Defective evaluation of concrete structure with risk-based maintenance

Abstract

Effective maintenance for concrete structures is important and urgent tasks. Maintenance cost depends on its start time. Conventional inspection for structural defects consist of non-destructive tests, e.g. Schmidt hammer test, and destructive tests, e.g. cored samples. Defective degrees are decided by total ratings with the tests, but the tests cannot consider the importance of the structures. A concrete slab in a bridge in an urban area is more important than it in a rural area, because the destruction of the concrete slab in the urban area greatly influences on users. The size and kind of damage on the destruction are different according to the roles of the structures. The risk-based maintenance (RBM) is used for the defective evaluation of the concrete structures. If a disaster occurs, the damage can be kept minimum with the RBM. The risk evaluation is expressed a matrix, in which a vertical axial is likelihood for the destruction and a horizontal one is consequences for the damage. The conventional inspection is used only the likelihood that is classified at four levels, e.g. Safety, usefulness, influences for users and aesthetics are evaluated numerically as the consequences. By using the RBM, the effective maintenance is possible and repair cost is cheaper than with the conventional plans.