Base excitation and load identification based on Craig reduction model

Load identification use measured acceleration of few degree of freedom (DOF) to determine external applied load. Base excitation give movement upon foundation freedom to excite the structure, and then obtain the whole dynamic response. Making use of characteristics of Craig reduction model, and the known motion of interface DOF, the dynamic response of all other DOF could be calculated, thus the base excitation was achieved. The load identification could be performed through the dynamic equation with these motion of interface DOF and the calculated dynamic response of non-interface DOF. The only error of this method for base excitation and load identification is the difference between the Craig reduction model and the original finite-element model. For this reason, frequency response analysis was applied to determine the precision of Craig reduction model through the variation of the frequency response curve. An example was given to demonstrate the validity of the present base excitation and load identification method.