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Test condition site test pressure self weight weight

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Unformatted text preview: (Factory test pressure + Self weight + Weight of water + Pre-stress at factory test) d) Operating condition O (Working pressure+ Self weight + Weight of water + Earth fill + final prestress) 0.13 fik0”67 where f, = Characteristic compressive strength of concrete at p days in N/mm2. Characteristic compressive design strength of concrete in Nhnm2. NOTES 4.59 XI07 300 5.45 x 10’ 350 6.37 x 107 400 450 7.36 X 107 8.44 X107 500 11.08 xIt)’ 600 [email protected] havingeffectivelengthmorethan5 w thebendingmoment shall be multipliedby a factor(L/5~, whereL is the effectivelength of pipe. Forpipesabove600 mm diameter,no specialconsideration is necessary,The minimum number of Iongitudinalsfor4 m and 5 m long pipes shall be 12and 16respectively. [email protected] of Loading Combination Permissible Stresses . / Tension Compression N/mm2 N/mm2 ‘7.7 Typical design of prestressed concrete pipe with winding by process of die is given in Annex H. 7.8 Typical design of prestressed concrete pipe for drainage, sewerage and culverts is given in Annex J. 7.9 Design Criteria for Cylinder Pipes ().45&k The pipes shall be designed to meet the following conditions: Description of Loading Combination 0.45 ~k a) Circumferential prestressing condition (Self weight + Initial prestress) b) Site test condition (Site test pressure + Self weight + Weight of water+ Earth fill + Final prestress) ().45fik 4 Permissible Stresses Tension N/mm2 o 0.38 fik0”67 Compression N/mm2 0.55 & o.45fik IS 784:2001 Description of Loading Combination Tension N/mm* c) Operating condition (Working pressure+ Self weight + Weight of water + Earth fill + Final prestress) that concrete will be evenly distributed. The same is sufficiently compacted at the specified thickness throughout the length of the pipe. After the concrete has been deposited, the rotation shall be continued at an increased speed, for a length of time sufficient to provide the specified strength, sufficient compaction and bond; to permit handling of the mould from the spinning machine, without damage to the pipe core. Excess water and laitance shall be removed from the interior surface of the pipe in an approved manner so that the surface is solid, straight and true. Permissible Stresses > Compression N/mmz o d) Operating condi- o.38jk0”67 tion + Live load (with impact) o.45fik ().45&k 8.2 Curing of Core and Cover Coat The curing of the concrete core and that of cover coat shall be in two separate operations. The curing for core shall be for a period, till it attains the required strength. where f. r = Characteristic commessive strength of concrete at p days in N/mmz. (k = Characteristic compressive design strength of concrete in N/mrn2. Curing shall be either by steam or by water or by a combination of steam and water, or by use of approved curing compounds. Coating shall be cured for a minimum period of 7 days, if water curing is used. If steam curing is used for coating, after that it should be water cured for at least 3 d...
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