A Stereovision Deformation Measurement System for Transfer Length Estimates in Prestressed Concrete

This work proposes a novel, stereo-vision based test setup for the accurate measurement of relatively small surface strain fields that develop in prestressed concrete prismatic beams after strand release, with the goal of providing an effective and accurate alternative to existing measurement techniques. To this end, the enclosed paper discusses the proposed StereoDIC system configuration, introduces the technique for acquiring full-field shape, deformation and strain measurements using 3D Digital Image Correlation (StereoDIC), verifies the proposed technique through high fidelity laboratory and computer simulations and proposes a computational algorithm that automates the calculation of the transfer length using these measurements. Our studies show that the proposed approach is an effective and accurate non-contacting technique for determining the small surface strain fields in full-scale, prestressed concrete beam specimens, providing essential data to reliably estimate the transfer length in prestressed concrete beams. Though implementation of the procedure in industrial scale facilities is beyond the scope of this paper, discussion regarding this extension is provided.