Traditional vs FEA Based Analysis/Design of Baseplates for Tall Telecommunication & Transmission Poles

摘要

Various shapes of steel poles are commonly used in the telecommunications and transmission industry for carrying telecommunication equipment to transmit signals for communication equipment or wires and power equipment like transformers etc. for power transmission purposes. These poles vary from 50’ to almost 500’ heights with winds being the governing loads in addition to superimposed equipment loads and snow/ice loads and hence require careful design. The poles vary from being round in geometry to 8/12/16/24/28 sided shapes. With large base diameters and appreciable moments and direct loads, typically the pole baseplates are round, hexagonal or square with/without stiffeners and either rest on the supporting anchor rod base nuts or on grout over the base support, all of which require different analysis/ design procedures. From the literature, one can observe that while baseplate analysis and design for large poles structures has not been amply investigated, limited investigations and testing carried out on base plates designed by various methods and most test results have indicated most procedures to be under designing plates. While AISC and ASCE 48 codes provide limited guidance on design of these various types of pole baseplates, ANSI/EIA/TIA 222F & 222G codes merely refer to AISC for design of these different configurations of baseplates. Many proprietary base plate analysis/design worksheets commercially available produce different results. With the availability of advanced structural analysis techniques like FEA, a comparison is made between the baseplates designed by typical methods using commercially available baseplate worksheets and those designed by using the FEA techniques. The analysis results vary appreciably between the traditional methods and the FEA based method. This paper analyses few pole base plates based on FEA and compares them with the baseplates designed by traditional methods and suggests appropriate improvements in the current design/ analysis procedures so as to reduce the appreciable differences between the both procedures.