Length of Footing given Bearing Capacity for Square Footing Calculator

Length of Footing Formula:

\[ L = \frac{0.3 \times B}{\left(\frac{q_f - \sigma_s}{C \times N_c} - 1\right)} \]

Width of Footing (B):

Ultimate Bearing Capacity (q_f):

kPa

Effective Surcharge (σ_s):

kPa

Cohesion in Soil (C):

kPa

Bearing Capacity Factor (N_c):

Length of Footing (L):

1. What is Length of Footing given Bearing Capacity for Square Footing?

Definition: This calculator determines the required length of a square footing based on soil bearing capacity, cohesion, and other geotechnical parameters.

Purpose: It helps civil engineers and foundation designers ensure proper footing dimensions for structural stability.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ L = \frac{0.3 \times B}{\left(\frac{q_f - \sigma_s}{C \times N_c} - 1\right)} \]

Where:

\( L \) — Length of footing (meters)
\( B \) — Width of footing (meters)
\( q_f \) — Ultimate bearing capacity (kPa)
\( \sigma_s \) — Effective surcharge (kPa)
\( C \) — Cohesion in soil (kPa)
\( N_c \) — Bearing capacity factor (dimensionless)

Explanation: The formula calculates the required footing length to support the given loads while considering soil properties.

3. Importance of Footing Length Calculation

Details: Proper footing dimensions ensure structural stability, prevent excessive settlement, and distribute loads appropriately to the underlying soil.

4. Using the Calculator

Tips: Enter all required parameters. The bearing capacity factor (N_c) defaults to 9 for typical soils. All values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: What is the ±5% tolerance for?
A: It accounts for variations in soil properties and construction tolerances.

Q2: How do I determine the ultimate bearing capacity?
A: Through geotechnical investigations including soil testing and analysis.

Q3: When would I adjust the bearing capacity factor?
A: For different soil types or based on specific geotechnical recommendations.

Q4: What's a typical cohesion value for clay soil?
A: Soft clay might be 10-25 kPa, while stiff clay could be 50-100 kPa.

Q5: Does this consider safety factors?
A: No, apply appropriate safety factors to the calculated length as per design codes.