Laserfiche WebLink
WL = W7/LQ <br />WL = 21.035/14.3 = 1,471 pounds per linear foot <br />EXAMPLE 4 <br />Given: Same as Example 2, vxcept minimum depth of <br />fill is 4 feet. <br />Find: The maximum live load on the pipe in pounds <br />per linear fool. <br />Solution: <br />1. Review project data <br />A wall B 30-inch diameter circular concrete pipe has <br />a wall thickness of 3.5 inches, therefore B. is 3.08 <br />feet and Ro is 3.08 feet. Height of earth cover is 8 <br />feet. Use AASHTO LRFD Criteria with Other Soils <br />Fill. <br />2. Calculate average pressure intensity on the plane at <br />the top of the pipe. <br />From Table 4, the critical load, P, is 50,000 pounds <br />from two single dual wheels of two Alternate Load <br />Configurations in the passing mode, and the Spread <br />Area is: <br />A = (Spread a)(Spread b) <br />A = 0.67+4+1.00x4)(0.83+4+1.00x4) <br />A = (9.67)(8.83) <br />A = 85.4 square feet <br />w = P(I + IM)/A <br />w = 50,000(1+.165)/85.4 <br />w = 682lbIft2 <br />3. Calculate total live load acting on the pipe. <br />WT = (w + LL)LSL <br />Assuming truck travel transverse to pipe centerline. <br />LL = 64 <br />L = Spread a = 9.67 feet <br />Spread b = 8.83 feet <br />B, = 3.08 feet, which is less than Spread b, <br />therefore <br />SL = 3.08 feet <br />WT = (682 + 64)x9.67x3.08 = 22,219 pounds <br />Assuming truck travel parallel to pipe centerline <br />ILL = 64 <br />Spread a = 9.67 feet <br />L = Spread b = 8.83 feet <br />B, = 3.08 feet, which is less than Spread a, <br />therefore <br />SL = 3.08 feet <br />WT = (682 + 64)x8.83x3.08 = 20,289 pounds <br />WT Maximum = 22,219 pounds; and truck travel is <br />transverse to pipe centerline. <br />4. Calculate live load on p!pe in pounds pe: linear foot. <br />Ra = 3.08 feet <br />Lo = L+1.75(3/4Rp <br />Le = 9.67 + 1.75(0.75x3.08) = 13.7 feet <br />WL = WT/La <br />WL = 22,219/13.7 = 1,622 pounds per linear foot <br />American Concrete Pipe Association • 222 W. Las Colinas Blvd., Suite 641 • Irving, TX 75039 • (972) 506.7216 • fAX (972) 506-7682 9 <br />I:.. 1: <br />