Width of Strip Footing given Bearing Capacity Calculator

Width of Footing Formula:

\[ B = \frac{q_{fc} - (\sigma_s \times N_q)}{0.5 \times N_\gamma \times \gamma} \]

Ultimate Bearing Capacity (kPa):

Effective Surcharge (kPa):

Bearing Capacity Factor (Surcharge):

Bearing Capacity Factor (Unit Weight):

Unit Weight of Soil (kN/m³):

Width of Footing (m):

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

Definition: This calculator determines the required width of a strip footing based on soil bearing capacity, surcharge, and soil properties.

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

2. How Does the Calculator Work?

The calculator uses the formula:

\[ B = \frac{q_{fc} - (\sigma_s \times N_q)}{0.5 \times N_\gamma \times \gamma} \]

Where:

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

Explanation: The formula calculates the minimum footing width needed to distribute structural loads without exceeding the soil's bearing capacity.

3. Importance of Footing Width Calculation

Details: Proper footing width ensures structural stability, prevents excessive settlement, and complies with building codes.

4. Using the Calculator

Tips: Enter all required parameters. Default values are provided for common soil conditions. All values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: What is effective surcharge?
A: It's the additional vertical pressure at foundation level from nearby structures or soil layers above footing base.

Q2: How to determine bearing capacity factors?
A: They depend on soil friction angle - use standard geotechnical tables or soil test reports.

Q3: What's a typical unit weight for soil?
A: Typically 16-20 kN/m³ for most soils, but varies with soil type and moisture content.

Q4: Does this include safety factors?
A: No, apply appropriate safety factors to the calculated width based on local building codes.

Q5: What if my result is negative?
A: Check your inputs - negative width suggests the bearing capacity is insufficient for the given loads.