Implementation of Evaluating Bridge Behavior Using Ultra-High-Resolution Next-Generation Digital Image Correlation (DIC): Applications in Bridge Inspection and Damage Assessment, Final Report [Project Title from Cover]

5-6950-01The Civil Infrastructure Vision (CIV) system is an integrated software/hardware system is based on principles of Digital Image Correlation (DIC) developed at UTSA for TxDOT. The system can be used to monitor surface deformations on bridges to accuracies on the order of 1/1,000th in. Project objectives included training DOT on using the system during load testing and processing the resulting deformation data. Ten bridges were load tested over a period of one year using CIV. Throughout this project, procedural improvements were made to accelerate load testing and minimize traffic disruptions. In the end, the team was able to complete the full process, from arriving to a site through finishing repacking equipment, in less than two hours. This allowed up to three load tests in one day; a much faster process than using traditional instruments, with which a load test could take several days and require direct access to a bridge underside

Size effect on shear strength of reinforced concrete beams

Given the great discord concerning the mechanisms that govern shear failure, the shear behaviour of concrete beam elements with no transverse reinforcement is investigated. The variables introduced in the experimental program are member depth, amount of longitudinal steel reinforcement and concrete strength. The effects of these variables on the shear stress at failure of the concrete are investigated. Two geometrically similar series of beams of different concrete strengths are compared. Beam heights in each of the series range from 90 mm to 960 mm and all the beams have a constant a/d ratio of 2.5.Results show a strong "size-effect" in the behaviour of concrete beam or one-way slab elements subjected to shear, where deeper members have smaller shear stresses at failure than shallower ones. Increasing the amount of flexural reinforcement increases the shear stress at failure while increasing the concrete compressive strength has little or no effect on the diagonal shear resistance of concrete.The ACI Code equations for shear are found to be unconservative for large elements while the CSA Standard simplified shear design method yields conservative predictions within the range of beams tested. For the beams tested, with an a/d ratio of 2.5, the combination of the modified compression field theory and a strut-and-tie analysis provides more accurate predictions