Response modification factor of dual moment-resistant frame with buckling restrained brace (BRB)

Abdollahzadeh, Gholamreza,Mohammadreza Banihashemi 국제구조공학회 2013 Steel and Composite Structures, An International J Vol.14 No.6

Response modification factor is one of the seismic design parameters to consider nonlinear performance of building structures during strong earthquake, in conformity with the point that many seismic design codes led to reduce the loads. In the present paper it's tried to evaluate the response modification factors of dual moment resistant frame with buckling restrained braced (BRB). Since, the response modification factor depends on ductility and overstrength; the nonlinear static analysis, nonlinear dynamic analysis and linear dynamic analysis have been done on building models including multi-floors and different brace configurations (chevron V, invert V, diagonal and X bracing). The response modification factor for each of the BRBF dual systems has been determined separately, and the tentative value of 10.47 has been suggested for allowable stress design method. It is also included that the ductility, overstrength and response modification factors for all of the models were decreased when the height of the building was increased.

On the conjecture of planar graphs

Abdollahzadeh Ahangar,Pushpalatha 장전수학회 2010 Advanced Studies in Contemporary Mathematics Vol.20 No.1

Let G be a graph. Suppose that for each vertex v in G, there exists a list of k colors, L(v), such that there is a unique proper coloring for G from this collection of lists. Then G is called a uniquely k-list colorable graph. In this note we disprove a Conjecture for U3LC planar graphs which appeared in [3].

Effects of thermal boundary conditions on the joule heating of electrolyte in a microchannel

Abdollahzadeh Jamalabadi, M. Y.,Park, J. H.,Rashidi, M. M.,Chen, J. M. Springer-Verlag 2016 Journal of hydrodynamics. Ser. B Vol.28 No.5

<P>Joule heating effects on a slit microchannel filled with electrolytes are comprehensively investigated with emphasis on the thermal boundary conditions. An accurate analytical expression is proposed for the electrical field and the temperature distributions due to Joule heating are numerically obtained from the energy balance equation. The results show that a thermal design based on the average electric potential difference between electrodes can cause severe underestimation of Joule heating. In addition, the parametric study of thermal boundary conditions gives us an insight into the best cooling scenario for microfluidic devices. Other significant thermal characteristics, including Nusselt number, thermophoretic force, and entropy generation, are discussed as well. This study will provide useful information for the optimization of a bioMEMS device in relation to the thermal aspect.</P>

Numerical analysis of natural convection of magnetohydrodynamic flow in vertical micro-channel with rarefaction effects and radiative heat transfer

Abdollahzadeh Jamalabadi, Mohammad Yaghoub,Kim, Se Won,Lee, Chang Yeop,Park, Jae Hyun SAGE Publications 2016 Advances in mechanical engineering Vol.8 No.4

Un-met Supportive Care Needs of Iranian Breast Cancer Patients

Abdollahzadeh, Farahnaz,Moradi, Narges,Pakpour, Vahid,Rahmani, Azad,Zamanzadeh, Vahid,Mohammadpoorasl, Asghar,Howard, Fuchsia Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.9

Background: Assessment of supportive needs is the requirement to plan any supportive care program for cancer patients. There is no evidence about supportive care needs of Iranian breast cancer patients. So, the aims of present study were to investigate this question and s predictive factors. Materials and Methods: A descriptive-correlational study was conducted, followed by logistic regression analyses. The Supportive Care Needs Survey was completed by 136 breast cancer patients residing in Iran following their initial treatment. This assessed needs in five domains: psychological, health system and information, physical and daily living, patient care and support, and sexuality. Results: Patient perceived needs were highest in the health systems and information (71%), and physical and daily living (68%) domains. Logistic regression modeling revealed that younger participants have more un-met needs in all domains and those with more children reported fewer un-met needs in patient care and support domains. In addition, married women had more un-met supportive care needs related to sexuality. Conclusions: The high rate of un-met supportive care needs in all domains suggests that supportive care services are desperately required for breast cancer patients in Iran. Moreover, services that address informational needs and physical and daily living needs ought to be the priority, with particular attention paid to younger women. Further research is clearly needed to fully understand supportive care needs in this cultural context.

