Isolated Footing Design

Structural Footing Calculator

Design Settings

Factored Axial Load, P_u (kN)

Soil Bearing Capacity, SBC (kN/m^2)

Column Width, B (mm)

Column Depth, D (mm)

Concrete Grade, f_ck (N/mm^2)

Steel Grade, f_y (N/mm^2)

Assumed Overall Depth, D_f (mm)

Clear Concrete Cover (mm)

Main Bar Diameter (mm)

Structural Calculation Report

Step 1: Footing Plan Geometry

Working Load from Column (P)P_u / 1.5—

Total Base Load (Incl. 10% Overburden)P × 1.10—

Minimum Required AreaP_total / SBC—

Calculated Square Side Width√Area—

Rounded Side Provided (B_f)Manual Round Up—

Step 2: Ultimate Soil Pressure

Net Factored Upward Pressure (q_u)P_u / (B_f^2)—

Step 3: Flexural Bending & Balanced Depth Check

Critical Section Cantilever Projection(B_f – D_col) / 2—

Ultimate Bending Moment (M_u)q_u × B_f × proj^2 / 2—

Required Min Balanced Depth (d_bal)√(M_u / (R_lim × B_f))—

Effective Structural Depth Provided (d)D_f – CC – dia/2—

Step 4: One-Way Shear Analysis (Beam Shear)

Critical Shear Zone Distanceprojection – d—

Factored One-Way Shear Force (V_u1)q_u × B_f × L_shear—

Nominal Shear Stress (τ_v)V_u1 / (B_f × d)—

Permissible Concrete Capacity (τ_c baseline)IS Table 19 approx—

Step 5: Two-Way Shear Analysis (Punching)

Critical Perimeter Dimensions(B+d) × (D+d)—

Punching Shear Perimeter (b₀)2 × (b1 + d1)—

Factored Punching Shear (V_u2)P_u – [q_u × Area_critical]—

Punching Shear Stress (τ_v2)V_u2 / (b_0 × d)—

Permissible Punching Stress (τ_c2)0.25 × √f_ck—

Step 6: Tension Reinforcement Output

Calculated Steel Area Required (A_st)IS 456 Yield Formula—

Total Number of Bars RequiredA_st / Area_bar—

Calculated Symmetrical Mesh Spacing(B_f – 2×CC) / (Bars-1)—

Final Footing Design Summary

Footing Outer DimensionsPlan Sizing Layout—

Total Thickness (D_f)Gross Height—

Specified Clear CoverDurability Boundary—

Reinforcement Mesh ConfigurationSymmetrical Both Ways—