Identifying damage location and severity in a template platform located in Persian Gulf using the Improved modal strain energy

Foroozan platform is one of the most important Iranian offshore facilities lies along the border of Iran and Saudi Arabia. As time passes by, the possibility of presence of some damage in the structural members of this platform increases. As a consequence of these damages, the operation of the platform may be disrupted and if the damage grows, especially in sensitive areas such as deck, joints or splash zone that are prone to failure, cause more damage in the future. This highlights the necessity of structural health monitoring of this platform. One of the most common structural health monitoring techniques is the modal strain energy-based damage index which is known as Stubbs index. In recent years, modifications have been made to original version of this index, one of which is to consider the natural frequencies in determining the location of damage. In this paper, using the improved modal strain energy method and considering the natural frequencies in determining the location of damage, the location and severity of damage in the Foroozan platform have been identified. One of the differences between this study and similar studies is the large number of elements of this real platform. The results showed that the improved method has a higher accuracy in locating the damage than the original method (Stubbs index). Also, single and multiple damages, with low and high intensity, were predicted with appropriate accuracy by this method.