Damage quantification of beam structures using deflection influence lines

Influence lines (ILs) have recently been proposed as an emerging index for structural damage localization. This study investigated a novel damage detection and quantification method that is based on deflection ILs (DILs) for beam structures. By reconstructing DIL matrices using a matrix decomposition method, the relationship between structural damage and changes in DILs was revealed. Subsequently, a DIL-based method was proposed to locate and quantify damage in beam structures. Numerical case studies and laboratory experiments were conducted to investigate the effectiveness of the proposed method in different scenarios, namely, single or multiple damages in a one-span simply supported beam and a two-span continuous beam. Satisfactory damage localization and quantification results were achieved even with noise interference in the measurements. The influences of sensor number and locations were also examined in the numerical studies. In general, an increasing number of sensors and short distance from the measurement points to the damage locations benefited the damage detection accuracy. The numerical and experimental results demonstrated that the proposed DIL-based method will be a promising field detection technique for the localization and quantification of damage in bridges.