Analysis of radio communication towers subjected to wind, ice and seismic loadings

The Missouri Department of Transportation radio communication tower network is currently out of date with respect to current tower building codes. The network was created in the 1950s and 1906s as part of the U.S. military civil defense system. The network was designed using the TIA-222-C (1976) or earlier. Today the current code in practice is the TIA-222-F (1996) code. There is a need to assess the condition of the towers in the network and also to determine if they are up to date with current code. A condition indexing (CI) system is a reliable way to assess this problem. However, an analytical method of determining the input parameters for the CI needs to be determined. Therefore the objective of this research is to develop a systematic evaluation and assessment method that could provide the necessary information for the repair and maintenance of the tower network.; Two towers were selected for this project to act as model towers. One tower is guyed, the Taum Sauk tower, and the other is freestanding, Kansas City tower. Both towers are analyzed using the TIA-222-F for wind and ice loadings. The Taum Sauk tower is then analyzed for seismic loading. Also a parametric study to determine the effects of deterioration of tower components on the tower as a whole is completed on the Taum Sauk tower.; The controlling components of the Kansas city tower were found to be the diagonal bracings. The critical bracings were found to be at 88.9% of their maximum capacity. The maximum capacities of the other components of the tower were found not to exceed 51.1% capacity. Therefore, the tower passes for the current code.; The parametric study was conducted on the Taum Sauk tower under wind, ice and seismic loadings. For the wind and ice analysis it was determined that the bracing on the tower controls the structural integrity of the tower. If the braces are damaged by as little as 10%, the capacity exceeds 100% and the tower fails. When damage is introduced to the guys and the legs, the tower fails at 25% and 42% damage, respectively.; The parametric study completed using seismic loading did not provide information about failure. The results of the parametric study showed the increase or decrease in axial force of the components due to deterioration in one or all of the tower components. It is seen that there is a 0.5 kip increase in axial force in the legs when the guy cables are damaged, and a 0.25 kip increase in the legs when the whole tower is damaged to 50% original cross sections. A 0.15 kip increase in axial force in the guys is seen when the legs are damaged to 50% their original cross sections. Damage to either the tower legs or the guys can cause significant increases in axial forces when subjected to seismic loadings.; In this project the towers were analyzed under wind, ice, and seismic loading and the results indicate that some components of the towers are critical and could control the failure. It is recommended that detailed inspection of the towers' critical components be performed to perform a detailed risk assessment.