1. What is the Stiffness Coefficient?

The stiffness coefficient (k) for concrete represents the resistance of a structural element to deformation under load. It is calculated as the product of cross-sectional area and modulus of elasticity divided by the length of the element.

2. How Does the Calculator Work?

The calculator uses the stiffness coefficient formula:

Where:

• \( A \) — Cross-sectional area (m²)
• \( E \) — Modulus of elasticity for concrete (Pa)
• \( L \) — Length of the element (m)

Explanation: The formula calculates how much force is required to produce a unit displacement in the structural element.

3. Importance of Stiffness Coefficient

Details: The stiffness coefficient is crucial in structural engineering for analyzing deflection, vibration characteristics, and load distribution in concrete structures.

4. Using the Calculator

Tips: Enter the cross-sectional area in square meters, modulus of elasticity in Pascals, and length in meters. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical modulus of elasticity for concrete?
A: For normal strength concrete, E typically ranges from 14,000 to 41,000 MPa (14-41 GPa), depending on the concrete mix and strength.

Q2: How does stiffness affect structural design?
A: Higher stiffness reduces deflection under load but may increase seismic forces. Proper stiffness balancing is essential for structural performance.

Q3: Does the formula apply to reinforced concrete?
A: For reinforced concrete, the transformed section properties should be used to account for both concrete and steel contributions.

Q4: How does concrete age affect stiffness?
A: Concrete stiffness increases with age as the material continues to hydrate and gain strength over time.

Q5: Are there limitations to this simple formula?
A: This formula provides axial stiffness only. For bending stiffness, different formulas considering moment of inertia are required.