Width of Footing given Strip Footing and Bearing Capacity Calculator

Width of Footing Formula:

\[ B_{strip} = \frac{q_f - (C \times N_c + \sigma' \times N_q)}{0.5 \times N_\gamma \times \gamma} \]

Ultimate Bearing Capacity:

Cohesion:

Bearing Capacity Factor (Cohesion):

Effective Surcharge:

Bearing Capacity Factor (Surcharge):

Bearing Capacity Factor (Unit Weight):

Unit Weight of Soil:

N/m³

Width of Footing (m):

1. What is Width of Footing Calculator?

Definition: This calculator determines the required width of a strip footing based on soil bearing capacity parameters.

Purpose: It helps civil engineers design appropriate foundation widths to ensure structural stability.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ B_{strip} = \frac{q_f - (C \times N_c + \sigma' \times N_q)}{0.5 \times N_\gamma \times \gamma} \]

Where:

\( B_{strip} \) — Width of footing (meters)
\( q_f \) — Ultimate bearing capacity (Pa)
\( C \) — Cohesion of soil (Pa)
\( N_c \) — Bearing capacity factor for cohesion
\( \sigma' \) — Effective surcharge (Pa)
\( N_q \) — Bearing capacity factor for surcharge
\( N_\gamma \) — Bearing capacity factor for unit weight
\( \gamma \) — Unit weight of soil (N/m³)

Explanation: The formula calculates the minimum footing width needed to distribute structural loads safely to the soil.

3. Importance of Footing Width Calculation

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

4. Using the Calculator

Tips: Enter all required parameters. Bearing capacity factors typically have ±5% variability. All values must be > 0 (except cohesion and surcharge which can be 0).

5. Frequently Asked Questions (FAQ)

Q1: What is ultimate bearing capacity?
A: The maximum pressure the soil can withstand without shear failure.

Q2: How do I determine soil cohesion?
A: Through laboratory tests like unconfined compression or field vane shear tests.

Q3: Why ±5% for bearing capacity factors?
A: These factors are empirically derived and have inherent variability.

Q4: What if my soil has no cohesion?
A: Enter 0 for cohesion - the calculation will use only the other parameters.

Q5: How does surcharge affect footing width?
A: Higher surcharge reduces required footing width as it contributes to bearing capacity.