@article{ChowdhuryKraus, author = {Chowdhury, Sharmistha and Kraus, Matthias}, title = {Design-related reassessment of structures integrating Bayesian updating of model safety factors}, series = {Results in Engineering}, volume = {2022}, journal = {Results in Engineering}, number = {Volume 16, article 100560}, publisher = {Elsevier}, address = {Amsterdam}, doi = {10.1016/j.rineng.2022.100560}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20221028-47294}, pages = {1 -- 1}, abstract = {In the semi-probabilistic approach of structural design, the partial safety factors are defined by considering some degree of uncertainties to actions and resistance, associated with the parameters' stochastic nature. However, uncertainties for individual structures can be better examined by incorporating measurement data provided by sensors from an installed health monitoring scheme. In this context, the current study proposes an approach to revise the partial safety factor for existing structures on the action side, γE by integrating Bayesian model updating. A simple numerical example of a beam-like structure with artificially generated measurement data is used such that the influence of different sensor setups and data uncertainties on revising the safety factors can be investigated. It is revealed that the health monitoring system can reassess the current capacity reserve of the structure by updating the design safety factors, resulting in a better life cycle assessment of structures. The outcome is furthermore verified by analysing a real life small railway steel bridge ensuring the applicability of the proposed method to practical applications.}, subject = {Lebenszyklus}, language = {en} } @phdthesis{Harirchian, author = {Harirchian, Ehsan}, title = {Improved Rapid Assessment of Earthquake Hazard Safety of Existing Buildings Using a Hierarchical Type-2 Fuzzy Logic Model}, doi = {10.25643/bauhaus-universitaet.4396}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20210326-43963}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {143}, abstract = {Although it is impractical to avert subsequent natural disasters, advances in simulation science and seismological studies make it possible to lessen the catastrophic damage. There currently exists in many urban areas a large number of structures, which are prone to damage by earthquakes. These were constructed without the guidance of a national seismic code, either before it existed or before it was enforced. For instance, in Istanbul, Turkey, as a high seismic area, around 90\% of buildings are substandard, which can be generalized into other earthquakeprone regions in Turkey. The reliability of this building stock resulting from earthquake-induced collapse is currently uncertain. Nonetheless, it is also not feasible to perform a detailed seismic vulnerability analysis on each building as a solution to the scenario, as it will be too complicated and expensive. This indicates the necessity of a reliable, rapid, and computationally easy method for seismic vulnerability assessment, commonly known as Rapid Visual Screening (RVS). In RVS methodology, an observational survey of buildings is performed, and according to the data collected during the visual inspection, a structural score is calculated without performing any structural calculations to determine the expected damage of a building and whether the building needs detailed assessment. Although this method might save time and resources due to the subjective/qualitative judgments of experts who performed the inspection, the evaluation process is dominated by vagueness and uncertainties, where the vagueness can be handled adequately through the fuzzy set theory but do not cover all sort of uncertainties due to its crisp membership functions. In this study, a novel method of rapid visual hazard safety assessment of buildings against earthquake is introduced in which an interval type-2 fuzzy logic system (IT2FLS) is used to cover uncertainties. In addition, the proposed method provides the possibility to evaluate the earthquake risk of the building by considering factors related to the building importance and exposure. A smartphone app prototype of the method has been introduced. For validation of the proposed method, two case studies have been selected, and the result of the analysis presents the robust efficiency of the proposed method.}, subject = {Fuzzy-Logik}, language = {en} } @phdthesis{Abbas, author = {Abbas, Tajammal}, title = {Assessment of Numerical Prediction Models for Aeroelastic Instabilities of Bridges}, publisher = {Jonas Verlag}, address = {Weimar}, doi = {10.25643/bauhaus-universitaet.2716}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20180515-27161}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {275}, abstract = {The phenomenon of aerodynamic instability caused by the wind is usually a major design criterion for long-span cable-supported bridges. If the wind speed exceeds the critical flutter speed of the bridge, this constitutes an Ultimate Limit State. The prediction of the flutter boundary, therefore, requires accurate and robust models. The complexity and uncertainty of models for such engineering problems demand strategies for model assessment. This study is an attempt to use the concepts of sensitivity and uncertainty analyses to assess the aeroelastic instability prediction models for long-span bridges. The state-of-the-art theory concerning the determination of the flutter stability limit is presented. Since flutter is a coupling of aerodynamic forcing with a structural dynamics problem, different types and classes of structural and aerodynamic models can be combined to study the interaction. Here, both numerical approaches and analytical models are utilised and coupled in different ways to assess the prediction quality of the coupled model.}, subject = {Br{\"u}cke}, language = {en} }