Numerical and experimental study to identify the location and severity of damage at the pier using the improved modal strain energy method-Case study: Pars Asaluyeh LPG export pier

Deck-pile pier structural system is one of the most common types of pier construction systems. Corrosion, ship collisions and huge storms cause general and extreme damages, especially in the deck and the splash zone of the wharf. If the location and severity of the damage is known at the early stages of the damage, they can be repaired as soon as possible. One of the available methods for identifying damage in structures, which is based on the changes in the dynamic properties of the structure, is the modal strain energy method. In recent years, modifications have been made to the original version of this method, the Stubbs index, one of which is the consideration of natural frequencies in locating the damage, known as the improved modal strain energy method. In the present study, using both Stubbs index method and improved method, an experimental and numerical study is performed to identify the location and determine the severity of damage in the members located in the deck and splash zone in a real LPG export deck- pile pier (pier number Fourteen) located in the port of Pars-Assaluyeh, in Persian Gulf. The results showed that the improved method has higher accuracy in locating the damage than the Stubbs index method. Also, single and multiple damage, with low and high severity, were predicted with appropriate accuracy by this method.