For 45 degree 4* dia
90 degree 8* dia
180 degree 16* dia for anchorage value
so anchorage value at 45 degree= 4*12=48 mm

Anchorage value for 12 mm diameter steel bar at 45 degree bent

Introduction
In civil engineering, anchorage refers to the ability of a reinforcement bar (rebar) to resist pull-out forces. The anchorage value is a measure of this resistance, and it is determined based on various factors such as the diameter of the bar, the angle of bending, and the type of concrete used. In this case, we will determine the anchorage value for a 12 mm diameter steel bar at a 45-degree bend.

Calculation Method
To calculate the anchorage value for a 12 mm diameter steel bar at a 45-degree bend, we need to consider the following steps:

1. Determine the bond stress: The bond stress is the stress developed between the steel reinforcement and the surrounding concrete. It can be calculated using the formula:

Bond stress = (2 x τbd x sinθ) / (π x φ)

Where:
- τbd is the bond stress development length
- θ is the angle of bending (45 degrees in this case)
- φ is the diameter of the steel bar (12 mm)

2. Determine the bond stress development length: The bond stress development length is the length along which the bond stress is fully developed. It can be calculated using the formula:

Bond stress development length = (3.5 x τbd x φ) / σst

Where:
- τbd is the bond stress development length
- φ is the diameter of the steel bar (12 mm)
- σst is the permissible bond stress

3. Determine the permissible bond stress: The permissible bond stress is the maximum allowable bond stress for a given concrete grade. It can be obtained from relevant design codes or specifications. Let's assume a permissible bond stress of 0.8 MPa for this calculation.

4. Calculate the bond stress development length: Using the formula mentioned in step 2, substitute the values of τbd, φ, and σst to calculate the bond stress development length.

5. Calculate the bond stress: Using the formula mentioned in step 1, substitute the values of τbd, θ, and φ to calculate the bond stress.

Conclusion
In conclusion, the anchorage value for a 12 mm diameter steel bar at a 45-degree bend can be determined by calculating the bond stress and the bond stress development length. The bond stress is influenced by factors such as the angle of bending, the diameter of the bar, and the type of concrete used. By following the calculation method outlined above, the specific anchorage value for this particular case can be determined. It is important to note that the values used in this calculation are subject to change based on design codes, specifications, and project requirements.