e. Design Step : Required Thickness of Sheet Piling . 



Try 4- by 12-foot sheeting, actual thickness = 3-5- inches; 



o 



section modulus = 12 x —~ = 26.3 cubic inches; 



o 



12 

 bending stress = 1,910 x „^ , = pounds per square inch (psi) . 



Try 3- by 12-foot sheeting, actual thickness = 2-5- inches; 



o 



section modulus = 12 x -~. = 13.8 cubic inches; 



o 



u J- 4. 1,910 X 12 , ,,_ 

 bending stress = — ^ — — = 1,660 psi. 



For sheet piling of common commercial grade, the 4-inch thickness 

 should be used. 



f. Design Step : Size and Spacing of Tie Rods . The size and spacing 

 of tie rods must be compatible with the design of the wales and anchorage. 

 A spacing of 8.0 feet will be selected. 



Tie rod pull = 8 x 1,600 = 12,800 pounds. 



For Ij -inch diameter tie rod, area at root of thread = 0.89 square inch; 



12,900 ,^ ,„„ 

 tensile stress = ^ „„ = 14,400 psi. 



This conservative unit stress is desirable to allow for effects of corro- 

 sion, surcharges, unequal yield of anchorages, and other variables. 



g. Design Step : Bending Moment in Wales . 



(1) Front Wale . Maximum moment over support 



~- = 1,600 X Yq = 10,200 pounds per foot. 



Deduct 2-inch width for tie rod hole. 



For 12- by 10-foot wale, width = 11.5 - 2 = 9.5 depth = 9.5; 



9 52 

 section modulus = 9.5 x —, — = 143 cubic inches; 



6 



, ,. ^ 10,200 X 12 



bending stress = — - — =-^^= = 850 psi. 



, . ^ , , 3 1,600 X 4.0 

 horizontal shear = y x ' q— =- = 107 psi 



9.5 X 9.5 



24 



