Table 1: Grade index for structural damage state.

Parameter N1 (intact) N2 (minor damage) N3 (moderate damage) N4 (severe damage) Change of deflection (mm) a1-a2 a2-a3 a3-a4 a4-a5 Change of strain (ε) b1-b2 b2-b3 b3-b4 b4-b5 Predict damage values by SVM c1-c2 c2-c3 c3-c4 c4-c5 Modal curvature rate d1-d2 d2-d3 d3-d4 d4-d5