Loss of stress due to relaxation of steel is influenced by:

Relaxation of steel refers to the phenomenon where steel gradually loses its stress over time under constant strain. Several factors can contribute to the loss of stress due to relaxation of steel, but the most significant factor is the initial stress in the steel itself.

1. Initial stress in steel:
The initial stress in the steel is the primary factor that influences the loss of stress due to relaxation. When steel is subjected to an initial stress, it tends to relax and reduce its stress level over time. This relaxation is a result of the redistribution of internal forces within the steel structure, which leads to a decrease in the overall stress.

The initial stress in the steel can be caused by various factors such as applied loads, temperature changes, or manufacturing processes. The higher the initial stress in the steel, the greater the relaxation and subsequent loss of stress over time.

2. Elastic deformation of concrete:
While elastic deformation of concrete can affect the overall behavior of a reinforced concrete structure, it has a minimal influence on the loss of stress due to relaxation of steel. Elastic deformation refers to the temporary deformation of concrete under applied loads, which returns to its original shape once the load is removed. This deformation does not significantly contribute to the relaxation of steel stress.

3. Anchorage slip:
Anchorage slip refers to the movement or displacement of the steel reinforcement within the concrete. It can occur due to inadequate bond between the reinforcement and the surrounding concrete, leading to a loss of stress in the steel. However, anchorage slip is not a significant factor influencing the relaxation of steel stress compared to the initial stress in the steel.

4. Friction:
Friction between the steel reinforcement and the surrounding concrete can affect the transfer of stress between the two materials. If there is a high level of friction, the stress transfer may be more efficient, resulting in a lower loss of stress due to relaxation. However, the influence of friction on the relaxation of steel stress is secondary to the initial stress in the steel.

In conclusion, while factors such as elastic deformation of concrete, anchorage slip, and friction can have some influence on the loss of stress due to relaxation of steel, the most significant factor is the initial stress in the steel itself. The higher the initial stress, the greater the relaxation and subsequent loss of stress over time.