Bent up bars, also known as stirrups, are commonly used in reinforced concrete structures to provide lateral support and increase the strength of beams and columns. When constructing these structures, it is crucial to accurately calculate the cutting length of the bent up bars to ensure the structural integrity and safety of the building. In this article, we will delve into the importance of calculating the cutting length of bent up bars, the factors that affect it, and the step-by-step process to determine it accurately. This information will be beneficial for both construction professionals and individuals looking to understand the fundamentals of reinforced concrete structures.

## How to calculate cutting length of bent up Bar(crank bar)

Cutting length of bent up bars or crank bars is a crucial step in the reinforcement process of any concrete structure. These bars are bent or curved at specific angles to provide structural stability and resistance against external forces such as wind, earthquakes, and heavy loads. The accurate calculation of the cutting length for these bent up bars is essential for ensuring the strength and durability of the concrete structure.

Here are the steps involved in calculating the cutting length of bent up bars:

Step 1: Determine the Curving Angle

The first step is to determine the angle at which the bar is bent or curved. This angle is also known as the crank angle or the bend angle. In most cases, the crank angle is usually 45, 60, or 90 degrees. The crank angle is essential in determining the length of the bent up bar.

Step 2: Calculate the Bend Length

The bend length is the actual distance from one end of the bar to the point where the bar starts to bend or curve. This length is critical in finding the total length of the bent up bar. The bend length is calculated by dividing the bend angle in degrees by 90, and then multiplying by the length of the bar.

Bend Length = (Bend Angle / 90) x Bar Length

Step 3: Find the Length of Inclined Portion

The inclined portion of a bent up bar is the length of the bar that extends beyond the point of bending. This portion is perpendicular to the bend length. The length of the inclined portion can be calculated using basic trigonometric functions, specifically the sine and cosine functions.

Inclined portion length = Bend Length x sine (90 – Bend Angle)

Step 4: Calculate Cutting Length

The cutting length of the bent up bar can now be calculated by adding the bend length and the inclined portion length together.

Cutting Length = Bend Length + Inclined portion length

It is important to note that the crank bar is cut at a right angle, and the inclined portion is not included in the cutting length. Therefore, to find the cutting length of the crank bar, the inclined portion length needs to be deducted from the calculated length.

Cutting Length of Bent Up Bar = Total length – Inclined portion length

Step 5: Consider Overlap Length

In some cases, where reinforcement bars are required to overlap, the cutting length of the bent up bars needs to be adjusted. The overlap length is usually specified in the structural drawings and needs to be added to the calculated cutting length of the bent up bar.

In conclusion, the accurate calculation of the cutting length of bent up bars is essential in the successful reinforcement of concrete structures. Civil engineers and construction experts must follow the above steps to ensure that the bent up bars are cut to the correct length, providing the required strength and stability to the structure. Any miscalculation in the cutting length can result in structural failure and compromise the safety of the building. Therefore, it is crucial to follow these steps carefully and accurately.

## what is cutting length?

Cutting length is a term commonly used in civil engineering, particularly in reinforced concrete structures. It refers to the length of the steel bar that is required to be cut for use in a reinforced concrete structure. This length is determined by the structural requirements of the design and is an essential aspect in the construction process.

In reinforced concrete structures, steel bars are used to provide tensile strength to the concrete, which is otherwise weak in tension. These steel bars, also known as reinforcing bars or rebars, are typically placed in a grid pattern within the concrete elements. The placement of these bars is crucial to the structural integrity and strength of the concrete element.

Before the construction process begins, civil engineers need to carefully analyze the structural drawings and calculate the cutting length of each steel bar. This calculation is done based on the structural design and the dimensions of the concrete element in which the bar will be placed. The cutting length is measured from the end of the bar, where the load is to be applied, to the end where the bar will be bent or terminated.

