Browsing by Author "Mwanangombe, Judah"

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    Failure mode dependence of target reliability in concrete and steel structures in ultimate and serviceability limit states
    (Stellenbosch : Stellenbosch University, 2023-02) Mwanangombe, Judah; De Koker, Nico; Way, Andrew; Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering.
    ENGLISH ABSTRACT: Optimal cost of structures is a very expansive topic in structural design. Among the many key factors that affect its outcome is the decision parameter of a limit state in focus. There is an intrinsic effect on the target reliability as the decision parameter is changed. Rather than designing for every limit state using a case-specific formulation of reliability design, structures are often designed using a generic approach simulated in the partial factor methods of design. Van Nierop (2018), inferred that there is a discrepancy in the target reliability obtained using a generic formulation as compared to when a case-specific limit state is used for SLS limit states. This research is motivated by the desire to investigate the efficiency of the decision parameter in ULS and SLS limit states in predicting the target reliability of concrete and steel structural members. Notions of structural reliability design are employed. Specific limit states in structural concrete and steel members specifically: flexure, shear, tension, lateral torsion buckling, compression, deflection and crack width were considered individually.Risk-optimal target reliability of each specific limit state was compared to that yielded by a generic approach, and the degree of loss in optimality assessed. It is shown that the form of the decision parameter is responsible for how efficient it is in predicting target reliability. SLS limit states in concrete and steel indicate case-specific decision parameters more efficient than obtained using the generic formulation. For ULS, flexure in concrete, shear in concrete, tension of steel members, compression of steel short columns all yield case-specific decision parameters that are as efficient as those of the generic simulation of each case-specific limit state. However, for ULS, flexure of steel section members, lateral torsional buckling of steel section members and shear of steel section members have significant discrepancy in the target reliability obtained from cost optimisation using case-specific formulation and generic formulation. It is inferred that the case-specific decision parameter is more efficient than the generic decision parameter.