2400 33RD ST CRANE LOADING 2018-01-02 MF Import

HS 20 dual wheel, since at 16,000 pounds it applies a greater load than the 12,500 pound Alternate Load(Figures 2 and 3). At intermediate depths, the maximum pressure will be developed by the wheals of two HS 20 trucks in the passing mode, since at 16,000 pounds each, the two wheels apply a greater load than the 12,500 pounds of an Alternate Load wheel(Figures 2 and 4). At greater depths, the maximum pressure will be developed by wheels of two Alternate Load configuration trucks in the passing mode, since at 12,500 pounds each, the four wheels apply the greatest load (50,000 pounds)(Figures 2 and 5). Intermediate depths begin when the spread area of dual wheels of two HS 20 trucks in the passing mode meet and begin to overlap. Greater depths begin when Ilia spread area b of two single dual wheels of two Alternate Load configurations in the passing mode meet and begin to overlap. Since the exact geometric relationship of individual or combinations of surface wheel loads cannot be anticipated, the most critical loading configurations along with axle loads and rectangular spread load area are presented in Tables 3 and 4 for the two AASHTO LRFD soil types. DESIGN METHOD The design method encompasses 4 steps. 1. Obtain the following project data: Pipe shape, size and wall thickness. Height of cover over the concrete pipe, and type of earth fill. LRFD or other criteria. 2. Calculate the average pressure intensityofthewheel loads on the soil plane on the outside top of the pipe. 3. Calculate the total live wheel load and lane foad acting on the pipe. 4. Calculate the total live load acting on the pipe in pounds per linear fool. Project Data Pipe shape and internal dimensions are shown on the project plans. Complete information on dimensional details are included in ASTM Specification C 14 for nonreinforced circular concrete pipe(8), C 76 for reinforced concrete circular pipe(g), C 506 for reinforced concrete arch plpe(10) and C 507 for reinforced concrete elliptical pipe(11). Internal size, wall thickness and outside dimensions are presented in Tables 6, 7 and 8 for circular, arch and elliptical pipe respectively. The minimum earth cover over the concrete pipe can be obtained from the project plans. The type of fill material required under, around and over the concrete pipe will be noted on the project plans or detailed in the contract documents. A decision regarding whether the AASHTO LRFD or other criteria will be used should be obtained from the project authority. Average Pressure Intensity The wheel load average pressure intensity on the subsoil plane at the outside top of the concrete pipe is: w= Pit +IM (2) A where: w = wheel load average pressure intensity, pounds per square foot P = total live wheel load applied at the surface, pounds A = spread wheel load area at the outside top of the pipe, square feet IM = dynamic load allowance From the appropriate Table 3, or 4, select the critical wheel load and spread dimensions for the height of earth cover over the outside top of the pipe, H. The spread live load area is equal to Spread a times Spread b. Select the appropriate dynamic load allowance, using Equation Total Live Load A designer is concerned with the maximum possible loads, which occur when the distributed load area is centered over the buried pipe. Depending on the pipe size and height of cover, the most critical loading orientation can occur either when the truck travels transverse or parallel to the centerline of the pipe. Figure 6 illustrates the dimensions of the spread load area, A, as related to whether the truck travel is transverse or parallel to the centerline of the pipe. Spread b it i1 —r— A � I ' I I DirI lon,of o I Have I uCL t-- — --g —U) I I o Spread a I —�-- I � Pipe m a ,Pipe o Centerline m American Concrete Pipe Association • 222 W. Las Colinas Bind, Suite 641 • Irving, Tx 75039 • (972)'506.7216 • FAx (972) 506.7682 5. Design Data 1