Real-Time Substructure Testing Method And Its Application

Modern structures become larger and more complex than before. In order to improve the seismic performance of these structures, new concepts of structural design, new structure forms and new structural material have been emerging for decades. Modern structural aseismic techniques, especially the structural control techniques, bring new challenge to the traditional seismic test methods. The real-time loading rate is desired for the tests of structures which include highly rate-dependant components; the structural tests with full or large scale are desired for the large and complex structures, because the similitude relation of the over-reduced scale specimen and full scale structure is too difficult to be strictly satisfied. Real-time substructure testing (RSTing) is a new method which seeks to resolve these problems by performing tests on key elements of the structure at full or large scale, with the physical test coupled in real time to a numerical model of the surrounding structure. RSTing shows great potentials on revealing the dynamic behaviors of structures more accurately and economically.The basic methods of RST and its application are studied in this thesis, the main work and results are as following:1. The implementation method of RSTs based on the MTS system is presented. With the calculation function of FlexTest GT controller and proper configuration of MTS system, the physical test coupled to a numerical model in real time is realized. The RSTs are carried out to verify the performance of MTS system. The experimental results agree well with the calculated ones, which show that the MTS system satisfies the requirement of RSTs.2. The effect of actuator delay and compensation is numerically investigated taking into account the influence of actuator dynamics on the numerical property of time stepping integration methods. Two simplified actuator models, including the bilinear step response model and the second order transfer function model, are introduced; the effect of time delay and compensation methods are investigated; the delay compensation method based on the simplified actuator models is introduced. The analysis and test results show that the two simplified actuator models describe the dynamics of actuator well; the stability of the operator-splitting method is worsening in the presence of actuator delay, and can be improved by a third order compensation method. The delay compensation method based on the actuator dynamics can effectively compensate the actuator delay.3. To avoid the iteration process in RSTs using an implicit time integration method, the equivalent force control (EFC) method is developed. In the case of damper specimen, the linear force interpolation method is introduced to guarantee smooth velocity response of the experimental substructure, the influence of which on the numerical aspect of time stepping integration method is explored. The proportional-derivative controller is adopted to demonstrate the design of the equivalent force controller. The analysis and experimental studies show that RSTs with the EFC method will attain satisfactory test results if the controller is designed properly.4. The RSTs for JZ20-2NW offshore platform with MR damper is performed. The stability and accuracy of RSTs with MTS system and structural dynamics are analyzed, and then the RSTs are carried out to evaluate the performance of the offshore platform with MR damper under the excitation of ice force and earthquake. The analysis and tests results show that the MTS testing system satisfies the stability and accuracy requirement of RSTs of JZ20-2NW offshore platform. The tests results also show that the MR dampers can effectively control the earthquake and ice induced vibration of the offshore platform.