Concrete Water Tank Design Calculations

Moment Capacity Formula:

\[ M = 0.87 f_y A_{st} d (1 - \frac{f_y A_{st}}{f_{ck} b d}) \]

Yield Strength (f_y):

MPa

Steel Area (A_st):

mm²

Effective Depth (d):

Concrete Strength (f_ck):

MPa

Width (b):

Moment Capacity (M):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What Is The Moment Capacity Formula?

The moment capacity formula calculates the maximum bending moment a reinforced concrete section can resist before failure. This is essential in designing water tanks and other concrete structures to ensure they can withstand applied loads.

2. How Does The Calculator Work?

The calculator uses the moment capacity formula:

\[ M = 0.87 f_y A_{st} d (1 - \frac{f_y A_{st}}{f_{ck} b d}) \]

Where:

\( M \) — Moment capacity (N·m)
\( f_y \) — Yield strength of reinforcement steel (MPa)
\( A_{st} \) — Area of tension steel (mm²)
\( d \) — Effective depth of the section (mm)
\( f_{ck} \) — Characteristic compressive strength of concrete (MPa)
\( b \) — Width of the concrete section (mm)

Explanation: The formula calculates the moment capacity based on the balanced section concept, considering both concrete compressive strength and steel tensile strength.

3. Importance Of Moment Capacity Calculation

Details: Accurate moment capacity calculation is crucial for designing safe and efficient concrete water tanks, ensuring structural integrity under various loading conditions and preventing failures.

4. Using The Calculator

Tips: Enter all required parameters in appropriate units. Ensure values are positive and within reasonable engineering ranges for accurate results.

5. Frequently Asked Questions (FAQ)

Q1: What is the significance of the 0.87 factor?
A: The 0.87 factor accounts for the partial safety factor for steel and the relationship between design strength and characteristic strength.

Q2: When is this formula applicable?
A: This formula is applicable for under-reinforced sections where steel yields before concrete crushing occurs.

Q3: What are typical values for f_y and f_ck?
A: Typical f_y values range from 415-500 MPa for reinforcement steel, while f_ck values range from 20-40 MPa for concrete in water tank construction.

Q4: How does effective depth affect moment capacity?
A: Moment capacity increases with effective depth, as it provides a larger lever arm for the internal resisting couple.

Q5: What are the limitations of this formula?
A: This formula assumes a rectangular stress block and may not be accurate for very high-strength concretes or unusual cross-sections.