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This paper presents a cyclic equivalent spring (p-y) model describing lateral soil resistance on offshore well conductors and piles in normally to lightly overconsolidated clays subjected to fatigue cyclic motions. Improved understanding and characterization of cyclic lateral soil response is critical in fatigue assessment of well conductors and piles subjected to dynamic fatigue loads. Key features of the model include nonlinear load-displacement behavior with stiffness degradation during cyclic loading. The model provides a full description of soil resistance during lateral loading, including an initial short-excursion monotonic loading stage, a transient stage of progressive degradation in stiffness from the first excursion, and a steady-state stage involving minimal changes in soil stiffness after a large number of load cycles. The model input parameters obtained from back-analysis of data derived from centrifuge tests on model conductors subjected to harmonic lateral loads are presented in this paper. This model has capabilities of simulating random load sequences. Fatigue damage in well conductors and piles arises from changes in axial and bending stresses, with the latter being more dependent on lateral soil response. Accordingly, the proposed model is evaluated primarily in terms of its ability to accurately predict bending moments when the spring model is used in conjunction with a laterally loaded soil-structure interaction model. The model successfully predicts the maximum change in cyclic bending moment (change in moment during a load reversal) and the location of the maximum cyclic moment along the conductor depth approximately within a 20% range. This performance evaluation was derived by comparing the model computations/predictions to the test data from the centrifuge program and validated within the tests displacement range of 0.1D. The current form of the model does not consider consolidation effects, which may significantly affect long-term loading predictions used in fatigue life assessments. [ABSTRACT FROM AUTHOR]

This work studied the coupled stretching and bending deformations of a through-thickness nonelliptical elastic inhomogeneity embedded in an infinite matrix within the context of Kirchhoff isotropic and laminated plate theory. The matrix was subjected to uniform remote membrane stress resultants and bending moments, and was also subjected to a concentrated rotational moment at any position. Our analysis, based on complex variable methods, indicated that when the nonelliptical shape of the inhomogeneity is suitably designed and when three specific conditions on the remote loading are met for a given set of material and geometric parameters characterizing the composite: (1) the elastic inhomogneity is harmonic, (2) the internal stress resultants inside the inhomogeneity are uniform and hydrostatic, and (3) the hoop membrane stress resultant and hoop bending moment on the matrix side are uniform along the inhomogeneity–matrix interface. A couple-loaded rigid harmonic inhomogeneity in the absence of remote loading and in the presence of a concentrated rotational moment at any position in the matrix was also obtained using a similar procedure. [ABSTRACT FROM AUTHOR]

Pile foundations in earthquake-prone areas are subject to overturning moments in which the behavior is dependent on the fixity of the pile tips and characteristics of the stratigraphy of the formation into which the piles are embedded. Further, the bending moment caused by the overturning moment cannot be ignored because the bending moments resulting from the lateral loads and deformation do not cause significant differences in moments irrespective of pile tip fixity. Each model test consisted of four piles identified as Pile A, Pile B, Pile C, and Pile D as shown in Fig. [Extracted from the article]

This paper presents a study on the strength and behavior of cold-formed steel Z-sections with simple and complex stiffeners subjected to major axis bending. The study involved both experimental and numerical investigations, in which a series of specimens were examined. All specimens were failed by the combined mode of shear and moment. The results from the investigations were analyzed and compared with the combined moment and shear strengths predicted by international design rules. The suitability of the design rules in predicting the combined capacity of Z-section with complex stiffeners was assessed through a reliability analysis. [ABSTRACT FROM AUTHOR]

Two full-scale experiments using controlled blasting were conducted in the Port of Tokachi on Hokkaido Island, Japan, to assess the behavior of a single pile, a four-pile group, and a nine-pile group subjected to lateral spreading. The test piles were extensively instrumented with strain gauges to measure the distribution of bending moment during lateral spreading which allowed the backcalculation of the loading conditions, as well as the assessment of damage and performance of the piles. Based on the test results, it was concluded that using controlled blasting successfully liquefied the soil, and subsequently induced lateral spreading in the 4–6% surface slope test beds. The free-field soil displacements in the vicinity of the test piles were over 40 cm for both tests. When compared with the results from the single pile case, the effect of pile head restraint from the pile cap improved overall pile performance by decreasing the displacement of the pile groups and lowering the maximum moments in individual piles within each group. Finally, backcalculated soil reactions indicated that the liquefied soil layer imparted insignificant force to the piles. In the companion to this paper (Part II), an assessment of the potential of using the p–y analysis method for single piles and pile groups subjected to lateral spreading is presented. [ABSTRACT FROM AUTHOR]

Tapered beams are extensively used for structural applications due to their high stiffness-to-mass ratio. They provide many advantages over prismatic beams such as better shear carrying capacity, higher lateral stability, and weight savings. As it is known, axial stress σx=−My/t , from Navier's flexure formula, may be used to estimate bending stresses in tapered beams to some extent, and this can be useful for primary design purposes. However, since the section modulus may vary along the axis of tapered beams, due to the additionally generated shear stress field, the maximum stress cannot necessarily occur at the cross section of the tapered beams where the largest bending moment is present. Nevertheless, classical beam theories do not predict the shear stress distributions in tapered beams if the taper angle is greater than 15°. This study aims at combining the advanced mechanics of a material approach with the theory of elasticity for three different loading conditions applied at the free end of the circular cantilever tapered beams. Derived equations provide the stress distribution across the circular cantilever tapered beams subjected to axial tensile stress, bending moment, and transverse shear force. In order to verify the analytical calculations, a FEM model is employed, and its results shows a reasonable agreement with the analytical results. [ABSTRACT FROM AUTHOR]