Assessment of Masonry Compressive Strength in Existing Structures Using a Bayesian Method

Abstract

In comparison to contemporary masonry structures, the material properties of existing masonry often show very high variability. Furthermore, the limited number of material tests in the assessment of existing structures introduces statistical uncertainties, which have to be adequately considered. The safety formats for the design of new masonry structures may therefore be inappropriate. To fill this gap, a method for determining characteristic values and partial safety factors for the compressive strength of existing masonry is developed. First, testing data regarding unit and mortar strength from the solid clay brick masonry of 72 existing buildings is evaluated in order to model prior distributions for the typical variance of unit and mortar strength. Second, the model for estimating masonry compressive strength based on unit and mortar strength according to Eurocode 6 is analyzed, and the corresponding model uncertainty is quantified. Finally, the proposed method is presented. The influence of prior information is demonstrated, and diagrams are provided, which enable a practice-oriented way of determining characteristic values and partial safety factors for a specific building.