Laser-Based Field Measurement for a Bridge Finite-Element Model Validation

In bridge engineering, laser-based measurement techniques show promise in assisting field tests due to their noncontact features. A case study of using laser-based remote sensing to help collect data during in situ testing for a bridge finite-element (FE) model validation is reported in this paper. The skewed two-span bridge in this study was constructed with nine high performance steel girders in two phases. A three-dimensional (3D) FE model of the bridge superstructure was developed based on the information provided by the design files. Various field tests were performed to validate the model: (1) light detection and ranging (LiDAR) scanning, (2) static truck load tests, and (3) laser Doppler vibrometer testing. The LiDAR scanner collected geometrical information of the actual bridge. It was also used to measure girder deflections during load testing. The fundamental frequency of the bridge vibration was obtained by using a laser Doppler vibrometer (LDV). In situ dynamic and static measurements were compared to the FE model results, thus offering validation of the analytical predictions. Such analysis of the bridge superstructure serves as a baseline for post construction investigations, with important implications especially for the long-term structural health monitoring of the system as a whole.