Collapse analysis of transmission Tower

Abstract

Transmission towers play an important role in the operation of a reliable electrical power system that is considered as a lifeline system. Many studies and recent earthquakes investigations have revealed that, many structures mostly transmission towers performed poorly during wind and earthquake load. Besides many contributing factors for damage, Size, depth of footing and different type’s soil mainly structures on soft soil has also massive effect on structures. In case of transmission towers it should be in a straight line at some fixed distance irrespective of soil at that particular place. It is common practice in many earthquake prone areas around the world to analyse the structure using fixed base analysis. This is mainly due to lack of awareness regarding importance of SSI. In order to understand this phenomenon, a study has been performed to show the difference in response when the structure is on soft soil compare to fixed base. Two case studies have been performed to understand the above phenomenon. A 400 KV transmission tower has been design with proper section. In first case base of transmission tower assumed as fixed base. In second case a proper soil domain with infinite elements has been model using acoustic element which is good for wave propagation. Finally progressive collapse analysis (birth to death analysis) has been performed on both the case studies. Both the case studies reveal that there is great difference in response due to SSI. In second case, it was observed more number of elements is getting failed as compare to first case.