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Buckling behavior of the anchored steel tanks under horizontal and vertical ground motions using static pushover and incremental dynamic analyses
, Article Thin-Walled Structures ; Volume 112 , 2017 , Pages 173-183 ; 02638231 (ISSN) ; Rahimzadeh Rofooei, F ; Khajeh Ahmad Attari, N ; Sharif University of Technology
Elsevier Ltd
2017
Abstract
This paper investigates the static and dynamic buckling of an anchored cylindrical steel tank subjected to horizontal and vertical ground acceleration. The buckling capacity of the tank is estimated using static pushover (SPO) and incremental dynamic analyses (IDA). Appropriate load patterns due to the horizontal and vertical components of ground excitations are utilized for SPO analyses. The buckling capacity curves and critical buckling loads computed using SPO analyses are compared to those obtained from IDA. A proper vertical to horizontal acceleration ratio (av/ah) for SPO analysis is proposed that leads to good agreement between SPO and IDA results. © 2017
Performance of buried gas distribution pipelines subjected to reverse fault movement
, Article Journal of Earthquake Engineering ; Volume 22, Issue 6 , 2018 , Pages 1068-1091 ; 13632469 (ISSN) ; Rahimzadeh Rofooei, F ; Khajeh Ahmad Attari, N ; Sharif University of Technology
Taylor and Francis Ltd
2018
Abstract
In the current work, the results of full-scale laboratory testing of 114.3 and 168.3 mm in diameter steel gas distribution pipes buried at different depths and in two different soil types under a reverse fault offset of 0.6 m are presented and discussed in terms of longitudinal strain distribution, pipe deformation, and cross-section distortion. Results show that the pipe deformation and accordingly its failure mode, and soil failure planes change with increasing burial depth. It was also found that severe cross-section distortion occurs at about 2.3 times the strain limit for onset of wrinkling suggested by various guidelines. © 2018, © 2018 Taylor & Francis Group, LLC
Performance of buried gas distribution pipelines subjected to reverse fault movement
, Article Journal of Earthquake Engineering ; 2017 , Pages 1-24 ; 13632469 (ISSN) ; Rahimzadeh Rofooei, F ; Khajeh Ahmad Attari, N ; Sharif University of Technology
2017
Abstract
In the current work, the results of full-scale laboratory testing of 114.3 and 168.3 mm in diameter steel gas distribution pipes buried at different depths and in two different soil types under a reverse fault offset of 0.6 m are presented and discussed in terms of longitudinal strain distribution, pipe deformation, and cross-section distortion. Results show that the pipe deformation and accordingly its failure mode, and soil failure planes change with increasing burial depth. It was also found that severe cross-section distortion occurs at about 2.3 times the strain limit for onset of wrinkling suggested by various guidelines. © 2017 Taylor & Francis Group, LLC
On lateral response of structures containing a cylindrical liquid tank under the effect of fluid/structure resonances
, Article Journal of Sound and Vibration ; Volume 318, Issue 4-5 , 2008 , Pages 1154-1179 ; 0022460X (ISSN) ; Rahimzadeh Rofooei, F ; Sharif University of Technology
Academic Press
2008
Abstract
The lateral response of a single degree of freedom (SDOF) structural system containing a rigid circular cylindrical liquid tank, under harmonic and earthquake excitations is considered. The governing differential equations of motion for the combined system is derived considering the first 3 liquid sloshing modes (1,1), (0,1), and (2,1), under horizontal excitation. The system is considered nonlinear due to the convective term of liquid acceleration and the nonlinear surface boundary conditions, both caused by the inertial nonlinearity. The harmonic and seismic response of the system is investigated in the neighborhood of 1:1 and 1:2 internal resonances between the SDOF system and the first...
Experimental and finite element study of the reverse faulting effects on buried continuous steel gas pipelines
, Article Soil Dynamics and Earthquake Engineering ; Volume 86 , 2016 , Pages 1-14 ; 02677261 (ISSN) ; Rahimzadeh Rofooei, F ; Khajeh Ahmad Attari, N ; Samadian, M ; Sharif University of Technology
Elsevier Ltd
2016
Abstract
Permanent ground displacement (PGD) caused by surface faulting is considered as one of the most significant hazards affecting buried pipelines. Pipelines crossing reverse-slip faults are subjected to compressive actions (stresses and strains) which can result in buckling of the pipe. In current work, the results obtained from the full-scale laboratory testing and finite element analyses of 4″ (114.3 mm) and 6″ (168.3 mm) steel gas pipes (without internal pressure) buried inside a split box and subjected to a reverse faulting of 0.6 m (pure dip-slip) are presented. These pipes are commonly used in gas distribution lines and networks. The experimental setup, procedure and instrumentation as...
