Longitudinal Dynamic Loading of a Steel Pole Transmission Line

Model test results have demonstrated that it is possible to simulate a number of dynamic loading conditions on a scale model of an actual transmission line system, taking into account a large number of variables, and producing results having direct interpretation at full scale. The method appears to be particularly useful in identifying any potential ``trouble areas´´ in an existing design such as the use of horizontal struts on light angle structures, and/or adequacy of fatigue strength under galloping conditions. A sample of the principal findings of this investigation are as follows: 1) A method for rapidly calculating the flexibility (stiffness) of steel pole transmission structures has been developed. The method relies on computer print-out data supplied by pole manufacturers at the time of bid evaluation. 2) Results of broken static wire tests show that structure flexibility reduces both the dynamic load and the residual load below the load calculated for a rigid structure. 3) The maximum loads occur for broken static wire on the most flexible structure, and for ice unload of static wire on the stiffest structure. The latter result is subject to the further restraint of a horizontal strut at a light angle. 4) Unexpectedly high loads were found on the stiffer structure with long insulators (including the horizontal strut) for galloping conductor and galloping static wire tests.