Sensitivity of self-elevating unit leg strength to different chord space

Abstract

Aiming to optimize the truss leg structure of self-elevating unit, the sensitivity of leg strength to different chord space was analyzed, and the optimal value of chord space for legs was presented. The wind load under storm condition was obtained by wind tunnel test, and the wave and current loads were calculated based on theoretical and numerical methods. The natural vibration period and first order offset value were obtained by eigenvalue analysis, thus the inertial load considering the dynamic amplification factor and the inertial moment considering the geometric nonlinearity were obtained. It is found out through analysis that: the inertial load considering the dynamic amplification factor is more sensitive to chord space under a certain wave and current angle, and decreases with the increase of chord space in general; the inertial moment considering the geometric nonlinearity also decreases with the increase of chord space. According to the environment load, the strength of leg structures at different chord spaces were checked and the sensitivity of the structure strength to chord space was compared. Based on this, the optimal values of chord space for legs at three water depths were presented. Key words: self-elevating unit, environment load, leg strength, chord space