16.1. A cantilever retaining wall is to be designed with geometry as indicated in Fig. P16.1. Backfill material is well-

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16 1 A Cantilever Retaining Wall Is To Be Designed With Geometry As Indicated In Fig P16 1 Backfill Material Is Well 1 (13.25 KiB) Viewed 35 times

16.1. A cantilever retaining wall is to be designed with geometry as indicated in Fig. P16.1. Backfill material is well-drained gravel having unit weight w = 120 pcf, internal friction angle = 25°, and friction factor against the concrete base = 0.60. Backfill placed in front of the toe will have the same properties and will be well compacted. The final grade behind the wall is level with the top of the wall, with no surcharge.

6-0 6" 12" -2-0- 10" -10-4 -5'-0"- Check the stability of the wall. (b) Design the reinforcement, specifying size and placement. Materials strengths are f: = 5000 psi and fy = 60,000 psi. Allowable soil bearing pressure is 4000 psf.

• Hints for 16.1 O 16.1 • Overturning Forces • K=0.41 • P. = 1.19 k/ft y = 2.33 ft M. = 2.78 k/ft Overturning Stability W = 3.1 k • M. = 10.2 k/ft FS = 3.66 e=2.39 ft (middle 1/3 of footing) • Factor of Safety against Sliding • Friction force F = 1.86 k/ft • FS = 1.56 . Check Soil Pressure under Footing 412 = 1208 psf Wheel = 32 psf Retaining Wall Design Using a #5 bar, d=6.7" P. = 0.88 k/ft where h = 6 ft • y=2 ft • M. = 1.6P y = 2.81 k*ft/ft • Assume a small a value like 1 in Find A -0.10 inft Find new a value and recalculate As as needed. Author uses #5 @ 12” which gives A = 0.31 in?, in excess of A, needed. So check to make sure it meets Asmin and Asmax and temperature and shrinkage requirements. • Check le for wall (should be OK) and for slab (may need a hook) • Check for temperature and shrinkage steel.

• Check shear o V. -1.6P, = 1.4 k/ft o V. = 5.34 k/ft (OK) Design Toe Assuming a constant pressure and toe extends out 2 ft from face of wall, get V. = 3.87 k/ft • M. = 3.87 k*ft/ft d-8.6 in Assume a small value of a like 1 in Find As = 0.11 in /ft Find new a value and recalculate A as needed. Author uses #5 @ 12", in excess of what is needed. So check to make sure it meets Asmin and Amex and temperature and shrinkage requirements. V. = 4.91 k/ft (OK) Check development length, will need a hook for 2 ft less 3" (clear cover) of embedment. • Design Heel • Heel must lift itself plus soil block above. Design loads are: Gheel = 0.15 k/ft2 queil = 0.72 k/ft Vu = 1.6(qheel + quoi (Thecl) = 3.02 k/ft o Mu= 1.6(qheel + soi) (thee)/2 = 3.27 k*ft/ft dheel - 8.6 in Assume a small a value like 1 in Find As-0.09 inft Find new a value and recalculate A, as needed. Author uses #5 @ 12" which gives As = 0.31 in?, in excess of As needed. So check to make sure it meets Azmin and Agmax and temperature and shrinkage requirements. • Shear calculation and development length calculations are as before for toe design.