For unbonded systems, the analysis indicated that the sample size recommended by the CSA Standard (4% of the tendon population) is adequate. It was found that flexural testing is useful in updating the probability of concrete cracking under accident pressure. For bonded systems, the test is carried out on an unbonded test beam that matches the section geometry and material properties of the containment structure. For unbonded systems the tests are carried out on a randomly selected sample from each tendon group in the structure. As specified in CSA-N287.7, the evaluation of prestressing systems for containment structures is based on the results of lift-off tests to determine the prestressing force. An annual target reliability of 10 -4 was used for this limit state. Therefore, the evaluation of prestressing inspection programs was based on their effectiveness in maintaining an acceptable reliability level with respect to a limit state representing yeilding of non- prestressed reinforcement. Prestressing force losses (due to creep and shrinkage, stress relaxation or tendon corrosion) can lead to tensile stresses under accident pressure, resulting in loss of containment leak integrity due to concrete cracking and tensile yielding of the non- prestressed reinforcement. The main function of the prestressing system is to ensure the leak integrity of the containment by maintaining a compressive state of stress under the tensile forces which arise in a hypothesized loss of coolant accident. Reliability-based inspection of prestressed concrete containment structuresĪ study was undertaken to develop a reliability-based approach to the planning of inspection programs for prestressed concrete containment structures. The sensitivities of the Choleskey decomposition matrix and the natural vibration character are calculated by simplified procedures. The limit state surface of the prestressed concrete containment is constructed directly incorporating the prestress.

Limit state probabilities for given parameters are calculated using the procedure developed at BNL, while that with consideration of parameter uncertainties are calculated by a fast integration for time variant structural reliability.

The reliability analysis of prestressed concrete containment structures subjected to combinations of static and dynamic loads with consideration of uncertainties of structural and load parameters is presented. International Nuclear Information System (INIS) Reliability analysis of prestressed concrete containment structures

Tendon primary midas civil