Beam-end stiffness identification for a structural health monitoring-oriented finite-element transmission tower model using effective optimization techniques

Abstract

As an important issue for establishing structural health monitoring–oriented finite element models for large steel pylons, identification of beam-end stiffness draws the attention of the engineering circle. Since the methods adopted by other researchers for parameter identification are impracticable, a beam-end stiffness identification method which combines in situ measurements for the structure’s global dynamic properties with effective multi-variable optimization methods is utilized to improve the accuracy of established finite element models. A 131-m-high large transmission tower is employed as a case study to validate the method. In situ measurements for the tower’s global dynamic characteristics are performed, and identifications of Young’s modulus for 20 semi-rigid connections distributed along each of the tower’s four main chords are undertaken utilizing three multi-variable optimization methods, that is, the first-order method, the subproblem approximation method, and the response surface method. Static numerical simulations on two detailed connection models prove that multiple uncertain parameters can be correctly and simultaneously identified when appropriate optimization techniques are chosen. Finally, the influence of beam-end stiffness identification on the structural health monitoring–oriented structural safety assessment is revealed by calculating the wind-induced dynamic structural responses for the single tower and the transmission tower-line system, which indicates that identification of the correct beam-end stiffness and updating the structural health monitoring–oriented finite element model are indispensable procedures for reliable structural health monitoring.