Bootstrap-typed criterion studies of online diagnostic to cracks abnormality of concrete dam

Crack is one of the major manifestations of damages on concrete dam, and studies on the safe-monitoring model of concrete dam cracks have always been a focus in dam safety monitoring field. Currently, the corresponding diagnostic methods and the criteria belong to post hoc test (diagnosis) category. But in practice, it is also concerned in the cracking abnormality diagnosis of concrete dam that whether the cracking abnormality will occur in its current state, and whether the original crack safety monitoring model is still appropriate in its current state. This chapter focuses on reflecting different states of cracks abnormality by studying the structural stability of the linear regression model in concrete dam cracks; the main idea is based on the steady state of the regression coefficients in the model to reflect crack abnormal states. Thus, online diagnostic of the concrete dam cracks abnormality corresponds statistically to the model of structural stability (changeable points) or to the problem of online monitoring sequential detection problem. In this paper, the author does different considerations on the concrete dam cracks transformation characteristic, constructs the appropriate online diagnostic methods and criteria, and takes a project as an example to analyse and to verify its established criteria and methods.