# Stress-strain relationship for reinforcement and prestressed reinforcement

The relationship between stress-strain for concrete is described in the figure below. Characteristics vary by the value of εs and are classified by the intervals shown. Figure 1

This diagram illustrates compression (left-hand side) and tension (right-hand side).

• For any εs less than or equal to the strain (εsuc,θ), the stress (σsds)) for compression equals 0.
• With εsuc,θ ≤ εs ≤ εstc,θ (interval IV of the working curve of compression), the stress becomes • With εstc,θ ≤ εεs ≤ -0.02 (interval III of the working curve of compression), the stress becomes σsds) = f2.0cds)
• With -0.02 ≤ εs ≤ εspcs) (interval II of the working curve of compression), the stress is calculated as • With εspcs) ≤ εs ≤ εsps) (interval I of the working curve of both compression and tension), the stress becomes σsds) = εs Espds)

• With εspcs) ≤ εs ≤ 0.02 (interval II of the working curve of tension), the stress is calculated as • With 0.02 ≤ εs ≤  εst,θ (interval III of the working curve of tension), the stress becomes σsds) = f2.0ds)

• With εsu,θ ≤ εs ≤ εst,θ (interval IV of the working curve of tension), the stress becomes • With εs > εsu,θ the stress becomes σsds) = 0 for tension.

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