• Journal of Ocean Engineering and Technology
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• v.21 no.1 s.74
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• pp.69-74
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• 2007

This paper is concerned about the dynamic analysis of an underwater test miner, which operates on cohesive soil. The test miner consists of tracked vehicles and a pick-up device. The motion of the pick-up device, relative to the vehicle chassis, is controlled by two pairs of hydraulic cylinders. The test miner is modeled by means of commercial software. A terramechanics model of cohesive soft soil is implemented with the software and applied to a dynamic analysis of the test miner model. The dynamic responses of the test miner are studied with respect to four different types of terrain conditions.

• Structural Engineering and Mechanics
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• v.33 no.4
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• pp.529-537
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• 2009

A key parameter in the design of a laterally loaded pile is the determination of its performance level. Performance level of a pile is usually expressed as the maximum head deflection and bending moment. In general, uncertainties in the performance of a pile originates from many factors such as inherent variability of soil properties, inadequate soil exploration programs, errors taking place in the determination of soil parameters, limited calculation models as well as uncertainties in loads. This makes it difficult for practicing engineers to decide for the reliability of laterally loaded piles both in cohesive and cohesionless soils. In this paper, limit state functions and consequent performance functions are obtained for single concrete piles to predict the maximum bending moment, a widely accepted design criterion along with the permissible pile head displacement. Analyses were made utilizing three dimensional finite element method and soil-structure-interaction (SSI) effects were accounted for.

• Structural Engineering and Mechanics
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• v.77 no.1
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• pp.37-46
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• 2021

In this study, a method for free vibration analysis of wall-frame systems built on weak soil is proposed. In the development of the method, the wall-frame system that constitutes the superstructure was modeled as flexural-shear beam. In the study, it is accepted that the soil layers are isotropic, homogeneous and elastic, and the waves are only vertical propagating shear waves. Based on this assumption, the soil layer below is modeled as an equivalent shear beam. Then the differential equation system that represented the behavior of the whole system was written for both regions in a separate way. Natural periods were obtained by solving the differential equations by employing boundary conditions. At the end of the study, two examples were solved and the suitability of the proposed method to the Finite Element Method was evaluated.

• Structural Engineering and Mechanics
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• v.83 no.3
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• pp.377-386
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• 2022

This paper considers dynamic impedance functions and presents a detailed analysis of the soil plasticity influence on the pile-group foundation dynamic response. A three-dimensional finite element model is proposed, and a calculation method considering the time domain is detailed for the nonlinear dynamic impedance functions. The soil mass is modeled as continuum elastoplastic solid using the Mohr-Coulomb shear failure criterion. The piles are modeled as continuum solids and the slab as a structural plate-type element. Quiet boundaries are implemented to avoid wave reflection on the boundaries. The model and method of analysis are validated by comparison with those published on literature. Numerical results are presented in terms of horizontal and vertical nonlinear dynamic impedances as a function of the shear soil parameters (cohesion and internal friction angle), pile spacing ratio and frequencies of the dynamic signal.

• Coupled systems mechanics
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• v.11 no.5
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• pp.373-387
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• 2022

In this paper,soil-structure interaction effects on the seismic response of multistory frame structure on raft foundation are numerically analyzed. The foundation soil profile is assumed to consists of a clay layer of variable thicknessresting on bedrock. Amodified plane-strain numerical model isformed in the software Plaxis, and both free vibration analysis, and earthquake analysis for a selected ground motion accelerogram are performed. The behavior of the structure is assumed to be linear elastic with Rayleigh viscous damping included. The behavior of the clay layer is modeled with a Hardening soil model with small strain stiffness. The computed results in terms of fundamental period and structural horizontal displacementsfor the case of fixed base and for different thicknesses of clay layer are presented, compared, and discussed.

• Structural Engineering and Mechanics
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• v.86 no.1
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• pp.85-92
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• 2023

This article examines the seismic vulnerability of soil nail wall structures. Detailed information regarding finite element modeling has been provided. The fragility function evaluates the relationship between ground motion intensities and the probability of surpassing a specific level of damage. The use of incremental dynamic analysis (IDA) has been applied to the soil nail wall against low to severe ground motions. In the nonlinear dynamic analysis of the soil nail wall, a set of twenty seismic ground motions with varying PGA ranges are used. The numerical results demonstrate that the soil-nailed wall reaction is extremely sensitive to earthquake ground vibrations under different intensity measures (IM). In addition, the analytical fragility curve is provided for various intensity values.

