The pipe b longitudinal prestress during

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Unformatted text preview: s plus beam action d) Handling e) Transport and unloading 5.3.3 Core Thickness The core thickness shall not be less than the design thickness by more than 5 percent. The manufacturer shall declare the core thickness and the above tolerance shall be applicable to that core thickness. Permissible Stresses Tension N/mm* — Compression N/mm* Minimum residual compression of 2.5 N/mm* for upto and including pipe dia 600 mm and 1.0 N/mmz for dia above 600 mm. 0.56fi0s o.5~ ().34fik0”5 0.5 fik 0.67 N/mmz 0.5fi ().56 fik0”5 O. S&k Characteristic compressive strength of concrete at p days in N/mm*, and Characteristic compressive design strength of concrete in N/mm*. 6 JOINT DIMENSIONS Joint dimensions with tolerances for socket and spigot 3 ,, ,., i ” IS 784:2001 NOTES 1 Longitudinal stresses induced in the core during circumferential prestressing shall be treated as temporary and shall be equal to 0.284 times initial compressive stress induced in core. s 2 Forlongitudinal tressdue to beam action, a pipe shall be assumed to span its full Iengtb and suppost a total load per meter in Newtons equal to the self weight, the weight of the water in the pipe and earth load equivalent to 2.2 times the outside diameter of pipe (in r@. 3 For calculation of number of Iongitudinalsfor tnmsport and unloadingconditiorw followingbendingmoment shallbe considered foreffectivelengthofpipcs upto 5mcterand dismctcrupto600mrw Bending Moment Dia mm Nmm 200 250 Description of Loading Combination e) Operating condition + Live load (with impact) 3.04X 10’ 3.78 x 107 0.45 &k 1 The total tensile stress in the core shall be consideredas the sum of the hoop stress and flexrmdstresses, without the application of any reduction factor. 2 When calculating hoop stress, only core thickness should be cmrsidemd. When calculating ovalization flexw.alstress,the sum of the core and coating thickness should be considered. 3 For calculating bending moments and thrusts forextemal loads, Olandm’scoefficientsareto be used.The valuesforbidding angles from 30” to 180° are given in AnnexE. 4 When submitted to factory test, the mortar or concrete coated pipe shall not have cracks in the coating wider than 0.1 mm for more than 300 mm length. 7.4.2 Typical calculation for the design of longitudinal for pipe diameter 600 mm and below is given in Annex D. 7.4.3 Circumferential Prestressing Requirements The permissible stresses for various load combinations shall be as given below: 7.5 Loss of prestress in circumferential and longitudinal wires shall be calculated as per Annex F. 7.6 Typical design of prestressed concrete pipe, with winding by process of counter weightheak is given in Annex G. Permissible Stresses A . e Compression Tension N/mm2 N/mm2 o.55~ o a) Circumferential prestressing condition (Self weight + Initial prestress) 0.13 jkO’67 b) Site test condition (Site test pressure + Self weight + Weight of water + Earth fill + Final prestress) 0.13 $k0”67 c) Factory test condition...
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