Rough set algorithm for crack category determination of reinforced concrete structures

Rough set theory is a new mathematical approach to imprecision, vagueness and uncertainty in data analysis. This paper presents a new approach to rough set theory in determining the category of crack causes for insufficient and imprecise crack characteristics observed in regular inspection of concrete structures. The categories of crack causes are classified into four classes, that is, (1) concrete material, (2) construction work, (3) service and environmental factors, and (4) structure and applied loads. The crack characteristics include time of formation, shape, regularity, cause of concrete deformation, and range. The decision table was constructed considering crack characteristics as condition attributes and the categories of crack causes as decision attributes. A minimal decision algorithm for this decision table was generated on the basis of rough set theory; the algorithm is equivalent to the original decision table, but requires minimum subsets of condition attributes. It turned out in determining the category of crack causes that, “time of formation” had the most important influence among crack characteristics, and “shape” could be omitted with the least influence on diagnosis.