Photogrammetric measurements of RC bridge column deformations

The determination of the location of nonlinear response in structural systems is an important step to predict the performance of the system under different loading conditions. In bridge columns, these nonlinear deformations generally occur over a finite hinge length. A model of hinging behavior in reinforced concrete bridge columns will help guide proportioning, detailing and drift estimates for performance-based design. Data was collected during the NEESR investigation of the seismic performance of four-span large-scale bridge systems at the University of Nevada Reno that details deformations in column hinging regions during response to strong shaking events. A photogrammetry method was applied using a reference grid on the top and bottom column surfaces to record and analyze deformations in the plastic hinging regions. The method of application in this study holds several advantages over traditional sensors including that it is a remote visualization technique, inexpensive and simple to analyze the results. The surface deformations and rotations of a reinforced concrete bridge column under dynamic loading has been examined and compared with the results obtained from traditional instruments. The photogrammetry method performed very well to track the lateral and vertical displacements at the points on the grid surface as well as the deformed shape of the hinging regions, but the results of secondary calculations, such as rotations of the column, had limited success.