• Geomechanics and Engineering
• /
• v.37 no.2
• /
• pp.189-195
• /
• 2024

Buried pipelines can be classified as continuous and segmented pipelines. These infrastructures can be damaged either by ground movement or by seismic wave propagation during an earthquake. Permanent ground deformations (PGD) include surface faulting, liquefaction-induced lateral spreading and landslide. Liquefaction is a major problem for both superstructures and infrastructures. Buyukcekmece lake zone, which is the studied region in this paper, is a liquefaction prone area located near the North Anatolian Fault Line. It is an active fault line in Turkey and a major earthquake with a magnitude of around 7.5 is expected in this investigated region in Istanbul. It is planned to be constructed a new 12" steel natural gas pipeline from one side of the lake to the other side. In this study, this case has been examined in terms of two different support conditions. Firstly, it has been defined as a beam in liquefied soil and has built-in supports at both ends. In the other approach, this case has been modeled as a beam in liquefied soil and has vertical elastic pinned supports at both ends. These models have been examined and some solution proposals have been produced according to the obtained results. In this study, based on this sample, it is aimed to determine the behaviors of buried continuous pipelines subject to liquefaction effects in terms of buoyancy.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.04a
• /
• pp.1049-1052
• /
• 2008

Coupling beams have been used in bearing wall system during last decades. Practically their sectional effects are fully considered in analysis stage to control lateral displacement because they have good contribution to the stiffness of bearing wall system. But the high resultant forces of coupling beam are not fully satisfied in design stage because coupling beams are restricted in sectional size. In this paper the performance of bearing wall system with coupling beam has been evaluated based on improved equivalent linearization procedure of FEMA 440. 15 storied building is selected for analysis. Variables for performance evaluation are natural period, degree of coupling and soil site. To evaluate performance, demand capacity spectrum is calculated based on KBC 2005. As a result, for the most of the cases the life safety limit of chord rotation of coupling beam is less than the performance point of system for soil site $S_D$. That means that the coupling beam can be severly damaged before the system reaches at performance point.

• Geomechanics and Engineering
• /
• v.24 no.4
• /
• pp.371-388
• /
• 2021

A novel flexibility-based beam-foundation model for inelastic analyses of beams resting on foundation is presented in this paper. To model the deformability of supporting foundation media, the Winkler-Pasternak foundation model is adopted. Following the derivation of basic equations of the problem (strong form), the flexibility-based finite beam-foundation element (weak form) is formulated within the framework of the matrix virtual force principle. Through equilibrated force shape functions, the internal force fields are related to the element force degrees of freedom. Tonti's diagrams are adopted to present both strong and weak forms of the problem. Three numerical simulations are employed to assess validity and to show effectiveness of the proposed flexibility-based beam-foundation model. The first two simulations focus on elastic beam-foundation systems while the last simulation emphasizes on an inelastic beam-foundation system. The influences of the adopted foundation model to represent the underlying foundation medium are also discussed.

• Structural Engineering and Mechanics
• /
• v.46 no.5
• /
• pp.645-672
• /
• 2013

The differential settlements and rotations among footings cannot be avoided when the frame-footing-soil system is subjected to seismic/dynamic loading. Also, there may be a situation where column(s) of a building are located near adjoining property line causes eccentric loading on foundation system. The strap beams may be provided to control the rotation of the footings within permissible limits caused due to such eccentric loading. In the present work, the seismic interaction analysis of a three-bay three-storey, space frame-footing-strap beam-soil system is carried out to investigate the interaction behavior using finite element software (ANSYS). The RCC structure and their foundation are assumed to behave in linear manner while the supporting soil mass is treated as nonlinear elastic material. The seismic interaction analyses of space frame-isolated footing-soil and space frame-strap footing-soil systems are carried out to evaluate the forces in the columns. The results indicate that the bending moments of very high magnitude are induced at column bases resting on eccentric footing of frame-isolated footing-soil interaction system. However, use of strap beams controls these moments quite effectively. The soil-structure interaction effect causes significant redistribution of column forces compared to non-interaction analysis. The axial forces in the columns are distributed more uniformly when the interaction effects are considered in the analysis.

