Concrete has quite high compressive strength, but low tensile strength. However, steel has very high tensile strength. That is why we insert steel reinforcements in the tension zones of a structure.
Now, you can provide reinforcements in concrete beams in two ways - single reinforcement (commonly used) and double reinforcement. Today, we will talk about doubly reinforced beams.
In case of doubly reinforced beams, steel reinforcements are inserted into both the tensile and compression zones of a beam. Meaning, at the top and the bottom of the beam. In contrast, the singly reinforced beams have reinforcements only at the bottom, where it needs tensile support.
Further, in singly reinforced beams, there are two steel bars to be provided, but you need not consider the moment of resistance. However, when you do need to consider this, you have to provide additional bars to reduce the tension in the over-reinforced section.
In case of doubly reinforced beams, though, the matter is quite different. In this case you will have to find out the moment of resistance first! Then, you need the area of tension steel (Ast) and area of compression steel (Asc). Combined, they would overcome the Excess Bending Moment (Mu2).
Designing doubly reinforced beams
When we begin designing a doubly reinforced beam, we need to be careful about some factors. For example, the depth of the beam may need to be limited to given values, be it for architectural reasons or otherwise.
If that is the case, you will have to implement the doubly reinforced beam with the requirement to resist more than standard limiting moment in that confined space you have for it. As a general rule of thumb, we design doubly reinforced beams when the go-to design moment of resistance is higher than that of the limiting moment of resistance.
The beam can be defined as a structural member that carries all vertical loads and resists bending. There are several types of materials used for beams, such as steel, wood, fibers, etc. But the most common material is reinforced concrete.
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Published By
Rajib Dey
www.constructioncost.co
~~~~~~~~~~~~~~~~~~~~~~~~~~
Now, you can provide reinforcements in concrete beams in two ways - single reinforcement (commonly used) and double reinforcement. Today, we will talk about doubly reinforced beams.
In case of doubly reinforced beams, steel reinforcements are inserted into both the tensile and compression zones of a beam. Meaning, at the top and the bottom of the beam. In contrast, the singly reinforced beams have reinforcements only at the bottom, where it needs tensile support.
Further, in singly reinforced beams, there are two steel bars to be provided, but you need not consider the moment of resistance. However, when you do need to consider this, you have to provide additional bars to reduce the tension in the over-reinforced section.
In case of doubly reinforced beams, though, the matter is quite different. In this case you will have to find out the moment of resistance first! Then, you need the area of tension steel (Ast) and area of compression steel (Asc). Combined, they would overcome the Excess Bending Moment (Mu2).
Designing doubly reinforced beams
When we begin designing a doubly reinforced beam, we need to be careful about some factors. For example, the depth of the beam may need to be limited to given values, be it for architectural reasons or otherwise.
If that is the case, you will have to implement the doubly reinforced beam with the requirement to resist more than standard limiting moment in that confined space you have for it. As a general rule of thumb, we design doubly reinforced beams when the go-to design moment of resistance is higher than that of the limiting moment of resistance.
The beam can be defined as a structural member that carries all vertical loads and resists bending. There are several types of materials used for beams, such as steel, wood, fibers, etc. But the most common material is reinforced concrete.
~~~~~~~~~~~~~~~~~~~~~~~~~~
Published By
Rajib Dey
www.constructioncost.co
~~~~~~~~~~~~~~~~~~~~~~~~~~
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