Reliability-based calibration of reinforced concrete design formulasCerar, Benjamin (Avtor) Turk, Goran (Mentor) Yang, Yuguang (Komentor) Rózsás, Árpád (Komentor) civil engineeringmaster thesisreliability analysisstructural design codesuncertaintyStructural design codes are one of the most important components in the process of designing structures. In this thesis we deal with probabilistic calibration of existing design codes, specifically the Eurocodes. In the process of developing this thesis, we pose the following research question: What are the partial safety factors for concrete (%C) for the selected Eurocode 2 (EN 1992-1:2018 Draft 4) design expressions obtained by performing a reliability-based code calibration? To answer the question we use an implementation of a probabilistic (reliability-based) code calibration procedure, developed at TU Delft and TNO, which allows parameters of the resistance and the load effects to be considered as random variables. In this thesis, we consider the resistance model uncertainty as one of the random variables and estimate its parameters with the method of maximum likelihood using an experimental database. Reliability analysis is performed for a large number of design scenarios. The parameters of probabilistic models for the random variables are based either on literature or expert judgment. The partial factors are free parameters of a weighted objective function, which measures the absolute deviation of the calculated reliability levels from the target reliability for all design scenarios. Here we use a symmetric objective function, the target reliability %target = 4.7, which corresponds to a 1-year reference period and consequence class 2 as defined in EN 1990, and a weight function that is based on our judgment of prevalent design scenarios. The calculated sensitivity factors % 2 indicate that only the model uncertainty is a significant parameter among the resistance variables with values between 0.5 and 0.7. For other random variables on the resistance side we mostly obtain % 2 values lower than 0.2. The reliability levels mostly follow the same behavior: the values range between 3.5 and 5.0 and are the lowest when the variable load represents most of the applied load (high load ratio values). The traffic load combination shows different behavior in terms of reliability levels, with few design scenarios achieving the target reliability. To answer the research question: the calibrated material partial factors are %C = 1.54 and %C = 1.46 for the two considered subsets of the one-way shear resistance formula, %C = 1.61 and %C = 1.46 for the subsets of the punching shear resistance formula. It appears that the partial factors are close to the present value %C = 1.50, however, more research should be done to investigate the reliability level when designing according to the traffic load combination. Additionally, we recommend exploring the calibration for different levels of target reliability, as well as performing a sensitivity analysis in order to determine whether it makes sense to include the random variables that show low % 2 values in the calibration.[B. Cerar]20202020-11-04 16:07:30Magistrsko delo/naloga121870sl