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Seismic Analysis of Offshore Patformsusing Endurance Time Method
, M.Sc. Thesis Sharif University of Technology ; Esmaeil Pourestekanchi, Homayun (Supervisor) ; Golafshani, Ali Akbar (Supervisor)
Abstract
In the countries with offshore oil field, Such as Iran, Offshore platforms are important. Hence seismic analysis of offshore platforms is important. Different methods for seismic assessment of these structures are presented. But these methods has own advantage and disadvantages. (Such as long analysis time and simplified assumptions of linear behavior), but by using Endurance Time method, the method had shown the ability to analyze complex structures, It is hoped that these problems can be resolved. In this study, providing a suitable model of soil and structures of a single pile and then an offshore platform using DEEPSOIL and Open SEES software and performance of these structures at...
Numerical Thermo-Mechanical Analysis of Single Thermal Piles in Clay
,
M.Sc. Thesis
Sharif University of Technology
;
Ahmadi, Mohammad Mehdi
(Supervisor)
Abstract
In recent years, growth of industries has led to consistent increase in energy consumption around the globe. On the other hand, non-renewable energy sources are the most consumed ones in the world. Therefore, governments and companies have tried to introduce budgets to facilitate the use of renewable energy sources and make their use cheaper. One of the renewable energy sources is geothermal energy which one economical way to havest it is thermal energy exchange between the building foundation and the ground. Therfore, thermal piles , by the use of a heat exchanger fluid, transfer the heat on the surface to the ground in warmer seasons and in cold seasons, they transfer the heat from the...
Liquefaction Effects on (a) Individual and Group of Capless Piles and (b) Group of three Piles under Real and Artificial Earthquakes
, M.Sc. Thesis Sharif University of Technology ; Haeri, Mohsen (Supervisor)
Abstract
In the areas where the soil beneath the foundation is made of loose to semi-consolidated sand or noncohesive silts, Buildings and bridges are usually built on the pile foundations. One important issue that must be considered in the design of piles in saturated sandy soils, is liquefaction potential of saturated sandy soil under earthquake loads. During the earthquake, saturated sandy soil faces the sudden loss of shear strength in other word it liquifies . Liquefied Soil acts like a viscous fluid. This behaviour considerably increases the soil deformation and consequently the widespread disruption of soil layers, causes large deformation and applies great amount of forces on the piles...
Numerical Modeling of the Dynamic Behavior of Piles and Pile Groups Due to Liquefaction- Induced Lateral Spreading
, M.Sc. Thesis Sharif University of Technology ; Haeri, Mohsen (Supervisor)
Abstract
The phenomenon of lateral spreading occurs as a consequence of earthquakes induced liquefaction in grounds with mild slopes or ending to an opening. This phenomenon has caused many damages to deep foundations and associated structures. Therefore, it is necessary to study and estimate the forces which may be induced by lateral spreading to these structures. Due to the complex mechanism of the effect of lateral spreading on the piles, various tests have been carried out in the form of shaking table as well as centrifuge tests. According to the results of these tests, the forces applied to the piles are significant and can cause crucial damages to deep foundations. On the other hand, because...
Numerical modeling of piles in sandy soils considering stress dependent modulus of elasticity
, Article Computer Methods and Recent Advances in Geomechanics - Proceedings of the 14th Int. Conference of International Association for Computer Methods and Recent Advances in Geomechanics, IACMAG 2014, 22 September 2014 through 25 September 2014, Kyoto ; 2015 , Pages 973-977 ; 9781138001480 (ISBN) ; Abadi, S. M ; Sharif University of Technology
Taylor and Francis - Balkema
2015
Abstract
Pile Foundations are used to transfer loads from superstructures to the underlying competent soil layers. Predicting pile bearing capacity is among the most interesting subjects for geotechnical engineers. In this study, a single pile is modeled in axisymmetric condition. The soil is considered to be a sandy soil. Then, results of the model were verified with a full scale pile load test performed by previous researchers. In order to take into consideration the real behavior of sandy soils, a variation of modulus of elasticity with respect to the changes in the mean effective stress was taken into account. The dependency of soil modulus to the mean effective stress makes the model more...
Seismic performance evaluation of jacket-type offshore platforms using endurance time method considering soil-pile-superstructure interaction
, Article Scientia Iranica ; Volume 24, Issue 4 , 2017 , Pages 1843-1854 ; 10263098 (ISSN) ; Golafshani, A. A ; Estekanchi, H. E ; Sharif University of Technology
Sharif University of Technology
2017
Abstract
In this paper, application of Endurance Time (ET) method in nonlinear seismic analysis of offshore pile supported systems has been studied. The ET method is a time-history analysis in which structures are subjected to intensifying artificial acceleration functions. The ET method reduces complexity and computational demand of conventional nonlinear seismic analysis, and it provides response at different seismic levels in a single ET analysis. The aforementioned methodology has been applied to a typical model of single pile and then to a functional jacket offshore platform in Persian Gulf region. Seismic response of aforesaid models by ET method has been compared with conventional time-history...
Physical Modeling of Energy Pile Behavior under Thermo-Mechanical Loading
, M.Sc. Thesis Sharif University of Technology ; Jafarzadeh, Fardin (Supervisor)
Abstract
A heat exchanger pile is a pile that is equipped with absorber pipes so that it can exchange heat with the surrounding soil. These piles couple the structural support role of conventional piles to the heat exchanger role of shallow geothermal systems for any built environment. So They are subjected to both mechanical and thermal loads. The use of these piles can be useful in reducing greenhouse gas emissions and reducing fossil fuel consumption. In order to study the thermomechanical behavior of heat exchanger piles, a physical model has been constructed in the Advanced Soil Mechanics Laboratory of the School of Civil Engineering at Sharif University of Technology. In this physical model,...
Response of a group of piles to liquefaction-induced lateral spreading by large scale shake table testing
, Article Soil Dynamics and Earthquake Engineering ; Volume 38 , 2012 , Pages 25-45 ; 02677261 (ISSN) ; Kavand, A ; Rahmani, I ; Torabi, H ; Sharif University of Technology
2012
Abstract
Liquefaction-induced lateral spreading has imposed severe damages to many important structures supported on pile foundations during past earthquakes. As a result, evaluation of pile response to lateral spreading is an important step towards safe and resistant design of pile foundations against this destructive phenomenon. Current paper aims to study the response of a group of piles subjected to liquefaction-induced lateral spreading using a large scale 1-g shake table test. General test results including time-histories of accelerations, pore water pressures, displacements and bending moments are presented and discussed in this paper. In addition, distribution of lateral soil pressure on...