Determining Pull-Out Deformations by Means of an Online Photogrammetry Monitoring System (original) (raw)
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The 22th ISPRS Congress, Melbourne, Australia, August 25 – September 1. International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, vol. XXXIX, part B5, pp. 5-8. , 2012
ABSTRACT: Chemical anchorages are applied in many engineering implementations, particularly strengthening of reinforced concrete structures. During strengthening procedure; chemical anchorages should be tested, since they supply to transfer the load between existing construction elements and newly added elements. Therefore; the study of the quality of chemical anchorages is an important issue in construction materials science. In this context; the most important experiment is to determine the pull-out loads of embedded anchorage reinforcement by applying axial loads. In this study; it is aimed to determine the displacements of steel reinforcements, embedded into concrete by using chemical anchorages, while applying axial pulling loads. In order to determine the displacements and load - deformation graphs; starting conditions and every 10 bar pressure applied conditions of the steel reinforcements were captured by the cameras. The obtained images were evaluated by using photogrammetric software. Based on the photogrammetric post-processing results, the load - deformation graphs were plotted and the loads at loss of adhesion were determined.
Measurement of strain on concrete using an ordinary digital camera
Elsevier, 2018
Two-Dimensional Digital Image Correlation (2D-DIC) technique was applied in this experimental study, to measure the steel-concrete bond strain at concrete surface. The bond strain was caused by tensile force when it was subjected to embed reinforced bar of concrete block in the pullout test. A series of digital images from surface of concrete were taken by a semi-professional digital camera (Nikon D80) during the loading. Acquired images were used as input data for two DIC software to calculate deformation. After verifying the displacement results by measured LVDT results, full-field strain components on concrete were calculated at various levels of forces. The results show the measurement of displacement and strain by this method are acceptable to a great extent.
Digital imaging methods have found a great interest in various engineering fields to study stressdeformation characteristics of materials. Recent enhancements in visual instrumentation with the availability of cost-effective hardware and software products make the digital imaging techniques a viable tool to replace direct strain or displacement measurement methods in engineering applications. In this study, deformation characteristics of bolted steel connections are investigated by calculating in-plane displacement distributions using digital image correlation method (DIC). Validation of the method is presented by comparing the strains measured in standard tension specimens using electrical resistance strain gages and the DIC method. Finite element analysis of the connection specimen is also performed to compare the in-plane displacement distributions calculated from both methods. Results from the validation process indicate that the strains obtained from the DIC method compare well with the results of strain gages. The findings also indicate that the displacement distributions calculated from the finite element method may differ from those of the DIC method in terms of distribution pattern, and the location and magnitude of the extreme values of displacements. It is suggested that the proposed method can be used to determine the in-plane displacement distributions for the bolted connections, hence to evaluate their deformation characteristics under loading.
Journal of the Civil Engineering Forum
The embedment length influences the adhesion between the cast iron material and the concrete. The concrete's compression strength also contributes to an increase in bond strength. Therefore, this research aims to determine the maximum pullout force on each variation of the anchor and the optimal embedment length. A gauge is modeled as a rod-type with a diameter of 16 mm, and the embedment lengths used are 5D, 10D, and 15D, while the compressive strengths include fc’ 20, 30, 40, 50, and 60 MPa. Furthermore, a finite element-based application was utilized with the ANSYS Workbench student version. The result showed that the concrete with strengths of 20, 30, 40, 50, and 60 MPa has maximum pullout forces of 27.011, 53.536, 68.657, 68.970, and 84.407 kN, respectively at an embedment length of 15D. It was observed that the failure pattern obtained starts from the defect in the concrete cone and ends with the breakage of reinforcement or steel failure at each variation of concrete stre...