Assessment of the effect of the fluctuating component of wind pressure on a lattice telecommunication tower

Abstract

Abstract. The paper presents a calculation methodology for accounting for the fluctuating component of wind loading in the analysis of a spatial lattice telecommunication tower 50 m high, designed according to a modular concept (2.0 m vertical module) with plan-dimension changes along the height. Unlike the standard approach, where the dynamic coefficient is taken as an input multiplier, a methodology based on the peak response parameter is proposed. In this methodology, the equivalent dynamic coefficient is determined by the criterion of the structure’s peak response (top displacement, base bending moment, or critical axial force), and the distribution of equivalent nodal forces is formed so as to ensure equality of the generalized modal force in the first vibration mode. The matrix form of the equations of motion is given in full as , with derivation of the element stiffness and mass matrices of a spatial truss element and rules for assembling the global matrices. An algorithm is proposed for piecewise formation of the equivalent wind load over the height intervals 0–32, 32–34, 34–44, 44–46, and 46–50 m, converting pressure to forces through the effective projected area of the lattice. The methodology provides a physically justified consideration of the fluctuating component without direct time-history simulation of the wind process and improves the reproducibility of calculation results. In addition, the choice of the first mode as dominant for the along-wind response is substantiated, and procedural checks of load consistency are provided through equality of the generalized modal force. It is shown that the piecewise discretization enables correct consideration of structural transitions and differences in «wind-exposed area» along the height, while the use of the effective projected area reduces subjectivity when modeling permeable lattice systems. A control criterion is proposed: and , which guarantees convergence with respect to the selected response quantity.