Generalized dynamic Winkler model for nonlinear soil–structure interaction analysis

2008 ◽  
Vol 45 (4) ◽  
pp. 560-573 ◽  
Author(s):  
Nii Allotey ◽  
M. Hesham El Naggar
Keyword(s):  
Soil Structure ◽  
Interaction Analysis ◽  
Soil Structure Interaction ◽  
Winkler Foundation ◽  
Deep Foundations ◽  
Structure Interaction ◽  
Design Engineers ◽  
Winkler Model ◽  
Centrifuge Tests ◽  
Cyclic Degradation

The beam on nonlinear Winkler foundation (BNWF) model is widely used in soil–structure interaction (SSI) analysis owing to its relative simplicity. This paper focuses on the development of a versatile dynamic BNWF model for the analysis of shallow and deep foundations. The model is developed as a stand-alone module to be incorporated in commercial nonlinear structural analysis software. The features of the model discussed are the loading and unloading rules, slack zone development, the modeling of cyclic degradation and radiation damping. The model is shown to be capable of representing various response features observed in SSI experiments. In addition, the predictions of the model for centrifuge tests of piles in weakening and partially weakening soil are shown to be in good agreement with the experimental results. This agreement demonstrates the potential of the model as a useful tool for design engineers involved in seismic design, especially performance-based design.

Non Linear Seismic Pile Soil Structure Interaction Analysis of Piles in Offshore Platforms

2004 ◽  
Author(s):  
Mehrdad Kimiaei ◽  
Mohsen Ali Shayanfar ◽  
M. Hesham El Naggar ◽  
Ali Akbar Aghakouchak
Keyword(s):  
Soil Structure ◽  
Seismic Analysis ◽  
Interaction Analysis ◽  
Site Response ◽  
Free Field ◽  
Soil Structure Interaction ◽  
Model Parameters ◽  
Winkler Foundation ◽  
Offshore Platforms ◽  
Structure Interaction

Pile supported offshore platforms in seismically active areas should be designed to survive severe earthquake excitations with no global structural failure. It is often required to perform nonlinear seismic analysis of offshore platforms that accounts for soil nonlinearity, discontinuity condition at pile soil interfaces, energy dissipation through soil radiation damping and structural nonlinear behaviours of the piles. In this study a BNWF (Beam on Nonlinear Winkler Foundation) model is incorporated into a finite element program (ANSYS) and it is used to compute the lateral response of piles subjected to seismic loading. The soil stiffness is established using the P-Y curve. The results of equivalent linear earthquake free field ground motion analyses are used as the input excitations at support nodes of the model. The components and advantages of this practical ANSYS model in seismic pile soil structure interaction analyses are discussed and addressed in detail. Computed responses compared well with the experimental test results. Sensitivity of the results to model parameters and site response calculations are evaluated.

Free Vibration Analysis of Building Considering Soil Structure Interaction

2016 ◽  
Vol 857 ◽  
pp. 125-130 ◽  
Author(s):  
Thaiba T. Beegam ◽  
Tissa Sebastian
Keyword(s):  
Soil Structure ◽  
Interaction Analysis ◽  
Soft Soil ◽  
Free Vibration Analysis ◽  
Soil Structure Interaction ◽  
Soil Stiffness ◽  
Structure Interaction ◽  
Winkler Model ◽  
Fixed Base ◽  
Flexible Base

Modeling and design of foundation are always done without considering the effect of stiffness of the soil. In the conventional non-interaction analysis of building frame settlements are calculated without considering the influence of the structural stiffness. Therefore a modeling and interaction analysis of soil structure interaction will help to find soil stiffness and effects of soil structure interaction on structure. In this paper, soil structure interaction analysis of a symmetric space frame of 2 bays in both x and y direction are assessed with SAP 2000 software. The frame is modeled with different storey resting on raft foundation with fixed base and flexible base. Three types of soil, i.e. hard, medium, and soft soil are used for Soil Structure Interaction (SSI) study. MODAL analysis is carried out to illustrate the effects of soil-raft-structure interaction on the response of structures. The Soil is considered as Winkler model and elastic continuum model. The developed methodology is validated with results available in the literature. The effects of SSI on frequency of modal are studied. The comparison is carried out the frame with different base conditions.The frequency of the building was found to be decreased when SSI was considered.

State-of-the-Art Techniques for Seismic Soil-Structure Interaction Analysis of Steel Gravity Structures

2014 ◽  
Author(s):  
Frederick Tajirian ◽  
Mansour Tabatabaie ◽  
Basilio Sumodobila ◽  
Stephen Paulson ◽  
Bill Davies
Keyword(s):  
Soil Structure ◽  
State Of The Art ◽  
Interaction Analysis ◽  
Layered Soil ◽  
Soil Structure Interaction ◽  
Soil System ◽  
Cyclonic Storm ◽  
Structure Interaction ◽  
Analysis Methods ◽  
Moderate Seismicity

The design of steel jacket fixed offshore structures in zones of moderate seismicity is typically governed by Metocean loads. In contrast the steel gravity structure (SGS) presented in this paper, is a heavy and stiff structure. The large mass results in foundation forces from seismic events that may exceed those created by extreme cyclonic storm events. When computing the earthquake response of such structures it is essential to account for soil-structure interaction (SSI) effects. Seismic SSI analysis of the SGS platform was performed using state-of-the-art SSI software, which analyzed a detailed three-dimensional model of the SGS supported on layered soil system. The results of this analysis were then compared with those using industry standard impedance methods whereby the layered soil is replaced by equivalent foundation springs (K) and damping (C). Differences in calculated results resulting from the different ways by which K and C are implemented in different software are presented. The base shear, overturning moment, critical member forces and maximum accelerations were compared for each of the analysis methods. SSI resulted in significant reduction in seismic demands. While it was possible to get reasonable alignment using the different standard industry analysis methods, this was only possible after calibrating the KC foundation model with software that rigorously implements SSI effects. Lessons learned and recommendations for the various methods of analysis are summarized in the paper.

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