Reliability Assessment of Steel Lattice Tower Subjected to Random Wind Load by the Stochastic Finite-Element Method

Abstract

This work concerns the stochastic finite-element method (SFEM) reliability analysis of a skeletal, very slender steel telecommunication tower calibrated with a full-scale pushover experiment carried out for the same tower. The basic SFEM implementation is completed with common application of the generalized stochastic perturbation technique (SPT) and of the response function method with polynomial basis of the statistically optimized order. Verification of the proposed stochastic technique is carried out for the first four probabilistic moments by a comparison with traditional crude Monte Carlo simulation and, alternatively, with semianalytical methodology using the same polynomial structural responses as SPT and the well-known probabilistic integral definitions. Characteristic mean wind speed is introduced here as the input random Gaussian variable, while the computational model is subjected to the wind profile linearly dependent upon this mean speed consistent with applicable European design codes. The SFEM analysis is carried out here including large deformations of the tower elements and dynamic excitations in each node induced by the given trial wind spectrum. Finally, second-order reliability method (SORM) analysis is provided on the basis of the resulting extreme normal forces in the tower legs and their counterparts taken directly from the full-scale pushover experiments. The obtained results show that reliability indices for these towers according to the engineering codes have larger magnitudes than these corresponding to the experimental statistics and SFEM.