Tower Structures for overhead transmission are being used as the main mean of supplying electricity to the country, and many more are expected to be built in the future. However, the domestic overhead transmission tower design standards apply follows ASD (Alloable Stress Design), which does not take into account uncertainty. Therefore, it is necessary to convert it to LRFD (Load Resistance Factored Design), which enables safe and efficient design based on reliability theory. In this study, the LRFD steel structure joint design standard provided in AISC 360-22 and AISC Design Guide 24 for overhead transmission and transmission. Appropriateness of design application was reviewed. The adequacy review was conducted by comparing the change in the strength trend and failure mode of the nominal strength equation and the finite element analysis for each parameter.
For the joint to be studied, circular hollow steel splice, and circular hollow steel K-joint were selected considering joint’s shape and failure mode. The study parameters were selected for members that do not affect the strength of the entire tower structure, and parameters were adjusted within the limits of the minimum distance between bolts, edge distance, and end distance. The analysis results are as follows.
(1) As a result of the analysis of the round steel pipe splice, it was confirmed that the faliure mode and strength tendency according to the parameters were consistent between the nominal strength equation and the finite element analysis.
When the flange thickness is thinner or the bolt center-pipe wall distance is longer, it was observed that the tensile load on the bolt was generated more than the proof-stress due to the prying action. However, in the tensile strength equation of bolts considering the Prying action, the flange thickness was not included in nominal equation.
(2) K-joint of circular hollow steel showed different strength trends and failure modes in the nominal strength equation and finite element analysis results. In the reinforced K-joint, stress was concentrated at the lower part due to the increase in stiffness of the joint. Therefore, for all analysis models, local buckling showed a constant failure mode and a small change in strength. However, the failure mode of the unreinforced K-joint changed from gross area yielding to local buckling as the strength increased, and the strength trend also showed a difference from the nominal strength equation. Through this, it was concluded that it is necessary to develop a strength equation that reflects the combination of the load of the main member and the load of the dead material in the design equation of the K-joint.