In this test, RIEGL LMS-Q120 2D laser scanner [17] is fixed at the ground to obtain
two-dimensional coordinate data of every floor level. The scanner has a divergence of 2.7 mrad
corresponding to 27 cm increment of beam width per 100 m of range. During the measurement, the
scan angle range was set to be 80°and 200 data points were obtained per each scan. It was assumed
that there is no relative lateral displacement among data points in the slab at the same floor. With the
initial displacement of 50 mm at the top of the test model, the free vibration responses of the test
model measured from both laser displacement sensors and 2D laser scanner are compared in Figure 6.