STRUCTURAL HEALTH MONITORING OF RCC STRUCTURE USING NDT UNDER DIFFERENT EXPOSURE CONDITION – A CASE STUDY

Abstract

This review paper analyzes why and how nondestructive testing (NDT) measurements can be used in order
toassess on site strength of concrete. It is based on (a) an in-depth critical review of existing models; (b) an analysis of
experimental data gathered by many authors in laboratory studies as well as on site, (c) the development and analysis of
synthetic simulations designed in order to reproduce the main patterns exhibited with real data while better controlling
influencing parameters. The key factors influencing the quality of strength estimate are identified. Two NDT techniques (UPV
and rebound) are prioritized and many empirical strength-NDT models are analyzed. It is shown that the measurement error
has a much larger influence on the quality of estimate than the model error. It is based on the use of a prior double power
law model, with only one parameter to identify. The analysis of real datasets from laboratorystudies and from real size
buildings show that one can reach a root mean square error (RMSE) on strength of about 4 MPa. Synthetic simulations are
developed in order to better understand the role played by the strength range and the measurement error. They show that the
number of calibration cores can be significantly reduced without deteriorating the quality of assessment. It is also shown that
the optimal calibration approach depends on the number of cores.