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Seismic retrofit of existing structures using friction dampers
, Article Asian Journal of Civil Engineering ; Volume 11, Issue 4 , 2010 , Pages 509-520 ; 15630854 (ISSN) ; Ebrahimian, H ; Sharif University of Technology
2010
Abstract
Conventional methods of seismic rehabilitation with concrete shear walls or steel bracing are not considered suitable for some buildings as upgrades with these methods would have required expensive and time consuming foundation work. Supplemental damping in conjunction with appropriate stiffness offered an innovative and attractive solution for the seismic rehabilitation of such structures. This paper deals with the use of friction damper as a passive dissipative device in order to seismic retrofit of existing structures and discusses the design criteria and seismic analysis of a building. The structure is modeled using the finite element program Sap2000 and is analysed using both non-linear...
Incremental wave analysis and its application to performance-based assessment of jacket platforms
, Article Journal of Constructional Steel Research ; Volume 67, Issue 10 , October , 2011 , Pages 1649-1657 ; 0143974X (ISSN) ; Bagheri, V ; Ebrahimian, H ; Holmas, T ; Sharif University of Technology
2011
Abstract
In this paper, a relatively novel approach is established to estimate different limit states and accurate behavior of jacket platforms against environmental wave loading. This novel approach which is called Incremental Wave Analysis (IWA) can be an appropriate substitute to current pushover practice. The IWA can take into account the effects of variation in wave height and wave-in-deck loading in the estimating of platforms' behavior. This paper aims to introduce the applications of this approach in deterministic assessment of offshore platforms, comprehensively. The IWA can estimate the collapse-prevention limit state of jacket platforms properly. In addition, an appropriate parameter for...
Assessment of offshore platforms under extreme waves by probabilistic incremental wave analysis
, Article Journal of Constructional Steel Research ; Volume 67, Issue 5 , 2011 , Pages 759-769 ; 0143974X (ISSN) ; Ebrahimian, H ; Bagheri, V ; Holmas, T ; Sharif University of Technology
2011
Abstract
In this study, a novel probabilistic framework named Probabilistic Incremental Wave Analysis (PIWA) is established in order to assess the performance of jacket offshore platforms under extreme waves. The PIWA can take into account the uncertainties in three main elements consisting of sea state parameters, structural response and collapse capacity. The main advantage of the PIWA approach is reflected in decoupling of the wave hazard and structural analyses via an intermediate variable known as the wave height intensity measure. Despite the fact that most of the uncertainties associated with structural response are concentrated in wave hazard, this will enable the PIWA to estimate the...
Sensitivity analysis of jacket-type offshore platforms under extreme waves
, Article Journal of Constructional Steel Research ; Volume 83 , 2013 , Pages 147-155 ; 0143974X (ISSN) ; Bahaari, M. R ; Bagheri, V ; Ebrahimian, H ; Sharif University of Technology
2013
Abstract
Jacket-type offshore platforms play an important role in oil and gas industries in shallow and intermediate water depths such as Persian Gulf region. Such important structures need accurate considerations in analysis, design and assessment procedures. In this paper, nonlinear response of jacket-type platforms against extreme waves is examined utilizing sensitivity analyses. Results of this paper can reduce the number of random variables and consequently the computational effort in reliability analysis of jacket platforms, noticeably. Effects of foundation modeling have been neglected in majority of researches on the response of jacket platforms against wave loads. As nonlinear response of...
Land subsidence: a global challenge
, Article Science of the Total Environment ; Volume 778 , 2021 ; 00489697 (ISSN) ; Hosseini, M ; Ataie Ashtiani, B ; Sohani, Y ; Ebrahimian, H ; Morovat, F ; Ashrafi, S ; Sharif University of Technology
Elsevier B.V
2021
Abstract
This study presents a comprehensive review of the Land subsidence (LS) cases, as a worldwide environmental, geological, and global geohazard concern. Here, 290 case studies around the world mostly conducted in large metropolitan cities (e.g. Bangkok, Beijing, California, Houston, Mexico City, Shanghai, Jakarta, and Tokyo) in 41 countries were collected. The spatial distribution of LS characteristics (e.g. intensity, magnitude, and affected area), impacts, and influential factors are scrutinized. Worldwide attempts to remedy the crisis of LS were also investigated in this review. It is shown that the coastal plains and river deltaic regions are of high-frequent subsided areas around the world...