STUDY OF STRUCTURAL DAMAGE IDENTIFICATION BASED ON THE PROPORTIONAL FLEXIBILITY MATRIX AND IMPROVED MODAL CURVATURE METHOD

According to the commonly used modal curvature methods that take advantage of the diagonal elements of flexibility matrix to identify the damage in the structural damage identification at present, and based on the proportional flexibility matrix, an improved modal curvature method by using a new index called average flexibility difference is presented to identify the structural damages. Compared with that the existed flexibility modal curvature methods can not judge the damage of the start or end element in the structure, the improved modal curvature method can exactly judge whether the start or end element was damaged including other elements by using the diagonal elements of flexibility matrix. In the method, first of all, the first several order vibration mode and frequency from the structural vibration response are gotten to build the structural proportional flexibility matrix of the undamaged and damaged. Secondly, taking advantage of the diagonal elements of the undamaged proportional flexibility matrix, the average flexibility difference was calculated. Then, a new flexibility matrix was build by combining the average flexibility difference with the damaged proportional flexibility matrix. In the last, taking advantage of the pre-existing modal curvature method by using the diagonal elements of flexibility matrix, the structural damage would be identified. The results of numerical simulation damage identification for a ten layers framework shows that the improved method can fast and easily detect the damage of the start and end element of structures by using the improved modal curvature method. This method also can identify the location of damages and easy be used in the engineering structural damage identifications.