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Development of a Structural Model Based on Periodicity of Structure to Model the Behavior and Optimal Design of Telecommunication Stations Exposed to Strong Winds

Moussavi Torshizi, Hossein | 2025

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 58723 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Durali, Mohammad; Khodaygan, Saeed
  7. Abstract:
  8. Lattice towers are abundantly used in telecommunication infrastructure. In recent years, with the development of information technology, the installation of these masts has gained more momentum. Despite the many advantages of periodic truss structures (made by repetition of a specific cell), these structures are sensitive and vulnerable to wind. Telecommunication towers are usually exposed to severe climatic conditions as they are usually installed on elevated places. These structures are usually designed based on engineering charts provided by standard codes or national annexes. Unfortunately, we are still witnessing tower failure or performance drops caused by wind excitations. Many studies have focused on model development aiming to improve these standard codes. Estimation of the tower response to wind excitation has attraced many scientists and engineers. These studies may be devided into three classes; experimental, analytical and numerical. Experimental and numerical studies are advantageous in many cases but these approaches suffer from high computational or economical costs. These shortcommings prevent them to be efficiently used in optimization loops, sensitivity analysis and behavior analysis where the target functions need to be computed several thousand times. This problem comes more into interest in fluid domain calculation or interactive solutions where the results must be validated themselves. In this study homogenization has been used to model the structure which has a tapered geometry in many cases. This tapering angle imposes complexities to the PDE system that has been dealt with for the first time in this study. In this study the Euro standard code for wind actions has been used to model wind and its effect on the structure. A closed-form solution -able to be calculated hundred times within a second- has been obtained afterward. These solutions (estimating static and dynamic response of the tower) have been used as a tool for proceeding analyses. In addition to the finite element method, field measurements performed on a specific telecommunication tower during a storm have been used to validate the model. Then, the obtained analytical solution has been used tens of thousands of times in an optimization loop. The Pareto front with two objectives of mass (related to the total price of the mast) and wind induced vibrations (related to the fatigue life and performance quality of the telecommunications equipment installed on the mast) is drawn. This informative chart provides qualitative and quantitative data on the compromise between these two goals. Also, the effect of geometrical design variables on the objective functions has been evaluated and suggestions have been made for the optimal design of telecommunication towers. Finally, the sensitivity of the objective functions to the deviations in the design parameters has been formulated. The optimization has been repeated by adding robust design objectives and suggestions have been made to increase the robustness of the design to these deviations. The current research has the ability to be used in the process of designing masts to be installed in different places, so that the structure can be sufficiently and optimally strengthened to withstand local winds. It is also possible to use this method in investigation of aeroelastic instabilities or truss structures exposed to other fluid flows, and similar cases
  9. Keywords:
  10. Optimal Design ; Robust Design ; Telecommunication Tower ; Wind Induced Vibrations ; Periodic Structure Homogenization ; Communication Infrastructure

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