Displacement Measurement of Bending Tests Using Digital Image Analysis Method

Abstract

Over the last few years due to sharp increase in experimental investigations in the field of structural engineering, the necessity for reliable and precise deformation measurement is felt more than ever. The most common experimental test in the field of structural engineering is bending test in which beam's deformation is evaluated in order to calculate other structural parameters. One of the most usual techniques for obtaining beam's deformation is utilizing Linear Variable Differential Transformer (LVDT) sensors. However, non-mechanical procedures for displacement measurement have shown much interest between researchers. Photogrammetry, Digital Image Correlation (DIC) method and Particle Image Velocimetry (PIV) are some of the new image-based methods for displacement measurement. Due to the advantages of PIV method in the field of experimental fluid mechanics and Geotechnics, the current study has been focused on the performance of PIV method for displacement measurement of bending test in structural engineering. To reach the aforementioned goal, one steel I-beam was subjected to four-point flexural loading and the load-displacement curve was plotted using PIV method. The experimental results obtained from the PIV method showed excellent agreement with LVDT's data. It is concluded that due to the lower cost and potential of obtaining whole displacement field on common bending tests, PIV method could be widely used as an alternative to conventional measurement techniques in structural engineering. Over the last few years due to extreme increase in experimental investigations in the field of structural engineering, the necessity for accurate deformation measurement is felt more than ever. It is obvious that further calculations could be seriously affected by accuracy of the evaluated displacement fields. Bending test is the most common test in the field of structural engineering in which beam's deformation should be evaluated in order to calculate any other structural parameters. Utilizing Linear Variable Differential Transformer (LVDT) is a primitive technique for obtaining deformation of bending tests. Although there are certain benefits of LVDTs such as high accuracy and simple installation, there are also some disadvantages such as high cost, inability to obtain the whole displacement field and extra charges for data acquisition. Photogrammetry is another technique which is applied to