EXPERIMENTAL-VERIFICATION OF FLEXIBILITY DIFFERENCE METHOD FOR LOCATING DAMAGE IN STRUCTURES

A flexibility difference method for locating damage in structures is p resented. This method is based on the estimation of changes in the fle xibility matrix. First, with the help of an analytical model of beams, it is shown that a clear pattern exists for the changes in the flexib ility matrix produced due to the presence of cracks. Next, the method is applied to several damage cases in three wide-flange steel beams. D amage in the beams is created by cutting through the beam using a saw. Experimental modal analysis techniques are used to estimate the natur al frequencies and mode shapes for both the intact and the damaged bea ms. The measured natural frequencies and mode shapes are then used to estimate the flexibility matrix. Using only the lowest three modes, th e flexibility difference method is successful in locating a 13 mm long saw cut in a 102 mm wide flange. The flexibility difference method is also successful in locating multiple damage locations in the beam. (C ) 1995 Academic Press Limited