Static or dynamic characteristics of civil infrastructures may generally differ fromthose of their initial design stage. Especially serviceability and stiffness degradation ofstructures, which are major factors used to verify structural conditions, could beidentified by dynamic characteristics. As one of the most important measures toidentify the dynamic characteristic of structures, displacement responses have beenfrequently measured for civil infrastructures even though they have some difficultiesdepending on the on-site condition of structures. In addition, the contact typedisplacement sensors may require temporary support frames to fix their sensor bodiesor targets. As an alternative to reduce the installation expenses and enhance thereliability of measured data, a noncontact sensing method to measure the displacementresponses in a remote distance without attaching sensors is needed. In this study, amethod to measure multi-point displacement responses by using a digital imageprocessing technique is suggested. Digital images are acquired by a commercial digitalcamcorder, which is the sensor to remotely measure displacement responsesconsidering convenient and economical aspects for use. A digital image correlation(DIC) technique as one of digital image processing techniques is applied to developthe image processing algorithm and an image transform function (ITF) to correct thegeometric distortion induced from the deformed images is used to increase theresolution of displacement responses. And, the shifting of image measurementequipment is also corrected to increase the resolution of displacement responses andmodal frequencies.
展开▼
