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The present paper deals with the application of unified particle swarm optimization (UPSO) technique for solving crack assessment problems in frame like structures. UPSO is a scheme for improving performance of standard particle swarm optimization (SPSO) by harnessing its exploration and exploitation ability simultaneously. The objective function formulated for crack assessment purpose uses the changes in natural frequencies and mode shapes as the damage indicators. The efficiency of present crack assessment algorithm is demonstrated by conducting several studies. First, a numerical study conducted among several PSO variants, such as global best SPSO, local best SPSO, PSO with constriction factor, PSO with time varying acceleration coefficient and UPSO for accessing their performance in solving inverse problem for crack assessment. Secondly, the performance of UPSO based algorithm is validated with experimental results. Finally, numerical studies are conducted to investigate the performance of UPSO based algorithm in crack assessment using noisy modal data. The results of these studies indicate that the developed method is capable for crack detection and quantification with satisfactory precision.

A method is presented to detect and quantify structural damages from changes in modal parameters (such as natural frequencies and mode shapes). An inverse problem is formulated to minimize the objective function, defined in terms of discrepancy between the vibration data identified by modal testing and those computed from analytical model, which then solved to locate and assess the structural damage using continuous ant colony optimization algorithm. The damage is formulated as stiffness reduction factor. The study indicates potentiality of the developed code to solve a wide range of inverse identification problems.