Calibration of Partial Factors for Temporary Structures

Abstract

The Eurocodes currently do not provide a coherent reliability-based justification for the semi-probabilistic design format of temporary structures. Besides the need for suitable target reliability levels, a coherent definition of partial factors is needed, adjusted according to the chosen target reliability level and the intended reference period considered for the design of the temporary structure. When developing such a partial factor approach, attention should be given to the coherency with current Eurocodes to avoid conceptual discrepancies between the design of long-term and temporary structures. In this contribution a full-probabilistic framework for the structural reliability quantification of temporary structures is developed, based on Latin hypercube sampling. A sensitivity study is performed to detect the most important variables to be considered for the reliability analysis. The framework is subsequently used to determine the inherent reliability levels of scaffolds associated the design guidelines and partial factors according to current standards. Furthermore, recommendations for the target reliability levels for temporary structures are proposed, considering an economic optimization procedure. Finally, adjusted partial factors for temporary structures are derived, enabling a rather simple and straightforward, but objective and coherent safety evaluation of temporary structures by practitioners. Such adjusted partial factors are obtained using two methods: (1) an optimization procedure and (2) the Adjusted Partial Factor Method, which was originally developed for adjusting partial factors for existing structures.