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Mathematical Problems in Engineering
Volume 2015, Article ID 485319, 12 pages
Research Article

Effect of Cyclic Loading on the Lateral Behavior of Offshore Monopiles Using the Strain Wedge Model

1Department of Civil Engineering, Hongik University, Sangsu-dong 72-1, Mapo-gu, Seoul 04066, Republic of Korea
2Civil, Environmental, and Construction Engineering Department, University of Central Florida, Orlando, FL 32816, USA

Received 24 April 2015; Revised 28 July 2015; Accepted 13 August 2015

Academic Editor: Alessandro Palmeri

Copyright © 2015 Keunju Kim et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


This paper presents the effect of cyclic loading on the lateral behavior of monopiles in terms of load-displacement curves, deflection curves, and - curves along the pile. A commercial software, Strain Wedge Model (SWM), was employed, simulating a 7.5 m in diameter and 60 m long steel monopile embedded into quartz sands. In order to account for the effect of cyclic loading, accumulated strains were calculated based on the results of drained cyclic triaxial compression tests, and the accumulated strains were combined with static strains representing input strains into the SWM. The input strains were estimated for different numbers of cycles ranging from 1 to 105 and 3 different cyclic lateral loads (25%, 50%, and 75% of static capacity). The lateral displacement at pile head was found to increase with increasing number of cycles and increasing cyclic lateral loads. In order to model these deformations resulting from cyclic loading, the initial stiffness of the - curves has to be significantly reduced.