In this thesis, a health monitoring method for bridges using Fiber Bragg Grating (FBG) sensors is presented. The procedure consists of the identification of the strain modes and the assessment of damage locations. At first a numerical simulation study is carried out to investigate the effectiveness of the damage assessment of bridges based on the strain modes. Then an experimental study is carried out on a bridge model with a composite cross section subjected to vehicle loadings. Longitudinal strain is measured along the bridge girder using the FBG sensors. Strain mode shapes are identified from the cross spectral density functions of the measured dynamic strain data for various damage case. To improve the capacity for small damage assessment, further processing of the strain mode shapes are carried out, which consists of determining a cubic polynomial to fit the measured strain mode shape locally at each spatial co-ordinate and evaluating difference function between the cubic and the measured strain mode shape. It has been found that the difference functions provide the better information to identify the location of damage.
