Soil bearing pressure, IBC Chapter 18
Linear contact-pressure distribution from the governing ASD combination (D + 0.75L + 0.75(0.6W)), checked against the allowable soil bearing capacity.
SKL-000069 · Skill
IBC 2018ASCE 7-16Verify isolated footings geotechnically to IBC
Describe the footing geometry, unit weight, and the ASD loads at its base. Mia runs the checks you select: soil bearing pressure, sliding resistance, overturning, uplift, or highly eccentric loading, per IBC.
Mia guides you step by stepShe guides you through the inputs and explains the results.
Worked example
Footing 6.0 x 6.0 x 1.75 ft, soil bearing pressure
Bearing pressure verified- Footing
- 6.0 x 6.0 x 1.75 ft
- Horizontal load axis
- a-direction
- Self-weight
- 9.45 kip (footing) + 0.30 kip (column)
Check the soil bearing pressure of a rectangular isolated footing 6.0 x 6.0 x 1.75 ft, gamma_c = 150 pcf, column self-weight 0.30 kip, D = 60 kip, L = 25 kip, wind HW = 2.0 kip and applied moment M0 = 25 kip-ft acting 3.25 ft above the footing base, along the a-direction, allowable soil bearing capacity 2.979 ksf, per IBC (ASD).
Calculate the example with MiaKey results
- Max contact pressure qmax
- 2.959 ksf
- Allowable bearing capacity sigma_a
- 2.979 ksf
- Utilisation eta
- 0.993
Governed by the D + 0.75L + 0.75(0.6W) combination; the soil-cover weight above the footing was included in the permanent action.
- — Footing and column self-weight, and the soil cover above the footing, are added to the permanent vertical action.
Required inputs
- Footing plan dimensions a x b and thickness t, and the reinforced-concrete unit weight gamma
- Loads at the footing base: permanent (D) and live (L) vertical loads, and any wind horizontal force/moment, stated as ASD (unfactored) values
- For sliding, overturning and eccentricity: the axis the horizontal load acts along
- For bearing: allowable soil bearing capacity from a geotechnical report (never derived from soil parameters here)
- For sliding: coefficient of friction, and an optional passive earth pressure resistance
- Load combination set: ASD (IBC 1807.2.3 / ASCE 7 §2.4.1) only in this version
What you receive
- Utilisation ratio and governing ASD combination for every check you selected
- Contact pressures, safety factors, or eccentricities as applicable
- Pass/fail per selected check
Start from an input template
These templates prefill the form with typical inputs. They are not calculated results; the calculation runs in CALC.
Prepare your calculation
Configure your footing check
System sketch
m
m
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kN/m3
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kNm
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All required fields completed
Inputs completeReady to calculate
What this skill checks
Sliding resistance
Design horizontal action against base friction resistance, with an optional passive earth pressure resistance, under the reduced 0.6D + 0.6W combination.
Overturning
Edge-based stabilising vs. destabilising moment, with the lever arm matched to the loaded axis, under 0.6D + 0.6W.
Uplift
Confirms the total vertical force at the footing base remains non-negative under the governing reduced-dead-load combinations.
Highly eccentric loading
Per-axis eccentricity limit e <= dimension/6 under 0.6D + 0.6W, the governing case for the linear bearing-pressure assumption.
Normative basis
Standards & references
- IBC 2018
- ASCE 7-16
Frequently asked questions
Frequently asked questions
Does this cover LRFD (strength design) combinations?
Not in this version. Only the ASD combinations from IBC 1807.2.3 / ASCE 7 §2.4.1 are used, since geotechnical checks (bearing, sliding, overturning) are conventionally run on allowable (working-stress) values regardless of how the structure itself is designed.
Can it derive the allowable soil bearing capacity from soil parameters?
No. The allowable soil bearing capacity must come from your geotechnical report (or be supplied directly) — this skill never derives it from soil parameters.
How does this differ from the Eurocode 7 footing skill?
This skill follows IBC (ASD, US customary units); 000066-footing-verify-ec7 follows Eurocode 7 (German National Annex, SI units). Use whichever matches your project's governing code.
Ready for your first check?
Start with the example and adapt it to your structural system.
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