Restrained (Basement) Retaining Wall (IBC 2024)
Design restrained (basement) retaining walls to IBC 2024 and ACI 318-19 with combined axial-flexural stem design - the check that deflection-only workflows miss. Input dead and live loads at the wall top for realistic restraint forces. Covers basement configurations the cantilever retaining wall calculator cannot handle, with Rankine at-rest or active pressure and an optional shear key.
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What it calculates
Design restrained (basement) retaining walls to IBC 2024, ASCE 7-22, and ACI 318-19. Rankine theory with at-rest or active soil pressure, combined axial-flexural stem design, footing flexural checks, and optional shear key. Input dead and live loads at the wall top for more realistic restraint forces than deflection-only workflows.
Code standards
- IBC 2024
- ASCE 7-22
- ACI 318-19
Who uses this calculator
Design restrained (basement) retaining walls to IBC 2024 and ACI 318-19 with combined axial-flexural stem design - the check that deflection-only workflows miss. Input dead and live loads at the wall top for realistic restraint forces. Covers basement configurations the cantilever retaining wall calculator cannot handle, with Rankine at-rest or active pressure and an optional shear key.
Input dead and live loads directly at the top of the wall stem to analyse combined axial-flexural effects per ACI 318-19 - producing more realistic restraint forces than deflection-only workflows. Example: an 11-foot wall without axial input may yield restraint forces exceeding 800 plf; with axial input, designs align with actual construction scenarios. Covers basement configurations the cantilever retaining wall calculator cannot handle.
How it calculates
The Restrained (Basement) Retaining Wall (IBC 2024) calculator designs propped retaining walls - typically basement walls braced at the top by a floor diaphragm - per IBC 2024, ASCE 7-22, and ACI 318-19. Rankine theory is used for lateral earth pressure and the wall stem is analysed as a propped cantilever with combined axial and lateral load.
Lateral earth pressure (Rankine theory)
Lateral soil pressure is estimated using Rankine theory. Two modes are supported:
- At-rest (K_0 = 1 - sin phi) - for walls that cannot rotate or translate at the top, which is the typical condition for basement walls braced by a floor diaphragm
- Active (K_a = tan²(45° - phi/2)) - for walls where top movement cannot be prevented
A triangular pressure distribution is assumed. Surcharge dead load and live load components contribute a uniform lateral pressure. The total lateral force is distributed between the top restraint reaction R_top and the footing reaction R_bot based on the propped cantilever model.
Stability checks
Sliding resistance is verified at the footing base:
FS_sliding = F_resist / F_slide ≥ 1.5
where F_resist combines base friction and passive soil resistance at the toe, plus optional shear key passive resistance. Maximum bearing pressure q_max is checked against the allowable bearing capacity q_a.
Stem combined axial-flexural design (ACI 318-19, Cl. 22.4 and 22.2)
The wall stem is designed as a one-way propped vertical slab. Dead and live loads at the top of the wall are combined with the lateral soil load to produce combined axial force N* and bending moment M* at the critical section. Capacity checks:
utilization (flexure) = M_u,stem / (phi × M_n,stem) ≤ 1.0 utilization (axial) = N_u,stem / (phi × N_n,stem) ≤ 1.0 utilization (shear) = V_u,stem / (phi × V_n,stem) ≤ 1.0
Combined axial-flexural interaction is checked per ACI 318-19 Cl. 22.4, ensuring the design accounts for the interaction between vertical loads and the lateral soil pressure rather than treating them independently.
Footing flexural and shear design (ACI 318-19, Cl. 22.2)
The footing is checked for moment and shear demand at the critical sections in the toe. Upward soil pressure on the heel is conservatively neglected for strength design.
utilization = M_u,ftg / (phi × M_n,ftg) ≤ 1.0 utilization = V_u,ftg / (phi × V_n,ftg) ≤ 1.0
Shear key (ACI 318-19, Cl. 14.5)
If a shear key is specified, it is aligned with the wall stem. Shear key flexural and shear capacities are checked using plain concrete provisions. The shear key passive resistance contribution is included in the sliding check.
Assumptions and scope
No soil inclination at grade. Only dead/live surcharge, wall self-weight, soil loads, and axial wall loads are considered. Wind and seismic lateral loads are excluded. Concrete detailing must be verified separately. Expansive soils are not modelled.
What engineers say
Just the simple feature of being able to link loads is a really big time-saver.
Sam Hensler
Principal, Dynamic Analysis Engineering Consulting
I like that Calcs.com shows the code reference section for each calculation and function. That means every time I use it, there's a potential for me to learn something.
Jim Fanjoy
Project Architect, Brittell Architecture
Frequently asked questions
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What are the key inputs?
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When should I use at-rest pressure instead of active pressure?
How does this IBC 2024 version differ from the IBC 2021 version?
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