Uncertainty of measurement and its influence on essential characteristics of post‐installed fasteners

Abstract

Testing laboratories according to IS0 17025 have to define their uncertainty of measurement in conducting tests. This can be done either by exact calculation or by means of an accurate estimation. All relevant contributions to the measurement uncertainty may be considered in this estimation. For the testing of post‐installed mechanical fasteners in concrete the European Assessment Document EAD 33232 resp. Technical Report TR 048 also demands the fulfilment of the specifications according to ISO 17025 considering the uncertainty of measurement. In this contribution a specific model for testing laboratories in the field of fastenings is provided. Based on the concrete‐cone‐capacity model the contributions of measurement uncertainty for the determination of the failure tension load in concrete are defined. The mathematical derivation of the sensitivity factors for the influence on the measurement uncertainty is shown. By means of a simplified method a proposal for the determination of the measurement uncertainty of tension loads, depending on the uncertainty of the concrete basement and embedment depth, is given.