Performance: Helping to reduce noise transmission between spaces.
- Considerations:
- Seismic Performance: The interaction between infill walls and the frame can be complex during earthquakes. Infill walls can increase stiffness and potentially alter the building's dynamic response.
- Thermal Expansion: Differences in thermal expansion between the infill and the frame can cause cracking.
- Differential Settlement: If the foundation settles unevenly, the infill walls can crack.
- Example: Think of a steel-framed warehouse. The steel columns and beams form the primary structure, while concrete blocks are used to fill in the spaces between the steel members to create the exterior walls.
Infill framing is a common construction technique that offers a balance between structural support from the frame and the functional benefits of masonry walls. However, careful consideration of its impact on the building's overall performance is crucial, especially in areas prone to seismic activity.
