Possible failure modes of a prestressed concrete containment structures (PCCS) under the action of internal pressure are hoop tension; bending plus membrane stress at extreme fiber at wall-raft junction; shear near the edge and fixture on basement; and punching shear near large penetrations like airlocks. Amongst these, hoop tension at principally membrane region is reported to be the predominant one. The paper assesses the reliability of PCCS against hoop tension failure adopting first order second moment method of level-2 reliability analysis. The performance function, g (.), was formulated on the basis of standard design format of prestressed concrete containment structure for hoop tension induced by internal pressure. Three basic variables considered are internal pressure, ultimate strength of prestressing tendons and compressive strength of concrete. Short-term as well as time dependent long-term prestressing losses are taken into account in formulating g (.). Both epistemic and aleatory uncertainties associated with basic variables are considered. It is observed from the analysis results that reliability of a prestressed concrete containment structure deteriorates with age. It is also noted that uncertainties associated with ultimate strength of prestressing cable have maximum effect on failure probability where as that due to internal pressure and compressive strength of concrete have moderate and negligible effects respectively. Rational estimation of prestressing loss is very important for safety of the containment structure over the entire operating life.
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