F clauses 75 g 3 and j 422 1 loss of prestress f 1

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Unformatted text preview: ty of high tensile wire. . 2.00 x 105N/mm2 (for stress relieved), and = 1.93 x 10s N/mm2 (for as drawn). L= Initial stress in core in circumferential wire in N/mm*. Effective length mm. of pipe in mm + 80 NOTE— Lossof stress in high tensile wire at factory test pressure will be 90 pereent of the total losses. ANNEX G (Clauses 7.6, H-3.3 and J-5) TYPICAL DESIGN OF PRESTRESSED CONCRETE PIPE OF DIA 1200 mm — WINDING PROCESS OF COUNTER WEIGHT/BREAK Process for winding G-1 Explanation of various symbols used in subse- quent clauses is given in Annex K. Counter Weight/ Break = 70 mm = 22 mm = 1.984 m Core thickness, T, Coat thickness, Th Width of trench (D+ 2TC+ 2T~+ 600), B, =4mm Diameter of circumferential wire, d~ = 4mm Diameter of longitudinal wire, dC = 28 Number of longitudinal, N = 1 715 N/mm2 Ultimate tensile strength of circumferential wire (see 4.5.1) = 1 715 N/mm2 Ultimate tensile strength of longitudinal wire (see 4.5.1) Area of circumferential wire, A, = 0.623mm2/mm Modulus of elasticity of steel, E, = 20x104 N/mm* G-2 DATA = 1200 mm Diameter of pipe, D = 5.0 m Effective length of pipe, L Working pressure, PW(see 3.4) = 0.700 N/mm* = 1.050 N/mm2 Site test pressure, P, = 1.150 Nhnrn2 Factory test pressure, P~ = 1.00m Height of fill, H = 19700 N/m3 Density of fill material, K, Class AA (IRC) Live load G-3 ASSUMPTIONS Density of core concrete, KC Density of coating, Kb Density of water, KW BY = 24000 N/m3 = 21600 N/m3 = 10000 N/m3 17 IS 784:2001 = 4X 10A N/rnrn2 Modulus of elasticity of concrete, E .5 Modular ratio; n Minimum compressive strength of core concrete (spun) at various stages a) Characteristic compressive = 40 N/mm* design strength, ~, b) At winding, ~, (see 8.4.1) = 25 N/mm’ c) At detensioning longitu= 15 N/mm* dinals ~, (see 8.3.2) Losses at factory test 0.9 x Total 10SS ().9 = 1286.25 – 169.34 fif= Wire r= D+~+Tb N/mmz = 646 mm 2 d) Modulus of section for circumferential stress (Z) Z= 1/6x (TC+Tb)2X 1000 = 1410667mm3/m e) Sectional area (A) A=(TC+TJXIOOO = 92000 mm2 f) Modulus of circular section of core (Z2) Stress Induced iu Core 3.1416 ~ 0DP4 -D4 =84297111mm3 32 ODC g) Modulus of circular section of pipe (Zl) = 11.4476 N/mm2 3.1416 XODP4– D4 32 G-4.3 Loss of Stress in Wire (see Annex E) 1 Elastic deformation ).2 X~i=3.2 x 11.4476 b) 1 Relaxation of wire ().08 X&i = 0.08 x 1286,25 c) 1 Deformation due to creep 2.5 X 11.4476 9.9405 at a) Outside diameter of core (ODC) ODC=D+2XTC = 1340mrn b) Outside diameter of pipe (ODP) ODP=D+2XTC+2XTb = 1384mm c) Mean radius of pipe (r) Clear spacing of spiral = 16.17 mm wire is 20.17– 4 16.17 mm is in between 50 mm and 6 mm. Hence, the area of spiral (A,) considered is correct. Initial stress in wire during winding ~i) (see 8.4.2) 0.75 x 1715 = 1 286.25N/mm2 70 0.623 —To .&=+ in Core G-4.5 Section Constant =20,17 mm 0.623 Induced 0.623 — To & = + 9.7731 N/mmz ~,=1098.10x 1000 .— 49.57 . 1 286.25 X — l116.91x Stress G-4.4.1 Compressive Stress in Core at Site Test...
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