Investigations of a practical wind-induced fatigue calculation based on nonlinear time domain dynamic analysis and a full wind-directional scatter diagram

Abstract

To cite this article: Junbo Jia (2014) Investigations of a practical wind-induced fatigue calculation based on nonlinear time domain dynamic analysis and a full wind-directional scatter diagram, Ships and Offshore Structures, 9:3, 272-296, DOI: 10.1080/17445302.2013 Ships and Offshore Structures, 2014 Vol. 9, No. 3, 272-296, http://dx.doi.org/10.1080/17445302.2013 Investigations By performing the nonlinear time domain dynamic analysis, and calculating the wind-induced fatigue using the procedure presented by this author, this paper investigates the influences from different drag coefficient specification systems. The study shows that the drag coefficient specified by Norsok is more conservative than that of the DnV system, mainly due to Norsok's rough categories of the drag coefficient values varying with the Reynolds number. Furthermore, the effects of time increment step length, time duration for simulation as well as the flexibility of wind strut-main flare boom connections are also investigated. By comparing the fatigue life from dynamic analysis with its static counterpart (without taking into account the inertia effects of the structural and non-structural installations), the significance of the contribution from the structure's dynamic response can be identified. It is suggested that the modelling of secondary structures such as a flare and vent line must be carefully considered, as this may significantly influence fatigue damage calculation. In addition, the effects of gravity on the structure's fatigue damage are also studied and the conclusion challenges traditional engineering practice.Finally, non-Gaussian responses are discussed through the statistical investigation of the local responses. The wind fatigue calculation procedure presented can be widely adopted for the similar study on high-rise tubular structures.

Wind-Induced Fatigue Analysis of High-Rise Steel Structures Using Equivalent Structural Stress Method

“…For example, Repetto [2][3][4] selected several types of mast structures, including telegraph poles and lamp-posts, and, by considering the changing wind speed and wind direction simultaneously, performed fatigue assessment of along-wind and crosswind response effect on structures from the frequency domain and time domain, respectively. Jia [5,6] presented a practical and efficient approach for calculating wind-induced fatigue of tubular structures and studied the effects of the wind direction and wind grid size on the high cycle fatigue of the structure. However, the fatigue assessment of welded joints based on nominal stress and hot spot stress methods cannot accurately consider the effect of the notch effect, which is a strong stress concentration near notch roots or notch toes.…”

Numerical Simulation of Fluctuating Wind Effects on an Offshore Deck Structure

“…Many accidents involving deck components such as a derrick and crane due to the random wind loads have already been reported in damage investigation [3]. However, practical estimation and assessment of the fluctuating wind and wind-induced dynamic response of the complex offshore deck structures are still involved problems [4]. Therefore, with the development of the oil exploitation to deep sea, it is necessary and important to carry out the wind field analyses of offshore structures to guarantee a reasonable safety design.…”