Investigation of transmission line tower failures

This paper presents different types of premature failures observed during full-scale testing of Transmission line towers at Tower Testing and Research Station, Structural Engineering Research Centre, Chennai. Failures that have been observed during testing are studied and the reasons are discussed in detail. The effect of non-triangulated hip bracing pattern and isolated hip bracings connected to elevation redundants in ‘K’ and ‘X’ braced panels, on tower behaviour are studied. The tower members are modeled using beam-column and plate elements. Different types of failures are modeled using finite element software and the analytical results and the test results are compared with various codal provisions. The non-linear finite element analysis program NE-NASTRAN has been used to model the elasto-plastic behaviour of towers. Importance of secondary member design and connection detail in overall performance of the tower was studied. Non-linear finite element analysis is useful in understanding the system behaviour and for prediction of failure pattern and ultimate load. Based on the test results the importance of studying the failures is highlighted. The need for testing of transmission line towers is emphasized.