Gravity & Cantilever Retaining Wall Design Excel Workbooks
DOMAINStructural Engineering, Geotechnical, RCD
TOOLS & TECHNIQUESMicrosoft Excel, Rankine Earth Pressure Method, Moment Equilibrium Formulations, P-M Interaction
Conducted for Reinforced Concrete Design II, this project built dynamic calculation workbooks in Excel for mass gravity and reinforced-concrete cantilever retaining walls with and without shear keys.
Key Engineering Scope
- Lateral Earth Pressures: Automated Rankine active pressure calculations considering 13 ft retained height, soil friction angle (32°), unit weight (130 pcf), and surface surcharge.
- Equilibrium & Stability Checks: Coded automated formulas verifying safety factors against overturning (FS ≥ 2.0), sliding (FS ≥ 1.5), and bearing eccentricity within middle thirds.
- Shear Key Engagement: Evaluated passive soil resistance enhancements from an embedded 1.5 ft × 2.0 ft shear key, increasing sliding stability margins.
- Cantilever Structural Detailing: Computed flexural and shear reinforcement for the stem (#7 @ 11” c/c), heel slab (#8 @ 14” c/c), toe slab, and vertical curtailment intervals.
EXCEL DESIGN SPREADSHEETS
Interactive Engineering Calculation Sheets
| # | A (Parameter) | B (Value / Unit) | C (Design Check) | D (Status) |
|---|---|---|---|---|
| 1 | 1. DESIGN PARAMETERS & GEOMETRY | |||
| 2 | Total Retained Height (H) | 16.0 ft | Stem: 14.5 ft | Base: 1.5 ft | Specified |
| 3 | Stem Top Width | 1.25 ft (15 in) | Stem Bottom Width = 1.25 ft | Adopted |
| 4 | Base Slab Width (L) | 10.25 ft | Toe: 3.40 ft | Heel: 5.60 ft | Proportioned |
| 5 | Concrete Strength (fc') | 3,000 psi | Steel Yield (fy) = 60,000 psi | Material |
| 6 | Soil Unit Weight (γsoil) | 130 pcf | Concrete Unit Weight = 145 pcf | Soil |
| 7 | Internal Friction Angle (Φ) | 32° | Ka = (1 - sinΦ)/(1 + sinΦ) = 0.307 | Calculated |
| 8 | Allowable Bearing Capacity (qa) | 4,000 psf | Base Friction Coefficient (f) = 0.50 | Geotech |
| 9 | 2. STABILITY & SAFETY FACTOR CHECKS | |||
| 10 | Overturning Moment Check | FS = 2.68 | Allowable FS ≥ 2.00 | OK! |
| 11 | Sliding Resistance Check | FS = 1.504 | Allowable FS ≥ 1.50 | OK! |
| 12 | Eccentricity & Resultant Location | a = 4.76 ft > L/3 (3.42 ft) | Resultant within middle third | OK! |
| 13 | Toe Soil Bearing Pressure (q1) | 1,818 psf | qa = 4,000 psf (q1 < qa) | OK! |
| 14 | Heel Soil Bearing Pressure (q2) | 1,183 psf | q2 > 0 (No tension uplift) | OK! |
| 15 | 3. STRUCTURAL REINFORCEMENT DETAILS | |||
| 16 | Stem Vertical Flexural Steel (Inside) | As = 0.61 in²/ft | #7 @ 11" c/c | OK! |
| 17 | Stem Vertical Steel (Outside Face) | As = 0.23 in²/ft | #6 @ 23" c/c | OK! |
| 18 | Stem Horizontal Steel (Outside 2/3) | As = 0.30 in²/ft | #4 @ 7" c/c | OK! |
| 19 | Stem Horizontal Steel (Inside 1/3) | As = 0.15 in²/ft | #4 @ 15" c/c | OK! |
| 20 | Stem Shear Capacity Check | Vu = 6,719 lb < ΦVc (12,324 lb) | Shear reinforcement not required | OK! |
| 21 | Heel Slab Main Top Steel | As = 0.63 in²/ft | #8 @ 14" c/c | OK! |
| 22 | Heel Slab Temp & Shrinkage Steel | As = 0.31 in²/ft | #6 @ 16" c/c | OK! |
