Stress-Strain Relation in Hardened Concrete

Stress-Strain Relation in Hardened Concrete

1. Introduction to Hardened Concrete:

• Hardened concrete refers to concrete that has gained sufficient strength and stiffness after setting and curing.

2. Stress-Strain Relationship:

• It is a fundamental property that illustrates how hardened concrete deform under varying levels of stress.

3. Key Concepts:

• Elastic Behavior: Initially, concrete exhibits a linear, elastic response where stress and strain are proportional.
• Proportional Limit: The maximum stress at which the material still behaves elastically. Beyond this point, deformation is no longer proportional to stress.
• Ultimate Strength: The maximum stress that the concrete can withstand before failure.
• Post-Peak Behavior: After reaching ultimate strength, concrete experiences a reduction in stress with increasing strain until failure.

4. Important Parameters:

• Modulus of Elasticity (E): A measure of the stiffness of concrete, denoting the slope of the initial linear portion of the stress-strain curve.
• Poisson's Ratio: Ratio of lateral strain to axial strain in the material under stress.

5. Factors Affecting Stress-Strain Behavior:

• Concrete Composition: Includes water-cement ratio, aggregate type, and admixtures.
• Curing Conditions: Temperature, humidity, and time affect the strength and stiffness.
• Loading Rate: Speed at which load or stress is applied can influence the stress-strain characteristics.
• Age of Concrete: Properties of concrete change over time as it matures.

6. Experimental Methods:

• Standardized tests such as uniaxial compressive strength tests using cylindrical specimens are used to determine the stress-strain relations.

7. Applications and Implications:

• Understanding the stress-strain relationship is crucial for the design and analysis of concrete structures to ensure safety, durability, and performance.

These notes provide an overview of the essential aspects of the stress-strain relationship in hardened concrete necessary for further study and application in concrete technology and structural engineering.