Nm effective length of pipe 80 mm bending moment bm

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Unformatted text preview: ss Due to Circumferential Maximum local longitudinal tensile stress during winding (see Note 1 under 7.4.1) = 0.284 x 11.4476 8 Modulus of circular (Z2) =84 297111 mm3 section of core BM Stress due to self weight= ~ =+0.248 5 N/mm2 2 of core 28X 12.57 X1080.56 Final Precompression w,) = 0.6376 N/mm* (WC) = 6702.92 N/m Self weight of core Bending moment due to mass of core (BM) At site test Stress in longitudinal wire after losses ~,1) 158 719Nm (Z,) =113 168797mm3 BM Stress due to beam action= ~= 1 Direction G-6.5 Longitudinal Winding 1000 —=72 8 =—=23090.79x5x5x = 3.251 1 N/mmz Compressive N/mm* 3.2511 -0.6376 -0.2485 — — — I 22 I IS 784:2001 G-6.9 Load Combination of Longitudinal Stresses Under Different Condition (see 7.4.1) Actual against permissible Loading Combination Longitudinal Stresses, N/mmz + . Tensile ~-. Actual Permissible Actual a) Longitudinal prestress in barrel, (after losses) Compressive A F — b) Longitudinal prestress during winding c) Longitudinal prestress after losses plus beam action -(3.251 1 + 0.248 5)+ 1.3876 =–2.1120 –2.112 o 0.56 x (&2)0s 0.56 x 25°5 = –2.800 O Minimum residual compressive stress +1.0 (-0.637 6 + 1.361 7) = 0.7241 (-0.248 5)+ (+1.387 6) =+1.139 1 +1.139 1 < -2.8000 +1.636 1 (0.637 6 + 1.3617) =+1.361 7 -2.1503 +1.361 7 (0.248 5 + 1.387 6) =+1.636 1 +1.636 1 -0.67 < > (0.248 5 + 1.387 6) =+1.636 1 0.34 x ~Ck)0”5 0.34 x (40)05 =–2.1503 < 0.7241 d) Handling before winding Permissible — +1.361 7 -0.67 - 0.5 Xfpz 0.5 x 25 = 12.5000 < 12.5000 0.5 ‘~k 0.5 x 40 = 20.0 < 20.0 < 0.5 Xfp, ().5 x 15 = 7.50 7.50 As the diameter of pipe is above 600 mm checking for load combination of transport and unloading is not necessary. ANNEX H (Clause 7.7) TYPICAL DESIGN OF PRESTRESSED CONCRETE PIPE OF DIAMETER 1200 mm — WINDING BY PROCESS OF DIE Explanation of various symbols subsequent clauses is given in Annex J. H-1 used in Area of circumferential wire (A,) in Annex G. As= 0.623 mm2/mm Area of circumferential wire (A,) to be considered if the process for winding is die H-2 DATA Remaining data is same as considered in Annex G, except area of circumferential wire (As) being different. Ultimate tensile strength of = 1 715 N/mm2 circumferential wire Initial stress in wire during winding ~,i) (see 8.3.2) 0.65 x 1715~i = 1114.75 N/mmz Initial stress in wire during winding ~$i) in Annex G. 0.75 x 1 715&i = 1286.25 N/mmz A,= 0.623 X 1114.75 — ——. = 0.718 8mm2/mm H-3 CALCULATION OF PRESTRESS IN CORE IN CIRCUMFERENTIAL DIRECTION H-3.1 Spacing of Circumferential Wire As the process for winding is die, 4.00 mm diameter of spiral wire is reduced to 3.45 mm to get the required tension. Allowable clear spacing (see 8.4.5) 23 .. --— 1286.25 IS 784:2001 Clear spacing of spiral wire Maximum clear spacing of wire= 50 mm Minimum clear spacing of wire= 6 mm Area of spiral considered in = 0.7188 mrn2/mm design (A) Number of turns per meter length ‘0”7188 = 13-3.45 = 9.55 mm 9.5...
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