DAMAGE DIAGNOSIS OF TRUSS STRUCTURES BY ESTIMATION OF FLEXIBILITY CHANGE

A new method for damage diagnosis of truss structures is developed. Th e method is based on estimation of change in the flexibility matrix. T he flexibility matrix is estimated from natural frequencies and mode s hapes of the structures. This method is capable of determining both lo cation and amount of damage in structures. Unlike techniques based on stiffness matrix, this method requires measurement of only a few of th e lower frequency modes. Moreover, this method does not require a prio r development of a calibrated finite element analysis model of the str ucture being tested. If a finite element analysis model is available, this method can take advantage of it and perform damage diagnosis usin g even fewer modes. The developed method is first illustrated using a four degree-of-freedom spring mass system. Feasibility of the method i s numerically demonstrated using a one-bay six-bar truss and a ten-bay fifty-one-bar truss.