Overhanging beams are an important part of modern buildings, especially for structures that need extra support outside of the main building’s perimeter. These beams are made to stand up to different kinds of forces and loads, which makes them versatile and reliable building parts. In this guide, we’ll take an in-depth look at overhanging beams and talk about their types, properties, uses, benefits, and drawbacks.
What is a beam?
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A beam is a vital part of any structure, used to hold up anything from the roof to the deck of a bridge or other large object. Bending moments, shear forces, and lateral forces all bend beams, but beams are supposed to resist all of them. When a beam is subjected to a load, the result is a longitudinal stress. This load is taken off the beam by its resistance to bending, which makes it an important part of any structural system.
The most common kinds of beams are simply supported, cantilever, fixed, continuous, and overhanging beams. Beams can be made out of many different things, like wood, steel, or concrete.
Overhanging beams: What are they?
Overhanging beams are special construction beams in which one end hangs over rather than rests on a support. The design has elements of both cantilever and simply supported beams. Balcony or shade structures often make use of overhanging beams, since the additional length of the beam allows for more seating or standing room.
The beam’s length beyond the support is an important factor to think about while dealing with overhanging beams. The typical amount of overhang is 1 metre (3 feet, 3 inches); therefore, that’s what you should aim for. This is because deflection, bending, and shear stress make it more likely that a structure will fail in an extended part that isn’t supported and wasn’t designed well.
Overhanging beams: Types
There are two types of overhanging beams based on the number of ends that extend beyond the support:
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Single overhanging beam
A single overhanging beam is a type of beam in which one end of the beam extends beyond the support. This type of beam is a combination of simply supported and cantilever beams. An example of a single overhanging beam is a balcony that extends from the framed structure on one side. When a load is put on the part of the beam that is hanging, the weight is safely transferred to the part of the beam that is holding it up. To make sure that a single overhanging beam can safely hold the weight and load it is meant to carry, designers must take into account a number of factors, such as the size and shape of the beam, how it is supported, and how much weight is put on the part that is hanging.
Double overhanging beam
A double overhanging beam refers to the type of beam in which both ends of the beam extend beyond the support. An example of a double overhanging beam is a balcony that extends from the framed structure on both the front and back or left and right sides. When a load is put on the hanging parts of the beam, the weight is safely transferred to the support (a hinge or roller) using an equivalent bending moment. When making a double overhanging beam, the size and shape of the beam, the type of support used, and the load on the hanging parts must all be carefully thought out. This is to make sure that the beam can safely hold the weight and load it is meant to carry.
Overhanging beams: Properties
To ensure its structural integrity and safety, an overhanging beam must possess certain properties. These properties include:
Sufficient strength to bear the loads acting on it
The overhanging beam must be built and designed so that it can hold the weight that is expected to be put on it. This includes the weight of any structures or objects that are attached to it, as well as any environmental loads such as wind or snow.
Resistance to chemical and physical weathering agencies
Overhanging beams are often exposed to various weathering agents, such as moisture, heat, and chemicals. Because of this, the materials used to build it must stand up to these things without breaking down.
Durability and soundness
Overhanging beams should be durable and sound over their expected lifespan. This includes making sure that the materials used to build it are not likely to rot, decay, or break down in other ways.
Width to depth ratio
The ratio of a beam’s width to its depth should be more than 0.3 for it to be structurally stable and not bend too much.
Minimum width
A beam that hangs over something else should be at least 200 mm wide to make sure it can hold the weight it’s supposed to.
Depth of overhanging
To ensure that the beam is able to withstand the stresses of bending and shearing, the depth of the section that hangs over shouldn’t be any more than one-fourth of the clear span.
Overhanging beams: Uses
One of the main uses of an overhanging beam is in the construction of balconies or overhanging structures. In such cases, the beam extends beyond the exterior wall of the building to provide support for the balcony or other structure. Overhanging beams can also be used in other situations where extra support is needed beyond the edge of a building or structure.
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Overhanging beams: Advantages
Reduces uniaxial moment in the column
The use of overhanging beams can help reduce the uniaxial moment in the column, which can improve the structural stability of the building.
Decreases one-sided load in a beam
Overhanging beams can help to reduce the one-sided load in a beam, which can help to improve the overall balance and stability of the structure.
Low sagging
Overhanging beams are made so that they don’t sag, which makes them stronger and last longer.
Overhanging beams: Disadvantages
Restriction in the extension length
The length of an overhanging beam is limited by how far it can go past the support. This can restrict their use in certain applications..
Hard to construct
Most of the time, overhanging beams are harder to build than regular beams because they need more support and reinforcement to keep their structure strong. This can add to the cost and complexity of construction.
FAQs
What is an overhanging beam?
An overhanging beam goes past its support and is used to hold up balconies or other structures that hang over the ground.
What are the types of overhanging beams?
The two main types of overhanging beams are single and double overhanging beams.
What are the advantages of using overhanging beams?
Advantages include reducing the uniaxial moment in the column, decreasing the one-sided load in a beam, and having low sagging.
What are the properties of overhanging beams?
Properties include sufficient strength, resistance to weathering, durability, a width-to-depth ratio of over 0.3, and a minimum width of 200mm.
What are the disadvantages of using overhanging beams?
Disadvantages include length restrictions and difficulty in construction compared to normal beams.
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