Changes in the pushover analysis results of offshore jacket platforms due to the incorporation of the aging effect of piles

The pushover analysis of jacket platforms in the past has revealed that most of the collapse failures occur due to the lack of strength of the pile foundation. However, when the jacket platforms which have been collapsed due to extreme conditions were looked into, it was found that most of them had their foundations intact. These contrasting facts can be explained with the help of the phenomenon called 'aging of piles'. Aging effects of piles have been experimentally proven to improve the pile capacity with time, but due to lack of proper understanding and suitable techniques to incorporate them, these aging effects were ignored when the pushover analysis was done. In this study, a simple technique of stepping up of the soil curves in order to accommodate the increase in capacity of pile foundation due to aging is utilised. Three different jacket platforms were employed to study the changes of Reserve Strength Ratio (RSR) after the pushover analysis incorporating aging effect of piles. The incorporation aging effect of piles has created both improvement as well as reduction in RSR of the jacket platforms. The maximum improvement in RSR was found to be about 122 and the maximum reduction in RSR was about 12 . The adequacy of the new pushover analysis results in explaining the actual case scenarios are also discussed. The study has provided a deeper knowledge into the behaviour of aged offshore jacket platforms. © 2006-2016 Asian Research Publishing Network (ARPN).