Reliability of a corroded RC beam based on Bayesian updating of the corrosion model

RC structures degrade primarily due to corrosion-induced damages, mostly by the loss of steel rebar volume. The prediction of time-varying damage due to corrosion is important for assessing the residual life of a structure and making decisions on maintenance/repair. Existing models of prediction fail to provide realistic estimates of steel loss over time. This paper presents a new methodology for the corrosion reliability analysis of reinforced concrete components, where the corrosion loss is estimated employing Bayesian updating using field measurements, which also incorporates instrument biases and errors in the NDT evaluations. Based on compiled experimental results, the updated model provides significantly improved estimation of steel loss over time. Sample reliability analyses over the design life of a corroded RC beam show the importance of updating over the existing model, for both pitting and uniform corrosion considerations. (C) 2016 Elsevier Ltd. All rights reserved

Seismic fragility analysis of a typical Indian PHWR containment: Comparison of fragility models

The necessity of performing a detailed seismic fragility analysis of nuclear power plant components is well established in the nuclear industry. This paper focuses on the seismic fragility analysis of the primary containment structure of a typical Indian 700 MWe PHWR. The primary emphases of the fragility analysis adopted here are the detailed nonlinear modelling along with time-history analyses and the consideration of displacement-based failure limits. Three IDA-based methods and the conventional method using scaling/safety factors are used for fragility analysis and their results are compared. Among these, a new regression-based method proposed in this work provides better results than the existing methods. A modified version of this new method for estimating fragilities for multiple limit states simultaneously also provides similar results while reducing the level of statistical computation. The conventional method of fragility analysis fails to capture the (aleatory) randomness properly. In addition, compared to the peak ground acceleration, the fundamental mode spectral acceleration is found to have a better correlation with the damage measure for this structure, and is recommended for independent fragility analysis of such structures. (C) 2015 Elsevier Ltd. All rights reserved

The impact of surgical delay on resectability of colorectal cancer: An international prospective cohort study

AimThe SARS-CoV-2 pandemic has provided a unique opportunity to explore the impact of surgical delays on cancer resectability. This study aimed to compare resectability for colorectal cancer patients undergoing delayed versus non-delayed surgery.MethodsThis was an international prospective cohort study of consecutive colorectal cancer patients with a decision for curative surgery (January-April 2020). Surgical delay was defined as an operation taking place more than 4 weeks after treatment decision, in a patient who did not receive neoadjuvant therapy. A subgroup analysis explored the effects of delay in elective patients only. The impact of longer delays was explored in a sensitivity analysis. The primary outcome was complete resection, defined as curative resection with an R0 margin.ResultsOverall, 5453 patients from 304 hospitals in 47 countries were included, of whom 6.6% (358/5453) did not receive their planned operation. Of the 4304 operated patients without neoadjuvant therapy, 40.5% (1744/4304) were delayed beyond 4 weeks. Delayed patients were more likely to be older, men, more comorbid, have higher body mass index and have rectal cancer and early stage disease. Delayed patients had higher unadjusted rates of complete resection (93.7% vs. 91.9%, P = 0.032) and lower rates of emergency surgery (4.5% vs. 22.5%, P ConclusionOne in 15 colorectal cancer patients did not receive their planned operation during the first wave of COVID-19. Surgical delay did not appear to compromise resectability, raising the hypothesis that any reduction in long-term survival attributable to delays is likely to be due to micro-metastatic disease