The cutting process of steel bars is usually done at the construction site using a power saw or steel scissors. The cutting length needs to be accurate to avoid wastage of steel, which can significantly increase construction costs. It is essential to adhere to the specified cutting length to ensure the structural integrity of the concrete element. Any errors or deviations can compromise the strength of the structure and affect its overall stability.

In addition to the cutting length, there are also other factors that need to be considered when cutting steel bars, such as lap length and bend length. Lap length refers to the length of the overlapping section of two adjacent bars, while bend length refers to the minimum distance between the end of the steel bar and the axis of the bend. These factors are crucial in preventing failure points and ensuring the structural stability of the concrete element.

In conclusion, cutting length is a critical aspect of reinforced concrete construction. Civil engineers must accurately calculate the cutting length of steel bars to ensure the strength and structural integrity of concrete elements. Any errors in cutting length can compromise the structural stability of the element and even the safety of the structure itself. Therefore, it is essential to follow the specified cutting length as per the structural design to ensure a successful and robust construction.

## how to calculate cutting length of bent up Bar (crank bar)

The cutting length of a bent up bar, also known as a crank bar, is calculated depending on the degree of the bend and the position of the bar within the structure. Bent up bars are commonly used in reinforced concrete structures to resist shear forces, distribute stress, and reinforce corners and junctions. Proper calculation and fabrication of bent up bars is crucial to ensure the structural integrity and strength of the overall structure.

To start, it is important to determine the degree of the bend needed for the crank bar. This can be determined by referencing the structural drawings for the specific project. The degree of the bend is usually given in terms of an angle, such as 45 degrees or 90 degrees. Once the degree of the bend has been determined, the next step is to carefully mark this angle on the bar.

Next, measure the length of the straight portion of the bar. This is the length of the bar that will remain straight and will not be bent. This is also known as the ‘effective length’ of the bar. Add the length of the straight portion to the desired degree of the bend in order to find the total length of the bar. For example, if the straight length is 1.5 meters and the desired degree of bend is 90 degrees, the total length of the bar will be 1.5+0.5 = 2 meters.

Once the total length of the bar has been determined, the next step is to calculate the length of the arc formed by the bend. This arc length will vary depending on the degree of the bend. For a 90-degree bend, the arc length is equal to the diameter of the bend or ½ the circumference of the bend. The diameter of the bend can be determined by multiplying the diameter of the bar by 2. For example, if a 12mm diameter bar is used, the diameter of the bend will be 24mm. Therefore, the arc length will be ½ x π x 24 = 37.7mm.

After finding the arc length, add this to the total length of the bar to obtain the cutting length. In our example, the cutting length will be 2m + 0.0377m = 2.0377m. It is always recommended to round off the cutting length to the nearest millimeter for fabrication purposes.

In situations where the bent up bar is located at a corner of the structure and the final length needs to be determined once the bar is fixed in its position, the following formula can be used:

Cutting Length = √(L1^2 + L2^2)

Where L1 is the length of the straight portion of the bar and L2 is the arc length.

In conclusion, the calculation of cutting length for a bent up bar involves determining the degree of the bend, measuring the straight length of the bar, adding the length of the arc to the total length, and rounding off to the nearest millimeter. Accurate calculation and proper fabrication of bent up bars are essential for the overall stability and strength of reinforced concrete structures.

## Conclusion

In conclusion, accurate calculation of the cutting length of bent-up bars is crucial in ensuring the structural stability and strength of reinforced concrete structures. By following the steps outlined in this article, engineers and builders can accurately determine the required length of bent-up bars, reducing the risk of errors and potential structural failures. It is essential to pay attention to the bending angle and the number of bends when calculating the cutting length, as well as considering any critical factors such as stress distribution and bar end anchorage. With precise calculations, bent-up bars can be efficiently utilized to reinforce concrete structures, providing durability and longevity. Therefore, it is essential to understand and master the process of calculating the cutting length of bent-up bars to ensure the safety and reliability of buildings and structures