What is Steel Rebar? How to Calculate Steel Rebar For Building?

What are Steel Rebars?

A type of steel reinforcement used frequently in reinforced concrete and masonry structures is steel rebar, also known as reinforcing steel or reinforcement steel. To strengthen the bond between the steel and the concrete, it is made of carbon steel and has a surface that is ridged or ribbed.

Rebar made of steel is used to give concrete structures more durability and strength. It helps the structure resist cracking and collapse under tension by absorbing tensile and compressive forces. The choice of steel rebar will depend on the structure’s design and specifications as it comes in a variety of sizes and grades.

Rebar made of steel is produced by hot rolling and typically comes in diameters ranging from 6mm to 50mm. It is also produced in a variety of lengths, most frequently 6 meters, 9 meters, and 12 meters. To ensure compliance with regional building codes and standards, steel rebar is frequently marked with information about its size, grade, and manufacturer.


Tensile Strength 

The maximum stress a material can withstand before cracking or breaking under tension is known as tensile strength. In other words, it refers to a material’s capacity to withstand being torn apart by opposing forces. Megapascals or pounds per square inch (psi) are units of force per unit area that are used to measure it (MPa).

The tensile strength of a material is a crucial characteristic, especially if it will be used in applications where it will be stretched or subjected to heavy tension. Tensile strength, for instance, is a crucial factor to take into account when choosing materials for the construction of buildings, bridges, and other load-bearing structures in structural engineering.

A material’s composition, microstructure, and processing techniques all have an impact on its tensile strength. External elements like temperature, humidity, and exposure to corrosive substances can also have an impact on it. Generally speaking, materials with higher tensile strengths are stronger and more resilient than those with lower tensile strengths.


Compressive Strength

The maximum compressive stress or load that a material can withstand before failing or disintegrating is known as compressive strength. It is a material’s capacity to withstand being squeezed or crushed by a load. Common units of force per unit area used to measure compressive strength include pounds per square inch (psi) and megapascals (MPa).

Materials that will be subjected to compression or crushing loads, like concrete walls and columns, must have a certain amount of compressive strength. The compressive strength of a material is a crucial factor in structural engineering when choosing materials for building construction, bridge construction, and other load-bearing structures.

The composition, microstructure, and processing techniques of a material all have an impact on its compressive strength. A material’s compressive strength may also be impacted by environmental variables like temperature, humidity, and contact with corrosive substances.

Compression testing is a common method for determining a material’s compressive strength. In this procedure, a sample of the material is put under a load that gradually increases until it fails or fractures. The sample’s compressive strength is then calculated by dividing the maximum load it could withstand by the sample’s cross-sectional area.


How to Calculate Steel Rebar for Building?

The quantity of steel required for the reinforcement of concrete structures must be determined in order to calculate steel rebar for building construction. The steps are as follows:

Ascertain the concrete structure’s dimensions: The concrete building’s length, width, and height should all be measured. To determine the volume of the concrete, multiply these dimensions.

Establish the necessary rebar spacing: The rebar spacing is determined by the structure’s design and the local building codes. For information on the necessary rebar spacing, refer to the building plans or specifications.

Determine the total length of the necessary rebar: Divide the total number of bars needed for the structure by the sum of each bar’s length.

Determine the weight of the necessary rebar: Add the weight per unit length of the rebar to the total length of the rebar. The manufacturer will typically provide the rebar’s weight per unit length.

Include an additional amount to account for waste and overlaps: It is advised to include an additional 5% to 10% of the total weight of steel rebar needed.


Steel rebar ties

Reinforcing steel bars (rebar) are held together in a reinforced concrete structure by steel rebar ties, which are wire ties. These ties, which hold the rebar in place before the concrete is poured, are typically made of annealed wire.


To form a solid connection, rebar ties are typically twisted or bent around the rebar intersection. In order to strengthen concrete structures like buildings, bridges, and roads, they are frequently used in construction. Rebar ties are used to help make sure that the rebar is evenly spaced and aligned, which enhances the structure’s overall strength and durability.

It is essential to keep in mind that building codes and regulations, which vary by location, apply to the use of rebar ties. Therefore, before using rebar ties in any construction project, it is crucial to speak with a licensed engineer or building code official.


Steel rebars Stirrup

In reinforced concrete structures, steel rebar stirrups also referred to as rebar stirrups, are a type of reinforcement that adds strength and stability. The longitudinal bars (also known as main bars) in the concrete are surrounded by these reinforcements, which are typically formed into a loop or U shape from steel rebar.


Rebar stirrups are used to help resist lateral forces that might otherwise cause cracks or other failures in the concrete. Additionally, they aid in maintaining the longitudinal bars’ spacing, ensuring that they stay in the proper location throughout the concrete’s pouring and curing processes.

Rebar stirrups can either be prefabricated off-site and delivered to the construction site ready for installation, or they can be formed on-site using specialized bending tools. They are frequently utilized in a range of reinforced concrete structures, such as walls, columns, and beams.


The use of rebar stirrups is governed by building codes and regulations, just like the use of all other types of reinforcement in concrete structures. Before utilizing rebar stirrups in any construction project, it is crucial to seek advice from a licensed engineer or building code official.




Here is an illustration of how to figure out how much steel rebar is needed for a concrete structure:

Let’s say we need to use rebar with a 150mm spacing and we have a concrete column that is 1 meter by 1 meter by 3 meters.

The column’s volume is equal to 1 m by 1 m by 3 m or 3 cubic meters.

Rebar spacing is 150mm, or 0.15 meters.

The total length of rebar needed is calculated as follows: column perimeter times number of bars = (2 x 0.15 m), (2 x 0.15 m), and (3 x 0.15 m) times 4 bars = 3.6 m x 4 = 14.4 m.

The required weight of the rebar is calculated as follows: 14.4 meters times 0.89 kilograms per meter (assuming a rebar with a diameter of 12 millimeters), which equals 12.7 kilograms.

Subtract an additional amount to account for waste and overlaps (12.7 kg + 10% = 13.97 kg).

Hence the total rebar required for 3 cubic meters is 13.97 kg nearly equal to 14 kg.

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