Reliability based code calibration is considered in this paper. It is described how the results of FORM based reliability analysis may be related to the partial safety factors and characteristic values. The code calibration problem is presented in a decision theoretical form and it is discussed how acceptable levels of failure probability (or target reliabilities) may be established. Furthermore suggested values for acceptable annual failure probabilities are given for the ultimate and the serviceability limit states. Finally the paper describes a procedure for the practical implementation of reliability based code calibration of LRFD based design codes.
For complex and costly decommissioning activities, it is beneficial, if not necessary, that all relevant risks are identified and assessed on an overall basis, treating and assessing all risks within the same theoretical framework. Only then may the different options be consistently compared and the risks associated with decommissioning demonstrated and documented to the different parties of interest. The present paper suggests an approach for assessing the risks associated with the decommissioning of offshore facilities. The approach takes basis in a discrete point in time representation of the considered decommissioning options where important phases of the options are represented in terms of event scenarios. Using the possibilities of Bayesian Probabilistic Networks (BPN), the failure probabilities and risk events involved in the modeling of an option may then be analyzed for each phase and added up time-wise over the entire decommissioning process. The principles of BPNs are shortly described, and the proposed approach is illustrated by an example linking the operational and structural risks in connection with a re-float decommissioning option for a concrete offshore platform. It is shown how the sensitivity may be evaluated on the basis of the BPNs, thus providing a valuable framework to first improve the risk model in terms of the representation of important scenarios, then for deciding where to apply additional safety measures most effectively, and last but not least, to demonstrate and document the contributions to the mission failure probability.
<p>Road traffic fires may have critical impact on long span bridges. Especially for suspension bridges, critical damages on the main cable and the tower can be fatal and practically not be repairable / replaceable. In Osman Gazi Bridge in Turkey, which has the main span of 1,550m and opened for traffic on 1st of July, 2016, the necessity of fire protection on the main cable was revealed through the risk analysis with ALARP principle so as to keep the temperature of main cable below 400oC against HGV (Heavy Good Vehicle) fires or hazardous materials fires, where those flame temperatures can reach up to 1,200oC. Through several trials for details, an active fire protection was selected to protect the main cable. It is the first application for the suspension bridge in the world and the paper introduces the result of risk analysis, design, trial and application of the fire protection system for the main cable of Osman Gazi bridge.</p>
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