Damage identification based on dead load redistribution: Effect of measurement error

The effect of measurement error on the results of a new method for damage identification in large, massive civil structures is presented. The damage identification procedure is based on the redistribution of dead load in the structure that takes place when damage occurs. Damage is modeled in the flexural member by a section of reduced flexural rigidity. Static strain measurements are used as input to the procedure. The damage identification parameters are determined using a genetic algorithm. The effect of measurement error is investigated using Monte Carlo simulation. The measurement error is modeled as a Guassian, zero mean random variable. When the model element length is equal to the damage zone length, the results are in good agreement. The correct location and severity is determined even for significant levels of measurement error. The error-to-strain ratio is a convenient parameter for establishing when the error is too significant: results show that for error-to-strain ratios below about 40%, the procedure is able to determine the approximate location and severity of damage accurately. Damage is correctly identified, in an average sense, for the realistic case of when the model element length is not equal to the actual damage zone length. False-positive tests are conducted: the procedure is not prone to incorrectly identify damage when it does not exist, even in the presence of significant measurement error.