Strip Footing Capacity

This tool calculates the bearing, shear, and flexural capacity of a strip footing in accordance with CSA A23.3

Code:
CA flagCSA A23.3
B(in)

Width of footing

Constraints
min: 1step: 1
h(in)

Overall depth of cross section

Constraints
min: 1step: 1
cc(in)

Concrete clear cover to reinforcing

Constraints
min: 0step: 0.5
t_w(in)

Wall thickness

Constraints
min: 1step: 1
L_f(ft)

Footing length

Constraints
min: 1step: 1
bar/s

Reinforcing bar size and spacing for bottom flexural reinforcement

Constraints
min: 1step: 1
ϕ_c

Resistance factor for concrete

Constraints
min: 0step: 0.01
ϕ_s

Resistance factor for reinforcing steel

Constraints
min: 0step: 0.01
λ

Concrete density modification factor; 1.0 for normal density concrete

Constraints
min: 0step: 0.01
f_c(ksi)

Specified concrete strength

Constraints
min: 0step: 0.5
f_y(ksi)

Specified reinforcing steel yield strength

Constraints
min: 0step: 1
D(kip)

Dead load

Constraints
min: 0step: 1
L(kip)

Live load

Constraints
min: 0step: 1
q_a(ksf)

Allowable bearing resistance for service conditions

Constraints
min: 0step: 0.5
q_ult(ksf)

Ultimate bearing resistance

Constraints
min: 0step: 0.5
PuPudᵥ=13.2dᵥ=13.2t=12t=12h=18h=18B=36B=36qᵤ

Calculation Steps:

    Soil Bearing Stresses
    DCR = 100%
    • A_s

      Area of reinforcing steel

      in²
    • P_s

      Service load per foot of footing

      kip/ft
    • P_u

      Factored load per foot of footing

      kip/ft
    • q_s

      Service bearing demand

      ksf
    • q_u

      Factored ultimate bearing demand

      ksf
    Shear Capacity
    DCR = 29%
    • d

      Depth to primary reinforcing

      in
    • d_v

      Shear depth, normally taken as 0.9d

      in
    • β

      Cracked concrete shear factor

    • V_u

      Factored shear force at critical section

      kip
    • V_c

      Concrete contribution to shear strength

      kip
    Flexural Capacity
    DCR = 56%
    • M_u

      Factored moment

      kip-ft
    • α_1

      Stress modification factor for equivalent stress block

    • a

      Equivalent compression block depth

      in
    • M_r

      Factored flexural resistance

      kip-ft
    User Notes: