ABSTRACT
A combined loading apparatus was jointly developed by Punrattanasin et al. (2003) at the Tokyo Institute of Technology and the Railway Technical Research Institute of Japan. Three feedback servo motors and three loading jacks were used to apply combined vertical load, horizontal load and bending moment on a model footing in the beam centrifuge. The loading speed can be adjusted flexibly within 1 mm/s. A single-axis servo actuator was developed by Silva & Bolton (2004) at the University of Cambridge, as shown in Figure 1. The design mechanism of this actuator is similar to the one developed by Klotz & Taylor (2001). The selected rolled ball screw was 25 mm in diameter with a 10 mm lead, with lead accuracy of 0.025 mm/300 mm. The maximum allowed axial load on the vertical screw was ± 10,000 N, and the maximum linear vertical speed was 10 mm/s at an in-flight acceleration of up to 100 g.