Static and dynamic pushover analysis of steel moment resisting frames
, Article 10th East Asia-Pacific Conference on Structural Engineering and Construction, EASEC 2010, Bangkok, 3 August 2006 through 5 August 2006 ; Volume 3 , 2006 , Pages 459-464 ; 9748257231 (ISBN); 9789748257235 (ISBN) ; Rahimzadeh Rofooei, F ; Khajeh Ahmad Attari, N ; Shodja, A. H ; Sharif University of Technology
2006
Abstract
Pushover analysis is a simplified nonlinear analysis technique that can be used to estimate the dynamic demands imposed on a structure under earthquake excitations. One of the first steps taken in this approximate solution is to assess the maximum roof displacement, known as target displacement, using the base shear versus roof displacement diagram. That could be done by the socalled dynamic pushover analysis, i.e. a dynamic time history analysis of an equivalent single degree of freedom model of the original system, as well as other available approximate static methods. In this paper, a number of load patterns, including a new approach, are considered to construct the related pushover...
Adaptive pushover analysis
, Article 10th East Asia-Pacific Conference on Structural Engineering and Construction, EASEC 2010, Bangkok, 3 August 2006 through 5 August 2006 ; Volume 3 , 2006 , Pages 453-458 ; 9748257231 (ISBN); 9789748257235 (ISBN) ; Rasekh, A ; Shodja, A. H ; Khajeh Ahmad Attari, N ; Sharif University of Technology
2006
Abstract
Nonlinear static methods are simplified procedures in which the problem of evaluating the maximum expected response of a MDOF system for a specified level of earthquake motion is replaced by response evaluation of its equivalent SDOF system. The common features of these procedures are the use of pushover analysis to characterize the structural system. In pushover analysis both the force distribution and the target displacement are based on the assumptions that the response is controlled by the fundamental mode and that the mode shape remains unchanged after the structure yields. Therefore the invariant force distributions does not account for the change of load patterns caused by the plastic...
On nonlinear perturbation analysis of a structure carrying a circular cylindrical liquid tank under horizontal excitation
, Article JVC/Journal of Vibration and Control ; Volume 25, Issue 5 , 2019 , Pages 1058-1079 ; 10775463 (ISSN) ; Rahimzadeh Rofooei, F ; Waezi, Z ; Sharif University of Technology
SAGE Publications Inc
2019
Abstract
The lateral response of a single degree of freedom structural system containing a rigid circular cylindrical liquid tank under harmonic and earthquake excitations at a 1:2 autoparametric resonance case is considered. The governing nonlinear differential equations of motion for the combined system are solved by means of a multiple scales method considering the first three liquid sloshing modes (1,1), (0,1), and (2,1), under horizontal excitation. The fixed points of the gyroscopic type of governing differential equations are determined and their stability is investigated employing the perturbation method. The obtained results reveal an increase in the stability region for a single-mode...
Parametric study of buried steel and high density polyethylene gas pipelines due to oblique-reverse faulting
, Article Canadian Journal of Civil Engineering ; Volume 42, Issue 3 , 2015 , Pages 178-189 ; 03151468 (ISSN) ; Hojat Jalali, H ; Khajeh Ahmad Attari, N ; Kenarangi, H ; Samadian, M ; Sharif University of Technology
National Research Council of Canada
2015
Abstract
A numerical study is carried out on buried steel and high density polyethylene (HDPE) pipelines subjected to oblique-reverse faulting. The components of the oblique-reverse offset along the horizontal and normal directions in the fault plane are determined using well-known empirical equations. The numerical model is validated using the experimental results and detailed finite element model of a 114.3 mm (4==) steel gas pipe subjected to a reverse fault offset up to 0.6 m along the faulting direction. Different parameters such as the pipe material, the burial depth to the pipe diameter ratio (H/D), the pipe diameter to wall thickness ratio (D/t), and the fault–pipe crossing angle are...
Investigation the Effect of Fluid/Structure Interaction on the Seismic Response of Structure Containing a Cylindrical Liquid Tank
, Ph.D. Dissertation Sharif University of Technology ; Rahimzadeh Rofooei, Fayyaz (Supervisor)
Abstract
The lateral response of a Single Degree of Freedom (SDOF) structural system containing a rigid circular cylindrical liquid tank, under harmonic and earthquake excitations is considered. The governing differential equations of motion for the combined system is derived considering the first three liquid sloshing modes (1,1), (0,1), and (2,1), under horizontal excitation. The system is considered nonlinear due to the convective term of liquid acceleration and the nonlinear surface boundary conditions, both caused by the inertial nonlinearity. The harmonic and seismic response of the system is investigated in the neighborhood of 1:1 and 1:2 internal resonances between the SDOF system and the...
