Cyclic loading test of friction-type reinforcing members upgrading wind-resistant performance of transmission towers

Two types of friction-type reinforcing members (FRM) are proposed for the purpose of upgrading wind resistant performance of a transmission tower and verified through cyclic loading tests. First, a suitable installation scheme of the FRM is investigated through numerical analysis. Tower-leg-reinforcing type and brace type installation schemes are examined, and numerical analysis shows that the latter is more effective due to the vertical cantilever type behavior of the transmission tower. Based on this result, two types of the FRMs, dissipating energy in slotted bolted connections, are proposed. The one utilizes the relative displacement between the FRM and the tower leg, and the other utilizes that between the separated angles consisting of the FRM as a slip deformation of the slotted bolted connection. Proposed FRMs are installed on each tower leg of the 1/2 scale substructure models of an actual transmission tower body. From cyclic loading tests, the latter type of the proposed FRMs dissipates energy more effectively and is less sensitive to the work tolerance and initial deformation.