Beam moment and shear force calculations using digital-camera experiments

This article presents an image-based method to find the beam moment and shear force using the measured beam displacements. A least-squares method is first developed to find the rotations and lateral displacements at beam ends using the measured displacements along the beam. Then, the moments and shear forces of this beam segment are obtained using the matrix formulation including shear deformation and large displacement effects. Two experimental schemes, image symbol dot and image-correlation methods, were used to validate the accuracy of the proposed scheme. The comparison of the results between the finite element analysis and the two methods shows acceptable accuracy. Although this method is mainly applied to the elastic region, one can still find the moment and shear force at the inelastic region using the equilibrium equation.