Computational modeling the non-linear behavior of critical members causing progressive collapse in steel lattice towers

Investigations from past earthquakes have revealed that the strong seismic loads and strong wind loads can cause damage and even collapse of the steel lattice transmission towers. The effective use of all emergency equipment and infrastructure in natural disasters relies on the functioning of the electricity and communication lines. For this reason, it is very crucial to reduce the risk of damage on steel lattice towers and to maintain its functionality during and after disasters. This thesis is aimed at investigating the collapse mechanism of steel lattice transmission tower under seismic loads and wind loads, as well as predicting the weak areas of tower. For this purpose, a systematic, accurate and reliable numerical computational model of a 55m high steel lattice tower exposed to seismic and wind loads has been created within the ABAQUS / Explicit software. With the proposed numerical computational model, the critical elements of the steel lattice tower that triggered progressive collapse were accurately and reliably predicted. Under the highest permissible wind loads, very little damage was calculated on the leg members in the panel M of the tower, whereas under seismic loads, severe damage was calculated on all vertical leg elements in the panel M and N of the tower. It was observed that these results obtained from the numerical analysis match with collapse mechanism and weak areas formed by critical elements as a result of observation on damaged and collapsed steel towers in the field. The numerical computational model proposed in this study can be used as a guide during the design of a new tower, or it can be used to accurately predict the structural behavior and critical elements of the existing towers.