AASHTO
AASHTO LRFD 2024 — Extreme Event I, φ 0.9
AASHTO LRFD Bridge Design Specifications, 10th ed. (2024)Revision 2Required FoS ≥ 1Seismic design situation
Use it in Slope
In a design, choose it under Analyze → Design factor set, and the PDF report runs it too.
Checked against the standard · Not yet validated
Known limitations
- γEQ = 0.5 (C3.4.1 commentary) on the live surcharge; it is project-specific: edit it in a custom copy.
- kh = As (×1.2 on Site Class A, B or B/C) and may be halved where the wall can move 1–2 in. (11.6.5.2); kv is normally 0.
- φ divides soil strength only, inside the solve.
- Reinforcement takes its own φ (C11.10.5.6, C11.6.3.7); alternatives to the values used need a custom copy: mild-steel tendon 0.90, preliminary anchor pull-out 0.65 / 0.70 / 0.50, Grade 75 nail bar 0.75, steel grid on a flexible facing 0.75.
- A geosynthetic layer needs its product reduction factor RF = RFID·RFCR·RFD on the element; a metallic layer's capacity is its corroded section's, entered as characteristic.
- Piles have no AASHTO slope-stability resistance factor and are unfactored. Reinforced soil slopes are outside AASHTO LRFD (FHWA GEC 11).
Values
Actions
| Soil weightγ | Unfavorable | ×1.00 |
| Favorable | ×1.00 | |
| Permanent loadγG | Unfavorable | ×1.00 |
| Favorable | ×0.00 | |
| Variable loadγQ | Unfavorable | ×0.50 |
| Favorable | ×0.00 | |
| Seismic coefficientγE | ×1.00 | |
Resistance
| Earth / global resistanceγRe | ×0.90 | |
Materials
| Effective cohesionγc′ | ×1.00 | |
| Friction (tanφ′)γφ | ×1.00 | |
| Undrained strength (cu)γcu | ×1.00 | |
| Shear strength (other models)— | ×1.00 | |
Reinforcement
| Anchor — tendonγt | ×1.00 | |
| Anchor — pull-outγpo | ×1.00 | |
| Nail — barγt | ×0.65 | |
| Nail — head plateγp | ×0.90 | |
| Nail — pull-outγpo | ×0.65 | |
| Geosynthetic — ruptureγt | ×1.00 | |
| Geosynthetic — pull-outγpo | ×1.00 | |
| Steel strip — ruptureγt | ×1.00 | |
| Steel strip — pull-outγpo | ×1.20 | |
| Steel grid — ruptureγt | ×0.85 | |
| Steel grid — pull-outγpo | ×1.20 | |
Sources
Document: AASHTO LRFD Bridge Design Specifications, 10th ed. (2024)
Actions
| Factor | Value | Source |
|---|---|---|
| Soil weight — unfavorable | ×1.00 | 3.4.1, Table 3.4.1-1, Extreme Event I: EV 1.00, PDF p82 · Not yet validated |
| Soil weight — favorable | ×1.00 | 3.4.1, Table 3.4.1-1, Extreme Event I: EV 1.00, PDF p82 · Not yet validated |
| Permanent load — unfavorable | ×1.00 | 3.4.1, Table 3.4.1-1, Extreme Event I: DC … ES 1.00, PDF p82 · Not yet validated |
| Permanent load — favorable | ×0.00 | 3.4.1, an external load that contributes to stability is not included, PDF p79 · Not yet validated |
| Variable load — unfavorable | ×0.50 | 3.4.1, C3.4.1, γEQ, PDF p84 · Slope convention · Not yet validated — γEQ is project-specific; the commentary's 0.50 is used (past practice 0.0). Edit it in a custom copy. |
| Variable load — favorable | ×0.00 | 3.4.1, an external load that contributes to stability is not included, PDF p79 · Not yet validated |
| Seismic coefficient | ×1.00 | 3.4.1, Table 3.4.1-1, Extreme Event I: EQ 1.00, PDF p82 · Not yet validated |
Materials
| Factor | Value | Source |
|---|---|---|
| Effective cohesion | ×1.00 | 11.5.8, PDF p1490 · Not yet validated |
| Friction (tanφ′) | ×1.00 | 11.5.8, PDF p1490 · Not yet validated |
| Undrained strength (cu) | ×1.00 | 11.5.8, PDF p1490 · Not yet validated |
| Shear strength (other models) | ×1.00 | 11.5.8, PDF p1490 · Not yet validated |
Resistance
| Factor | Value | Source |
|---|---|---|
| Earth / global resistance | ×0.90 | 11.5.8, overall stability with earthquake loading, PDF p1490 · Not yet validated |
Reinforcement
| Factor | Value | Source |
|---|---|---|
| Anchor — tendon | ×1.00 | 11.5.8, all resistance factors 1.0 unless specified, PDF p1490 · Not yet validated |
| Anchor — pull-out | ×1.00 | 11.5.8, all resistance factors 1.0 unless specified, PDF p1490 · Not yet validated |
| Nail — bar | ×0.65 | 11.12.7.2, bar, Grade 150, PDF p1605 · Slope convention · Not yet validated — The conservative grade value is used; Grades 60–80 take 0.75 in a custom copy. |
| Nail — head plate | ×0.90 | 11.12.7.2, facing, PDF p1605 · Not yet validated |
| Nail — pull-out | ×0.65 | 11.12.7.2, pull-out, PDF p1605 · Not yet validated |
| Geosynthetic — rupture | ×1.00 | 11.5.8, geosynthetic tensile and pull-out, PDF p1490 · Not yet validated |
| Geosynthetic — pull-out | ×1.00 | 11.5.8, geosynthetic tensile and pull-out, PDF p1490 · Not yet validated |
| Steel strip — rupture | ×1.00 | 11.5.8, strip reinforcement, PDF p1490 · Not yet validated |
| Steel strip — pull-out | ×1.20 | 11.5.8, pull-out of metallic reinforcement, PDF p1490 · Not yet validated |
| Steel grid — rupture | ×0.85 | 11.5.8, grid reinforcement, PDF p1490 · Not yet validated |
| Steel grid — pull-out | ×1.20 | 11.5.8, pull-out of metallic reinforcement, PDF p1490 · Not yet validated |