Direct laser dynamic displacement measurement of structural response during testing

Abstract

The paper presents part of the conducted research on laser-displacement sensors for the measurement of structural response in civil engineering applications. Usually, the level of displacement in laboratory or on-site testing is in small to mid-range levels of 1.00 to 25.00 mm and in the frequency range of up to 100 Hz. Appropriate sensors were selected and used according to performance in the sense of resolution/accuracy. Experiments are conducted on steel model beam in the laboratory and on-site real bridge structure. In both analysed cases, data analysis was carried out in the sense of modal frequencies and damping estimation with comparison with numerically computed values. Presented are the results of two experiments, a laboratory-tested model of steel beam and an onsite tested real bridge structure. In both cases have achieved good argument of test results, estimated modal frequencies and damping of tested model/structure. Data analyses conducted used a developed MATLAB script, while the numerical computation conducted used SAP2000_v14 FEM package for structural analysis. Excellent agreement of extracted results was achieved in the case of the laboratory-tested structural model, as well as of extracted results of on-site tested real-world structure in the sense of extracted modal frequencies and modal damping. Finally, the conclusion is that laser-displacement sensors are quite appropriate for small to midrange of expected displacement and are quite appropriate for such applications according to the possibility of installation so that such sensors could be applied for structural testing, particularly for dynamic testing of such structures because of their possibility of high sampling frequency and high resolution/accuracy.