Reliability-based structural analysis of a bucket wheel excavator's load-bearing steel structure

Structural analysis of large structures such as bucket wheel excavators (BWE) are generally performed using the finite element analysis and assessed according to the portion of the material's yielding limit. Consequently, a structure is evaluated just by the maximum stress at the specific location. In order to address the whole structural response of the object, this paper introduces a reliability-based structural evaluation presented on a case study of the BWE SchRs 630. Although the BWE reliability has been explored in literature, most of the research was based on data obtained from failure of systems and structure, over the years. Nevertheless, this investigation is dividing the pure structural from the system failure by mapping and analyzing the specific structural zones of the BWE. Finite element method obtained randomized stresses (i.e., D – demand of the structure) in a structure are categorized as independent variables and modeled using probability density function. The same is performed in case of the criterion – yield strength of the structure's material (i.e., C – capacity of the structure). Furthermore, yield strength distribution itself is evaluated according to the industry's practice meaning that mean value of the yield stress is to be reduced when used as a criterion for the stress assessments. Therefore, a margin function is analyzed according to the equation: M = C – D. Consequently, the structure is assessed as a whole through the introduction of the reliability index based on stresses. Such evaluation could enable comparison between the corresponding and similar structures in terms their structural response in more holistic manner