Identification of jack-up spudcan fixity by an output-only substructural strategy

Abstract

In jack-up design and site-specific assessment, the inclusion of spudcan fixity is an important but challenging task from the viewpoint of accurately quantifying the soil stiffness for each individual spudcan footing. To this end, a time domain output-only identification strategy is proposed in this paper to identify spudcan fixity parameters from only acceleration signals based on an improved genetic algorithm method. The numerical integration algorithm for the dynamic equation is modified to eliminate the need of measuring input forces, and a substructuring strategy is necessarily incorporated to overcome the otherwise computationally difficult (if not impossible) task. As an illustration example, a real jack-up is studied as a three-dimensional frame model with parameters under different foundational and environmental conditions. The numerical study demonstrates the power of the proposed strategy in accurate and efficient identification of jack-up spudcan fixity using limited response measurements. © 2012 Elsevier Ltd.