Design step for cantilever retaining wall YASH PAL, June 7, 2021July 12, 2025 Design steps for cantilever retaining wall – In this tutorial, we are going to design the cantilever retaining wall using the 6 steps approach.Step 1 – Set the dimensions of the walla) Depth of foundationhmin = 2b) Height of stemH = h + h minc) Base widthb0.4H to 0.6Hd) Length of toe slab = 0.3b to 0.4be) Thickness of base slab = tof) Thickness of stemgoverned by bending moment criteriacheck whether the structure is stable based on the dimension set.Step 2 – Checka) Overturning fs1 = 1.4b) Serding fs2 = 1.4otherwise, provide a shear keyc) Failure of sending soil ( base failure )= ; e = –Pmax = SBC of soilPmin = should be positive (no tension )Step 3 – Design of stemProvide main steel, distribution steel, and shear reinforcement for steel of retaining wall.Step 4 – Design of heel slabProvide main steel and distribution steel for the heel slab of the retaining wall.Step 5 – Design of the slabProvide main steel and distribution steel for the toe slab of the retaining wall.Step 6 – DetailingDetail the reinforced assignedQuestion – A cantilever retaining wall has a 5.5m tall stem to retain soil level with its top. The soil density is 16KN/m3 & has an angle of repose 30. The safe bearing capacity of soil is 210 KN/m2. Design retaining wall using M20 and Fe 415. The frictional coefficient between soil & concrete is 0.45.AnswerGivenHeight of stem = H = 5.5 mDensity of soil = 16 KN/m3Angle of repose = 30Safe bearing capacity = 210 KN/m2Coefficient of friction = 0.45M20, Fe 4151. Dimensioning of walla) Depth of foundationhmin = 2 = 1.45b) Base widthb = 0.5Hb = 0.5 x 5.5 =2.75 m 2.8 mc) Length of the slabL = 0.35hL = 0.35 x 2.8 = 0.98 m = 1 md) Thickness of base slabt = = 0.55 m 550 mmf) Thickness of stemMoment at base stem = = 147.8 KNmAultimate moment (m u ) = 1.5 x 147.8 = 221.82 KNmWe know thatmu = 0.138 fck bd 2d = = 283.5 mm 290 mmTotal depth at base of stem = 290 +60 = 350 mmReducing total depth at the top of stem be D’ = 180 mmCoefficient depth at top = 180 – 60 = 120 mm2. Tabulating force and momentCantilever Retrieving WallPa = KarH 2 = 80.67 = 147.895Checka) Overturningfs1 = = = 2.20 1.4 safeb) Servingfs 2 = = = = 1.01 1.4 not safeshear key needs to pre-providedc) Failure of undersoil= = 1.06 m ; e = – = – 1.06 = 0.34 mP max = 125.02 KN/m SBC of soilP min = 19.63 KN/m should be positive (no tension )3. Design of stemEffective depth of stem (d)= 350 – 60 = 290 mmThe maximum moment at the base of the moment (Me ) = 221.83 KNmMu = 0.87 f y Ast dMu = 0.87 x 415 x Ast x 290(main)using 4-20 mm bars @ 120 mm c/c as main reinforcementalso distribution steel = 0.12% of bd= x = 318 mm 2Using 10 mm barsSpacing = x 10 3 = 246.9 250 mmUsing 10 mm bars @ 250 mm c/c as distribution steel.Curtailment of steel ( CL 26.2.1 )Act = 940.23 mm (development length )Cutting the base at 2 m H from the base of the stemH = 5.5 – 2 = 3.5 mMoment at (h = 3.5 m) = 38.11 KN mTotal depth at h (3.5m) = 0.18 + = 0.28 mEffective depth = 0.28 – 0.06 = 0.22 = 220 mmWe knowMu = 0.87 f y Ast d57.16 x 10 6 = 0.87 x 415 x Ast x 220Ast = 776 mm 2Only half the base can be covered at 2 m from the bottomCheck for shearCritical section for shere = h 1 = 5.5 – 0.29 = 5.21 mmShear force = K a h 2 = 65.14 KNMaximum shear force () = 65.14 x 1.5 = 97.71Thickness at critical section = 0.34 m (similar)Effective depth = 0.34 – 0.06 = 0.28 m= = = 0.3489 0.35 N/ mm 2max = 2.8 N/mm 2 (for m-20)Ast = = 1.009 %= 0.62 N/mm 2 (table – 19)Here Min shear reinforcement is provided by distribution steel.4. Design of shear slabThe total depth of the heel slab = 500 mmEffective depth of heel slab = 550 – 60 = 490 mmLoad on heel slabThe total load on heel slab = 107.93 KN/mMaximum bending moment at B= – – (0.5 x (74.21 – 19.63) x 1.45 x )= 113.46 – 20.63 – 19.02 = 73.81 KNmd = = = 163.53 mm < 490 mmAst (min) = = 1003 mm2Now,Mu = 0.87 f y Ast dAst = 424.84 mm2Using 16 mm barNo. of bars = 4.96 5 barSpacing = 200 mmWe provide 5- 16 mm bars @ 200 mm c/c as the main reinforcementDistribution bars = 0.12% of bd = 660 mm2Spacing = 120 mm ( using 10 mm )We provide 10 mm dia bars @ 120 mm c/c as distribution steel5. Design of toe slabMaximum bending moment = = 56.2 KNmFactored maximum bending moment = 1.5 x 56.25 = 84.37 KNmMu = 0.138 f ck bd 2d = = 174.84 < 490 (safe)Area of steelMu = 0.87 f y Ast d84.37 x 10 6 = 0.87 x 415 x A st x 490A st = 476.53 mm 2 < A st min (1003 mm2 )We provide 5- 16 mm bars @ 200 mm c/c as the main reinforcementWe provide 10 mm dia bars @ 120 mm c/c as distribution steelCantilever Retrieving WallOther related tutorialsDesign of spherical domeDesign a rectangular beam civil engineering engineering subjects civil engineeringengineering subjects