| 23 | Toe Slab Main Bottom Steel | As = 0.58 in²/ft | #8 @ 16" c/c | OK! |
| 24 | Toe Slab Temp & Shrinkage Steel | As = 0.31 in²/ft | #6 @ 16" c/c | OK! |
| # | A (Parameter) | B (Value / Unit) | C (Design Check) | D (Status) |
|---|---|---|---|---|
| 1 | 1. GEOMETRY WITH SHEAR KEY | |||
| 2 | Total Retained Height (H) | 16.0 ft | Stem: 13.5 ft | Base: 2.5 ft | Adopted |
| 3 | Shear Key Depth & Width | 1.5 ft depth x 2.0 ft width | Provides passive soil resistance | Enhanced |
| 4 | Base Slab Width (L) | 11.0 ft | Toe: 4.70 ft | Heel: 6.30 ft | Proportioned |
| 5 | 2. STABILITY WITH PASSIVE RESISTANCE | |||
| 6 | Overturning Moment Check | FS = 3.12 | Allowable FS ≥ 2.00 | OK! |
| 7 | Sliding Resistance with Key | FS = 1.95 | Passive earth pressure engaged (FS ≥ 1.50) | OK! |
| 8 | Eccentricity & Bearing Check | qmax = 2,150 psf | qa = 4,000 psf (qmax < qa) | OK! |
| 9 | 3. REINFORCEMENT & STRUCTURAL INTEGRITY | |||
| 10 | Stem Vertical Steel (Inside Face) | #8 @ 10" c/c | Flexural safety verified | OK! |
| 11 | Stem Shear Capacity Check | Vu < ΦVc | Concrete shear capacity adequate | OK! |
| 12 | Shear Key Reinforcement | #6 @ 12" c/c ties | Dowel extension into base slab | OK! |
| 13 | Heel Slab Main Top Steel | #8 @ 12" c/c | Bending under soil mass | OK! |
| 14 | Toe Slab Main Bottom Steel | #8 @ 14" c/c | Bending under soil upward reaction | OK! |
| # | A (Parameter) | B (Value / Unit) | C (Design Check) | D (Status) |
|---|---|---|---|---|
| 1 | 1. GRAVITY WALL PROPORTIONS | |||
| 2 | Total Wall Height (H) | 16.0 ft | Height Retained: 13 ft | Undersoil: 3 ft | Specified |
| 3 | Top Width | 1.5 ft | Base Width = 8.0 ft | Trapezoidal |
| 4 | Concrete Unit Weight | 145 pcf | Plain / Mass Concrete Wall | Material |
| 5 | Soil Unit Weight | 130 pcf | Internal Friction Angle Φ = 32° | Soil |
| 6 | Surcharge Load | 400 lb/ft | Equivalent soil height evaluated | Traffic / Live |
| 7 | 2. EQUILIBRIUM & STABILITY CHECKS | |||
| 8 | Safety Factor Against Overturning | FS = 2.45 | Mr / Mo ≥ 2.00 | OK! |
| 9 | Safety Factor Against Sliding | FS = 1.62 | μ ΣV / ΣH ≥ 1.50 | OK! |
| 10 | Eccentricity Verification | e = 1.12 ft < B/6 (1.33 ft) | Resultant within middle third (No tension) | OK! |
| 11 | Maximum Base Bearing Pressure | qmax = 3,420 psf | qa = 4,000 psf (qmax < qa) | OK! |
| # | A (Parameter) | B (Value / Unit) | C (Design Check) | D (Status) |
|---|---|---|---|---|
| 1 | 1. GRAVITY WALL WITH SHEAR KEY | |||
| 2 | Total Wall Height (H) | 16.0 ft | Top Width: 1.5 ft | Base Width: 7.0 ft | Optimized |
| 3 | Shear Key Dimensions | 1.5 ft depth x 2.0 ft width | Key below base level | Embedded |
| 4 | Allowable Bearing Capacity | 8,000 psf | Dense soil / gravel strata | Geotech |
| 5 | 2. STABILITY CHECKS WITH PASSIVE FORCE | |||
| 6 | Safety Factor Against Overturning | FS = 2.80 | Overturning resistance verified | OK! |
| 7 | Safety Factor Against Sliding | FS = 2.10 | Shear key passive resistance active | OK! |
| 8 | Bearing Capacity Safety | qmax = 4,110 psf | qa = 8,000 psf (qmax << qa) | OK! |