This paper addresses about the condition monitoring and damage detection of structural beams by using model based techniques. In this work, a technique for programmed crack recognition as well as localization is exhibited. The structure is thought to be placed with actuators as well as sensors to vibrate and captures its dynamic reaction, includes impacts of vibration. In vibrational appeal, the information incorporates the modal reactions of the structure actuator previously, also after the crack. In order to locate the structure based damage, an element of the structure is taken for simulation, the damage in the structure is simulated by varying the stiffness of the element accordingly. The severity and location of unknown defects are judged closely using damage index (DI) which is calculated from the Frequency Response Function (FRF) is used to indicate the severity and location of the crack by judging closely by Damage Index (DI). The contrasts between dynamical properties in the damaged and undamaged structures give the estimation of Damage Index (DI). This methodology is applied to simple beam and plate with reduced local stiffness. The potential techniques for practical application condition monitoring problems are discussed. © TJPRC Pvt. Ltd.