The collapses of three transmission towers was caused by intense storm at a local domain.According to the safety accidents

field investigation

material test and finite element simulation and cause analysis of tower collapse are carried out.Analysis shows that heavy tension of collapsed guyed portal tower caused the collapse of three towers of 220 kV transmission line.The main reason of guyed portal tower collapse is design defect of main column base

and stay cable relaxation and bolt looseness are the indirect causes.Combined with engineering practice

corresponding countermeasures are put forward.