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Unless you are certain of the pipeline orientation, <br />the total live load in pounds, WT, must be calculated for <br />each travel orientation, and the maximum calculated <br />value must be useo in Equation 4 to calculate the live <br />load on the pipe in pounds per linear foot. <br />The LRFD requires a Lane Load, LL, of 64 pounds <br />per square foot on the top of the pipe at any depth less <br />than 8 feet. <br />The total live load acting on the pipe is <br />WT = (w + LL) LSL <br />131 <br />where: WT <br />= total live load, pounds <br />w <br />= wheel load average <br />pressure intensity, pounds <br />per square foot (at the top <br />of the pipe) <br />LL <br />= lane loading if AASHTO <br />LRFD is used, pounds per <br />square foot <br />05 H : 8, LL <br />= 64, pounds per square foot <br />Hz8,ILL <br />= 0 <br />L <br />= dimension of A parallel to <br />the longitudinal axis of pipe, <br />feet <br />SL <br />= outside horizontal span o1 <br />pipe, B, or dimension of A <br />transverse to the <br />longitudinal axis of pipe, <br />whichever ?s less, feet <br />Total Live Load in Pounds per Linear Foot <br />The total live load in <br />pounds per linear foot, WL, is <br />Figure 7 Effective Supporting Length of Pipe <br />calculated by dividing the Total Livr Load, WT, by the <br />Effective Supporting Length, Le(See Figure 7), of the <br />pipe: <br />WT <br />WL Le <br />[4] <br />where: WL = live load or, top of pipq, pounds per <br />linear foot <br />Le = effective supporting length of pipe(see <br />Figure 7), feet <br />The effective supporting length of pipe is: <br />Le = L + 1.75(3/4Ro) 151 <br />where: Rv = outside ve:2lcal Rise of pipe, feet <br />EXAMPLES <br />Four Example calculations are presented on the <br />following pages to Illustrate the four steps of the Design <br />Method, and the effect of varying the depth of fill and the <br />type of fill. The live loads per linear foot calculated in <br />the lour Examples are summarized in Table 5. <br />Soil Fill <br />O,in <br />H. ft <br />R Il s <br />Live Load, pit <br />Select Granular <br />30 <br />2 <br />16,000 <br />2559 <br />Other <br />30 <br />2 <br />16,000 <br />2672 <br />Select Granular <br />30 <br />4 <br />50,000 <br />1471 <br />Other <br />30 <br />4 <br />50,000 <br />1622 <br />Le = L + 1.75(3/48c) <br />6 1 American Concrete Npe Association • 222 W. Las Colin 1 • Irving, TX 75039 • (972) 506.7216 • FAX (972) 506-7682 <br />