The European collaborative programme on evaluating the performance of shaking tables

This paper describes a concerted performance appraisal of four of Europe's large shaking tables. Three of the shaking tables were capable of controlled motion in all six degrees of freedom, while the fourth was constrained to move in the three translational axes only. The principal study was the fidelity of the input motion at the testpiece. At all four tables this was found to be satisfactory, but, in one case, the time taken for the tuning process was often more than one hour, and in all cases highly trained and experienced operators were required. Even so, the tuning process was 'out of real time', which required that the physical properties of the testpiece should not change during the tuning process. This meant that controlled nonlinear specimen behaviour could not be studied experimentally. This was a major drawback, since modern economic design requires use of nonlinear material properties, leading to progressive failure of redundant members, but not total collapse. The studies did, however, have a major beneficial effect in showing that existing control systems were out of date. Further research programmes were therefore started which have already had the major consequence of producing 'real-time' control of shaking tables.