Material strength safety factors for the seismic safety assessment of existing RC buildings

• Safety factors are proposed to characterize material strength in existing buildings.
• The uncertainty due to the number of tests and strength variability are considered.
• The safety factors are compatible with EC8/3 seismic safety assessment methods.
• Safety factors and survey plans are defined for concrete compressive strength.
• Safety factors and survey plans are defined for reinforcing steel yield strength.

New material safety factors (CFmat) are proposed to characterize material strength in existing buildings. These safety factors are developed in order to be compatible with seismic safety assessment procedures defined by current standards such as Eurocode 8 Part 3. The general theory behind the development of the CFmat safety factors considers the uncertainty associated to the number of surveyed structural elements and the inherent variability of the material strength under analysis. The CFmat safety factors are developed using a finite population approach where the material properties in a building are discretized by considering one value per element. The proposed theory is used to define specific CFmat values and survey plans for the concrete compressive strength and for the reinforcing steel yield strength.