Reliability analyses are performed for standard type of transmission towers constructed at 14 sites in the Chugoku district located west part of Japan. In analyses the reliability of tower is calculated under the 50-year extreme wind velocity loading. The calculation results pointed out the inconsistency of reliability level among towers. In this study, it is clarified that the current design code for transmission towers based on the ASDM (Allowable Stress Design Method) does not insure consistent level of reliability. In order to keep the consistent level of reliability of towers in Chugoku district, a LRFD (Load and Resistance Factor Design) format is proposed, and optimal wind load factor and resistance factor are calculated for the target reliability index beta_t=2.5 and 3.0 at the first yield limit state. Using the proposed LRFD format the design of towers is made again, and the reliability analysis is perfomed to check that the consistent level of reliability is kept or not.
展开▼