• Geotechnical Engineering
• /
• v.12 no.3
• /
• pp.149-164
• /
• 1996

The sequential behavior of earth retaining structure is investigated by using soil springs in elasto -plastic soil. Mathematical model that can be used to construct the p-y curves for subgrade modulus is proposed by using piecewise linear function. The excavation sequence of retaining wall is analyzed by the beam -column method. Reliability on the developed computer program is verfied through the comparison between the prediction and the in -situ measuidments. It is concluded that the proposed method simulates well the construction sequence and thus represents a significant improvement in the prediction of deflections of anchored wall excavation. Based on the results the proposed method can be effectively used for the evaluation of the relative importance of the parameters employed in a sensitivity analysis.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 2000.04a
• /
• pp.443-450
• /
• 2000

In this study a numerical method for soil-pile interaction analysis buried in multi-layered half planes is presented in frequency domain using FE-BE coupling. The total soil-pile interaction system is divided into two parts so called far field and near field beam elements are used for modeling a pile and coupled with plain strain elements for soil modeling. Boundary element formulation using the multi-layered dynamic fundamental solution is adopted to the far field and coupled with near field modeled by finite elements. In order to verify the proposed soil-pile interaction analysis method the dynamic responses of a pile on multi-layered dynamic fundamental solution is adopted to the far field and coupled with near field modeled by finite elements. In order to verify the proposed soil-pile interaction analysis method the dynamic responses of a pile on multi-layered half-planes are performed and compared with experiment results. Through this developed method the dynamic response analysis of a pile buried in multi-layered half planes can be calculated effectively in frequency domain.

• Magazine of korean Tunnelling and Underground Space Association
• /
• v.21 no.2
• /
• pp.117-129
• /
• 2019

Tunnelling in urban environments is very common nowadays as large cities are expanding and transportation demands require the use of the underground space for creating extra capacity. Inevitably, any such new construction may have significant effects on existing nearby infrastructure and therefore relevant assessment of structural integrity and soil-structure interaction is required. Foundation piles can be rather sensitive to nearby tunnel construction and therefore their response needs to be evaluated carefully. Although detailed three-dimensional continuum finite element analysis can provide a wealth of information about this behaviour of piles, such analyses are generally very computationally demanding and may require a number of material and other model parameters to be properly calibrated. Therefore, relevant simplified approaches are used to provide a practical way for such an assessment. This paper presents a simple method where the pile is modelled with beam finite elements, pile-soil interaction is modelled with soil springs and tunnelling-induced displacements are introduced as an input boundary condition at the end of the soil springs. The performance of this approach is assessed through some examples of applications.

• Ocean Systems Engineering
• /
• v.9 no.3
• /
• pp.241-259
• /
• 2019

This paper presents a fully three-dimensional numerical approach for analyzing deepwater drilling riser-conductor system vortex-induced vibrations (VIV) including nonlinear soil-structure interactions (SSI). The drilling riser-conductor system is modeled as a tensioned beam with linearly distributed tension and is solved by a fully implicit discretization scheme. The fluid field around the riser-conductor system is obtained by Finite-Analytic Navier-Stokes (FANS) code, which numerically solves the unsteady Navier-Stokes equations. The SSI is considered by modeling the lateral soil resistance force according to nonlinear p-y curves. Overset grid method is adopted to mesh the fluid domain. A partitioned fluid-structure interaction (FSI) method is achieved by communication between the fluid solver and riser motion solver. A riser-conductor system VIV simulation without SSI is firstly presented and served as a benchmark case for the subsequent simulations. Two SSI models based on a nonlinear p-y curve are then applied to the VIV simulations. Also, the effects of two key soil properties on the VIV simulations of riser-conductor systems are studied.

• Structural Engineering and Mechanics
• /
• v.68 no.1
• /
• pp.121-130
• /
• 2018

This study deals with optimum geometry design of laterally loaded piles in a Winkler's medium through the Fully Stressed Design (FSD) method. A numerical algorithm distributing the mass by means of the FSD method and updating the moment by finite elements is implemented. The FSD method is implemented here using a simple procedure to optimise the beam length using an approach based on the calculus of variations. For this aim two conditions are imposed, one transversality condition at the bottom end, and a one sided constraint for moment and mass distribution in the lower part of the beam. With this approach we derive a simple condition to optimise the beam length. Some examples referred to different fields are reported. In particular, the case of laterally loaded piles in Geotechnics is faced.

• Structural Engineering and Mechanics
• /
• v.51 no.5
• /
• pp.727-741
• /
• 2014

The functionally graded beam (FGB) is investigated in this study on both dynamic and static loading in case of resting on a soil medium rather than on the usual Winkler-Pasternak elastic foundation. The powerful ABAQUS software was used to model the problem applying finite element method. In the present study, two different soil models are taken into account. In the first model, the soil is assumed to be an elastic plane stress medium. In the second soil model, the Drucker-Prager yield criterion, which is one of the most well-known elastic-perfectly plastic constitutive models, is used for modelling the soil medium. The results are shown to evaluate the effects of the different soil models, stiffness values of the elastic soil medium on the normal and shear stress and free vibration properties. A comparison was made to those from the existing literature. Numerical results show that considering real soil as a continuum space affects the results of the bending and the modal properties significantly.