Testing of lattice towers for Ontario Hydro transmission line refurbishment program

As part of the ongoing transmission-line refurbishment study, three single-circuit, 115 kV, Kingston-type suspension towers on rock-anchor foundations were tested to failure. The types of loads applied to the towers were chosen to represent unbalanced loads due to broken skywire and conductor, heavy-ice, strong-wind and wind-on-ice loads. Selected tower members and foundations were instrumented to measure the member loads, tower deflections, and foundation movement during various stages of testing. The measured values were compared with the corresponding predicted values. The correlation between the predicted and actual tower-failure loads is good. The tower tests confirmed that there is reserve strength available for upgrading the conductor on this line. The measured tower member loads and functions loads correlated fairly satisfactorily with the corresponding calculated values. The rock-anchor foundation did not show any movement at all. The test towers, the tower loading schedule, instrumentation, and tower-testing procedures are described. Measured and predicted failure load are presented. Measured and predicted deflections at selected joints just prior to failure and loads on members just prior to failure are also included