• Coupled systems mechanics
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• v.13 no.3
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• pp.187-200
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• 2024

This paper presents a numerical model for buckling analysis of slender piles, such as micropiles. The model incorporates geometric nonlinearities to provide enhanced accuracy and a more comprehensive representation of pile buckling behavior. Specifically, the pile is represented using geometrically nonlinear beams with the von Karman deformation measure. The lateral support provided by the surrounding soil is modeled using the spring approach, with the spring stiffness determined according to the undrained shear strength of the soil. The numerical model is tested across a wide range of pile slenderness ratios and undrained shear strengths of the surrounding soil. The numerical results are validated against analytical solutions. Furthermore, the influence of various pile bottom end boundary conditions on the critical buckling force is investigated. The implications of the obtained results are thoroughly discussed.

• Structural Engineering and Mechanics
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• v.88 no.3
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• pp.273-285
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• 2023

This study examines how the interaction between soil and a wind turbine's supporting system affects the optimal design. The supporting system resting on an elastic soil foundation consists of a steel conical tower and a concrete circular raft foundation, and it is subjected to wind loads. The material cost of the supporting system is aimed to be minimized employing various metaheuristic optimization algorithms including teaching-learning based optimization (TLBO). To include the influence of the soil in the optimization process, modified Vlasov and Gazetas elastic soil models are integrated into the optimization algorithms using the application programing interface (API) feature of the structural analysis program providing two-way data flow. As far as the optimal designs are considered, the best minimum cost design is achieved for the TLBO algorithm, and the modified Vlasov model makes the design economical compared with the simple Gazetas and infinitely rigid soil models. Especially, the optimum design dimensions of the raft foundation extremely reduce when the Vlasov realistic soil reactions are included in the optimum analysis. Additionally, as the designated design wind speed is decreased, the beneficial impact of soil interaction on the optimum material cost diminishes.

• Interaction and multiscale mechanics
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• v.1 no.1
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• pp.33-51
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• 2008

This paper investigates the modelling of coupled soil-structure interaction problems by domain decomposition techniques. It is assumed that the soil-structure system is physically partitioned into soil and structure subdomains, which are independently modelled. Coupling of the separately modelled partitioned subdomains is undertaken with various algorithms based on the sequential iterative Dirichlet-Neumann sub-structuring method, which ensures compatibility and equilibrium at the interface boundaries of the subdomains. A number of mathematical and computational characteristics of the coupling algorithms, including the convergence conditions and choice of algorithmic parameters leading to enhanced convergence of the iterative method, are discussed. Based on the presented coupling algorithms a simulation environment, utilizing discipline-oriented solvers for nonlinear structural and geotechnical analysis, is developed which is used here to demonstrate the performance characteristics and benefits of various algorithms. Finally, the developed tool is used in a case study involving nonlinear soil-structure interaction analysis between a plane frame and soil subjected to ground excavation. This study highlights the relative performance of the various considered coupling algorithms in modelling real soil-structure interaction problems, in which nonlinearity arises in both the structure and the soil, and leads to important conclusions regarding their adequacy for such problems as well as the prospects for further enhancements.

• Structural Engineering and Mechanics
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• v.68 no.2
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• pp.159-170
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• 2018

This paper aims to develop response modification factors for stiffness degrading structures by incorporating soil-structure interaction effects. A comprehensive parametric study is conducted to investigate the effects of key SSI parameters, natural period of vibration, ductility demand and hysteretic behavior on the response modification factor of soil-structure systems. The nonlinear dynamic response of 6300 soil-structure systems are studied under two ensembles of accelograms including 20 recorded and 7 synthetic ground motions. It is concluded that neglecting the stiffness degradation of structures can results in up to 22% underestimation of inelastic strength demands in soil-structure systems, leading to an unexpected high level of ductility demand in the structures located on soft soil. Nonlinear regression analyses are then performed to derive a simplified expression for estimating ductility-dependent response modification factors for stiffness degrading soil-structure systems. The adequacy of the proposed expression is investigated through sensitivity analyses on nonlinear soil-structure systems under seven synthetic spectrum compatible earthquake ground motions. A good agreement is observed between the results of the predicted and the target ductility demands, demonstrating the adequacy of the expression proposed in this study to estimate the inelastic demands of SSI systems with stiffness degrading structures. It is observed that the maximum differences between the target and average target ductility demands was 15%, which is considered acceptable for practical design purposes.