Study of modal behavior of a hinged girder model using scanning laser vibrometer

This paper presents the results of modal testing of a laboratory hinged girder model. The model is a built-up structure with bolted aluminum components, and is 8 ft. in length. This model was built to simulate the dynamic behavior of a single girder of an Armored Vehicle Launched Bridge (AVLB), which is characterized by hinged joints and tapered end sections. The model was tested using shaker excitation and a Scanning Laser Vibrometer (SLV). Several vibration modes were identified and mapped out using the SLV. The results show a complicated dynamic behavior due to the unique e geometric features of the girder model. The modal tests conducted were used to gain an insight into the intricacies involved in testing and developing an inspection procedure for the overall bridge.