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Modern offshore jacket structures are designed with piles that are carrying variable axial loads, large shear forces and bending moments. Even if the geometry of the grouted connection is quite simple the load transfer mechanism is complex. It involves friction, contact stresses, brittle material, abrasion, cyclic degradation, etc. Current design recommendations were developed based on relatively small scale test and with only a few tests performed with cyclic loads that include change of load direction. In order to study the capacity of grouted connections with shear keys for alternating axial load, four (4) segment specimens were tested. The specimens were full scale representation of a segment of a part of the annulus of an axially loaded pile sleeve connection. The load-carrying axial capacity under cyclic loading was found. [ABSTRACT FROM AUTHOR]

In this paper the tower base shear forces and bending moments of a shallow water offshore wind turbine have been rigorously calculated by using a nonlinear simulation method taking into account the bottom effects. It has been found that nonlinearly simulated realistic waves with bottom effects should be used as inputs in the stochastic time domain simulation in order to design an un-conservative support structure for the offshore wind turbine. In order to further improve the simulation efficiency, a transformed linear simulation method has been utilized in this paper for generating equivalent waves as those obtained from the nonlinear simulation method. The accuracy and efficiency of the transformed linear simulation method have been convincingly substantiated through the subsequent calculation examples in this article. • The loads and responses of a wind turbine are rigorously calculated. • Nonlinearly simulated waves with bottom effects are used. • A transformed linear simulation method is utilized. • The transformed linear simulation method can offer more accurate predictions of the loads and responses. • The transformed linear simulation method has a higher efficiency in comparison to an existing method. [ABSTRACT FROM AUTHOR]

To increase the horizontal and uplift resistances of piles in offshore structures, pile reinforcements such as anchored piles, batter piles, and micro piles have been generally applied. In this study, the emphasis was on quantifying the reinforcement effect of an anchored pile on the horizontal and uplift resistances of a submerged breakwater. A framework for determining the seabed soil spring constants (p-y curve and t-z curve) is proposed from an analytical method and numerical analysis. Based on the results, a new hyperbolic load transfer curve is proposed to design anchored piles by considering the reinforcement effect, which considers the reinforcement coefficients of horizontal and uplift loads obtained from the load transfer curves. The proposed load transfer curves are compared against the results from the full modeling analysis and show good agreement. Through comparisons with case studies, it is found that the effects of the shear force, bending moment, and displacement are more significant for anchored piles than for unreinforced piles. Thus, the proposed curves appropriately represent the reinforcement effect of anchored piles in offshore structures. • Load transfer curve for anchored piles considering reinforcement effect is proposed. • Numerical analyses are performed for reinforcement effect for anchored piles. • Proposed curves considers the reinforcement coefficients of horizontal and uplift loads. • Proposed curves appropriately represent the reinforcement effect for offshore structure. [ABSTRACT FROM AUTHOR]