1. What is Width of Square Footing given Bearing Capacity?

Definition: This calculator determines the required width of a square footing based on soil bearing capacity and other geotechnical factors.

Purpose: It helps civil engineers and construction professionals design appropriate foundation dimensions for structural stability.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( B \) — Width of footing (meters)
• \( q_{fc} \) — Ultimate bearing capacity in soil (kPa)
• \( \sigma_s \) — Effective surcharge (kPa)
• \( N_q \) — Bearing capacity factor dependent on surcharge (±5%)
• \( N_\gamma \) — Bearing capacity factor dependent on unit weight (±5%)
• \( \gamma \) — Unit weight of soil (kN/m³)

Explanation: The formula calculates the minimum footing width required to prevent soil failure under structural loads.

3. Importance of Footing Width Calculation

Details: Proper footing width ensures structural stability, prevents excessive settlement, and maintains safety factors in foundation design.

4. Using the Calculator

Tips: Enter all required parameters with appropriate units. Bearing capacity factors typically have ±5% variability.

5. Frequently Asked Questions (FAQ)

Q1: What is effective surcharge?
A: It's the additional vertical pressure at foundation level from surrounding soil or adjacent structures.

Q2: How do I determine bearing capacity factors?
A: These depend on soil friction angle - consult geotechnical tables or soil test reports.

Q3: Why is there a 0.4 factor in the formula?
A: This accounts for the shape factor for square footings in bearing capacity theory.

Q4: What if my soil has cohesion?
A: This calculator is for cohesionless soils. For cohesive soils, a different formula is needed.

Q5: Should I apply safety factors to the result?
A: Yes, typical practice is to divide the ultimate capacity by a safety factor (usually 2.5-3).

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