Experimental demonstration of the AQSSE damage detection technique based on finite-element approach

Abstract

It is well-known that the damage in a structure is a local phenomenon. Based on measured vibration data from sensors, the detection of a structural damage requires the finite-element formulation for the equations of motion, so that a change of any stiffness in a structural element can be identified. However, the finite-element model (FEM) of a complex structure involves a large number of degree-of-freedom (DOFs), which requires a large number of sensors and involves a heavy computational effort for the identification of structural damages. To overcome such a challenge, we propose the application of a reduced-order model in conjunction with a recently proposed damage detection technique, referred to as the adaptive quadratic sum-square error with unknown inputs (AQSSE-UI). Experimental data for the shake table tests of a 1/4-scal 6-story steel frame structure, in which the damages of the joints were simulated by loosening the connection bolts, have been available recently. Based on these experimental data, it is demonstrated that the proposed combination of the reduced-order finite-element model and the adaptive quadratic sum-square error with unknown inputs is quite effective for the damage assessment of joints in the frame structure. The proposed method not only can detect the damage locations but also can quantify the damage severities.