Experimental and Numerical Investigation of the Behavior of Buried Pipes Subjected to Permanent Ground Deformation Caused by Reverse Faulting
, Ph.D. Dissertation Sharif University of Technology ; Rahimzadeh Rofooei, Fayaz (Supervisor) ; Khajeh Ahmad Attari, Nader (Co-Advisor)
Abstract
In this study the behavior of buried pipes under permanent ground deformation (PGD) ef-fects caused by reverse faulting is investigated by means of both experimental and numeri-cal approaches. A total number of 7 full-scale experiments on buried steel pipes subjected to a fault offset of 0.6 m along the slip plane is carried out and the effects of different pa-rameters such as pipe diameter (114.3 mm (4ʺ) and 168.3 mm (6ʺ)), burial depth (0.25m, 0.5m, 1 m) and soil type (SW and SM) on the response of the buried pipes are studied. Ex-perimental results show that the pipe deformation shape changes with increasing burial depth from half-sine (for shallow depths) to an S-shape (for moderate to...
Vibration control through the robust nonlinear absorber with negative stiffness and internal resonance creation
, Article JVC/Journal of Vibration and Control ; 2022 ; 10775463 (ISSN) ; Khajeh Ahmad Attari, N ; Rahimzadeh Rofooei, F ; Sharif University of Technology
SAGE Publications Inc
2022
Abstract
In this study, a nonlinear absorber that works with a negative stiffness mechanism is suggested to mitigate vibration, and its effect on the reduction of vibration is investigated. The negative stiffness, which is inherently nonlinear, creates internal resonance; therefore, the vibration energy can be transmitted from low-frequency to high-frequency vibrating modes, causing vibration suppression. The nonlinear absorber is added to the primary nonlinear system, and when the main system is subjected to external resonance due to harmonic excitation, the negative stiffness parameter of absorber is so adjusted that autoparametric resonance occurs and vibration is reduced. First, the mathematical...
Vibration control through the robust nonlinear absorber with negative stiffness and internal resonance creation
, Article JVC/Journal of Vibration and Control ; Volume 29, Issue 5-6 , 2023 , Pages 1254-1267 ; 10775463 (ISSN) ; Khajeh Ahmad Attari, N ; Rahimzadeh Rofooei, F ; Sharif University of Technology
SAGE Publications Inc
2023
Abstract
In this study, a nonlinear absorber that works with a negative stiffness mechanism is suggested to mitigate vibration, and its effect on the reduction of vibration is investigated. The negative stiffness, which is inherently nonlinear, creates internal resonance; therefore, the vibration energy can be transmitted from low-frequency to high-frequency vibrating modes, causing vibration suppression. The nonlinear absorber is added to the primary nonlinear system, and when the main system is subjected to external resonance due to harmonic excitation, the negative stiffness parameter of absorber is so adjusted that autoparametric resonance occurs and vibration is reduced. First, the mathematical...
Study on Behavior of Diagonally Stiffened Steel Plate Shear Walls
,
Ph.D. Dissertation
Sharif University of Technology
;
Joghataie, Abdolreza
(Supervisor)
;
Khajeh Ahmad Attari, Nader
(Supervisor)
Abstract
In this study, the behavior of diagonally stiffened steel plate shear wall systems which have a new configuration of stiffeners is investigated. This dissertation is divided into three main sections which contain experimental studies, finite element analysis and developing design equations. In the section on experimental studies, 5 single-bay, single-story, one-third scale specimens were tested. An unstiffened specimen as a control sample and two other specimens with different configuration of stiffeners were constructed and tested to study the effect of diagonal stiffeners. Based on the observations during the tests, it was decided to add and study two other specimens too, including one...
Embedded SI partial transmit sequence with improved bit error rate
, Article 2nd International Conference on Electrical Engineering, ICEE, Lahore, 25 March 2008 through 26 March 2008 ; 2008 ; 9781424422937 (ISBN) ; Ahmadian Attari, M ; Reisi, N
2008
Abstract
OFDM is a multicarrier modulation scheme with high bandwidth efficiency and robustness to multipath environment used in high data rate transmission. However, a drawback of this system is the large Peak-to-Average-Power Ratio (PAR) of the transmit signal which makes its straightforward implementation quite costly. PAR in an OFDM based system can be reduced significantly by PTS method for which data recovery requires side information (SI) about the phases used at transmitter. Sending SI, not only reduces the rate, but also increases BER, for any error in SI detection can damage a large amount of transmitted information. By introducing a new phase set, we propose a PTS based method for MPSK...
