Study of load combination values for existing frame structures

Abstract

A great number of structures dating back several centuries have been preserved on the basis of their historical and economic importance. In terms of the actual condition of these structures, it is necessary to analyse and assess their structural performance. Although there are differences between the design of new structures and the assessment of existing structures, the design expression of the ultimate limit state (ULS) and corresponding partial factors are currently used to evaluate the reliability of existing structures. Based on the design expression of the ULS and probabilistic approaches to consider the structural resistances and loads of existing structures, load combination values (LCVs) of existing frame structures under different target periods of usage (TPUs) were ascertained. These acquired values can be applied to the safety analysis of existing structures. To determine the LCVs, optimised analyses of 14 representative structural components taking into account different loading ratios under four load combinations were performed. The results show that different TPUs for existing structures lead to lower or higher LCVs compared with the initial design phase. Therefore, different TPUs should be considered during the assessment of existing structures.