Resilient Cities and Structures (Mar 2024)
A robust protocol to compute wind load coefficients of telecommunication towers and antennas using numerical simulation for risk and resilience assessment
Abstract
An accurate estimation of wind loads on telecommunication towers is crucial for design, as well as for performing reliability, resilience, and risk assessments. In particular, drag coefficient and interference factor are the most significant factors for wind load computations. Wind tunnel tests and computational fluid dynamics (CFD) are the most appropriate methods to estimate these parameters. While wind tunnel tests are generally preferred in practice, they require dedicated facilities and personnel, and can be expensive if multiple configurations of tower panels and antennas need to be tested under various wind directions (e.g., fragility curve development for system resilience analysis). This paper provides a simple, robust, and easily accessible CFD protocol with widespread applicability, offering a practical solution in situations where wind tunnel testing is not feasible, such as complex tower configurations or cases where the cost of running experiments for all the tower-antennas configurations is prohibitively high. Different turbulence models, structural and fluid boundary conditions and mesh types are tested to provide a streamlined CFD modeling strategy that shows good convergence and balances accuracy, computational time, and robustness. The protocol is calibrated and validated with experimental studies available in the literature. To demonstrate the capabilities of the protocol, three lattice tower panels and antennas with different configurations are analyzed as examples. The protocol successfully estimates the drag and lateral wind loads and their coefficients under different wind directions. Noticeable differences are observed between the estimated wind loads with this protocol and those computed by a simple linear superposition used in most practical applications, indicating the importance of tower-antenna interaction. Also, as expected, the wind loads recommended by design codes overestimate the simulated results. More importantly, the telecommunication design codes inadequately identify the most favorable wind directions that are associated with the lowest wind loads, while the results of the proposed protocol align with observations from experimental studies. This information may be used to select the tower orientation before construction. The findings of this study are of importance for the telecommunication industry, which seeks reliable results with minimal computational efforts. In addition, it enhances the fragility analysis of telecommunication towers under strong winds, and the portfolio risk and resilience assessment of telecommunication systems.