Investigation of Texture Effects on the Deformation of Sheet Metals using Crystal Plasticity Theory
, M.Sc. Thesis Sharif University of Technology ; Assempour, Ahmad (Supervisor) ; Mehdigholi, Hamid (Co-Advisor)
Abstract
The orientations which predominate in a final orientation distribution resulted from a specific deformation mode are the ideal orientations. There is a set of ideal orientations for each of crystal structures under a predefined mode of deformation. Ideal orientations are one of the material characteristics in the applied mode of deformation. The material texture strongly influences its final properties and affects the material behaviour in the subsequent forming processes.
In this project, final texture of 1010 steel sheet resulted from simple tension mode of deformation is investigated computationally and experimentally. The calculated texture based on the simulation procedure is...
In this project, final texture of 1010 steel sheet resulted from simple tension mode of deformation is investigated computationally and experimentally. The calculated texture based on the simulation procedure is...
Using the fluid/structure interaction to mitigate the seismic response of structures equiped with cylindrical liquid tanks subjected to near field earthquakes
, Article 11th East Asia-Pacific Conference on Structural Engineering and Construction, EASEC-11, Taipei, 19 November 2008 through 21 November 2008 ; 2008 ; Rofooei, F. R ; Sharif University of Technology
2008
Abstract
Seismic response of a Single Degree of Freedom (SDOF) system containing a rigid circular cylindrical liquid tank under the earthquake excitations is considered in the presence of fluid/structure interaction. The governing differential equations of the system is derived considering the first three liquid sloshing modes (1, 1), (0, 1) and (2, 1) under different strong ground motions. The dynamic response of the system is investigated in the neighborhood of 1:1 and 1:2 internal resonances between the SDOF system and the liquid sloshing modes. These internal resonances take place by tuning the frequency of the first asymmetric sloshing mode of the liquid to the fundamental frequency of the SDOF...
Investigation of CFS shear walls with one and two-sided steel sheeting
, Article Journal of Constructional Steel Research ; Volume 122 , 2016 , Pages 292-307 ; 0143974X (ISSN) ; Alizadeh, S ; Hadidi, S ; Sharif University of Technology
Elsevier Ltd
2016
Abstract
In this study six Cold-Formed Steel shear wall (CFS) with one and two side steel sheeting are tested under reversed cyclic loading. Besides, thirteen numerical models are simulated, using nonlinear finite element method, and analyzed under monotonic pushover loading. The studied parameters are the comparison of one and two side steel sheeting, the nominal thickness of steel sheet and boundary elements, and height to width aspect ratios of the wall. The performance of tested specimens is investigated in terms of lateral load-story drift response, failure modes and ultimate strength of shear walls. Based on AISI S213 the available strength of two-sided steel-sheathed walls is cumulative but...
Adsorption of TiO2 nanoparticles on glass fibers
, Article Journal of Physical Chemistry C ; Volume 111, Issue 27 , 2007 , Pages 9794-9798 ; 19327447 (ISSN) ; Taghavinia, N ; Irajizad, A ; Mahdavi, M ; Sharif University of Technology
2007
Abstract
Titania was deposited on glass fibers with a partial epoxy layer coating from a solution containing TiO2 nanoparticles at T = 90°C, and the adsorption process was examined by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), Fourier transform infrared (FT-IR) spectroscopy, and photocatalytic activity measurements. XPS data demonstrated that about 25% of the surface was covered with TiO2 nanoparticles, with 10% on the epoxy layer and 15% on the glass body. It was found that TiO2 nanoparticles can be readily adsorbed on epoxy groups, whereas they have a low tendency to adsorb on carbon polymer chains. This difference can be...
Modal spectra combination method for pushover analysis of special steel moment resisting frames
, Article International Journal of Civil Engineering ; Volume 10, Issue 4 , 2012 , Pages 245-252 ; 17350522 (ISSN) ; Mirjalili, M. R ; Attari, N. K. A ; Sharif University of Technology
2012
Abstract
The nonlinear static procedures (NSPs) proposed by design codes do not lead to reliable results especially for tall buildings. They generally provide inconsistent estimates of inelastic seismic demands, especially for the top floors due to their inabilities in considering the higher modes effects. In this paper, a new enhanced pushover procedure is proposed which is based on the envelope of the structural responses resulting from two separate pushover analyses as a combination rule. Also, the suggested pushover analyses are performed using a newly proposed modal load pattern, i.e., the Modal Spectra Combination (MSC), and the ASCE41-06 required first mode load pattern. The MSC load pattern...