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.

Simplified Soil–Structure Interaction Analysis for High-Tech Industrial Buildings Subjected to Forced Vibrations

2015 ◽  
Vol 15 (01) ◽  
pp. 1450031 ◽  
Author(s):  
Shi-Shuenn Chen ◽  
Jun-Yang Shi
Keyword(s):  
Soil Structure ◽  
Interaction Analysis ◽  
Dynamic Responses ◽  
Soil Structure Interaction ◽  
High Tech ◽  
System Response ◽  
Soil System ◽  
Structure Interaction ◽  
Industrial Buildings ◽  
Design Values

To implement a safe and reliable design for high-tech industrial buildings, the system response should be accurate enough to include the effect of soil–structure interaction (SSI). This study proposed a simplified building–soil system to analyze the dynamic responses, using parameters that are representative of the practical design values for typical semiconductor fab structures in Taiwan. The responses of the simplified building–soil system subjected to dynamic horizontal loadings are verified in the frequency domain and time domain. The dynamic responses of the simplified building–soil system are found to agree very well with those of the complete system obtained by the half-space theory and by the numerical analysis program. It is shown that the proposed simplified system can effectively analyze the coupled SSI effects in the translational and rotational directions. It is also found that the structural responses may deviate significantly by neglecting the coupling of horizontal and rocking motions as the building has a deeper embedded foundation and a stiffer upper structure. The proposed method can be applied to the vibration analysis of high-tech industrial buildings subjected to dynamic loadings.

Soil Structure Interaction Analysis of a Berthing Structure Under Lateral Loading-By Numerical Approach

2017 ◽  
Author(s):  
Perumalsamy Kavitha ◽  
Ranganathan Sundaravadivelu
Keyword(s):  
Soil Structure ◽  
Interaction Analysis ◽  
Numerical Study ◽  
Soil Structure Interaction ◽  
Laterally Loaded Piles ◽  
Soil System ◽  
Structure Interaction ◽  
Earthquake Force ◽  
Laterally Loaded ◽  
Interaction Problem

In coastal and offshore structures, the predominant forces leading to lateral movements are mainly due to waves, currents, winds, berthing forces, mooring forces and lateral earth pressure due to unstable slope as a result of dredging or siltation etc. Due to relative movement between the piles and the soil, the load transfer to pile is a complex soil interaction problem. It is a two way problem and should be solved by structure-soil model with appropriate load displacement characteristics of both the structure and the soil. Pile-soil interaction analysis is carried out by numerical methods based on iterative techniques of equilibrium of forces and moments, based on relative stiffness of pile-soil system. Conventionally API guidelines and Vesic equation are used to analyze the laterally loaded piles. The study of laterally loaded pile in active soil wedge requires a proper assessment of soil structure interaction phenomenon involving the interaction between pile surface and the surrounding soil. The instability of soil wedge can occur due to self-weight, surcharge load, dredging, siltation and earthquake force. The soil structure interaction problem of piles located in active soil wedge has rarely been approached. Laterally loaded piles are analyzed by methods derived from the classical beam on elastic foundation mode in which the soil support is approximated by a series of independent elastic spring. The soil spring constants estimated from API guidelines and Vesic equations are not suitable for piles located in active soil wedge. Hence in this paper, a numerical study is carried out for a berthing structure in dense sand using PLAXIS 3D and STAAD Pro, in order to study the behaviour of piles in active soil wedge.

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