Response modification factor of suspended zipper braced frames

Gholamreza Abdollahzadeh,Mehdi Abbasi 국제구조공학회 2015 Steel and Composite Structures, An International J Vol.18 No.1

The suspended zipper bracing system is suggested to reduce the flaws of ordinary zipper braced and concentric inverted V braced frames. In the design procedure of suspended zipper bracing systems, columns and top story truss elements are strengthened. This bracing system show different performances and characteristics compared with inverted V braced and ordinary zipper frames. As a result, a different response modification factor for suspend zipper frames is needed. In this research paper, the response modification factor of suspended zipper frames was obtained using the incremental dynamic analysis. Suspended zipper braced frames with different stories and bay lengths were selected to be representations of the design space. To analyze the frames, a number of models were constructed and calibrated using experimental data. These archetype models were subjected to 44 earthquake records of the FEMA-P695 project data set. The incremental dynamic analysis and elastic dynamic analysis were carried out to determine the yield base shear value and elastic base shear value of archetype models using the OpenSEES software. The seismic response modification factor for each frame was calculated separately and the values of 9.5 and 13.6 were recommended for ultimate limit state and allowable stress design methods, respectively.

Retrofitting of Steel Moment-Resisting Frames under Fire Loading against Progressive Collapse

Gholamreza Abdollahzadeh,Reza Shalikar 한국강구조학회 2017 International Journal of Steel Structures Vol.17 No.4

Generally, fire has been one of the most important threats which can lead to the collapse of structures. Due to the high temperature caused by fire, material strength decrease significantly and finally, could lead to failure of different members of a structure. When some parts of the structure are damaged, frames without sufficient resistance and ductility can progressively collapse. In this study, the retrofitting effect of a Steel Moment-Resisting Frame (MRFs) with X and inverted-V braces are investigated using dynamic explicit analysis for frames which had previously suffer progressive collapse under fire. Simultaneously, different bracing systems and fire conditions have been used. Furthermore, the effect of stiffness and strength of bracing systems were numerically analyzed. Studies show that the unbraced moment-resisting frame (MRF) lacks an effective mechanism for transferring loads from failed parts to the neighboring parts and the frame completely collapse due to the catenary actions under fire loading in central span. Systems braced with hat truss, due to their distance from the heated columns, have limited capacity to prevent the pull-in of columns in the heated floor. However, they can directly re-distribute vertical loads which are shed by buckled columns to the neighboring columns. But, their performance in central span fire scenario seems relatively better than edge span fire scenario. On the other hand, vertical bracing systems have a good effect and with restraining the columns, it can prevent them from pull-in. Also, they are able to effectively prevent the global collapse process. Furthermore, the stronger vertical bracing system can decrease the vertical movement of the heated columns and thus, enhance the re-distribution capacity of the frame. Accordingly, with combination of hat truss bracing system and vertical bracing system, new paths can be generated for redistribution of the forces which are shed by failed columns in the frame. At the end, comparing between X bracing systems and inverted-V bracing systems indicates that the frames with inverted-V bracing systems show more ductility.

On uniquely 3-list colorable graphs

H. Abdollahzadeh Ahangar,L. Pushpalatha,S.M. Sheikholeslami,Yancai Zhao 장전수학회 2012 Advanced Studies in Contemporary Mathematics Vol.22 No.4

Let G be a graph with n vertices and suppose that for each vertex v in G,there exists a list of at least k colors, L(v), such that there is a unique proper coloring for G from this collection of lists, then G is called a uniquely k-list colorable graph. The minimum k for which G is not uniquely k-list colorable is called the m-number of G. In this paper, we study the uniquely 3-list colorable graphs.

Proposing a Method for Robustness Index Evaluation of the Structures Based on the Risk Analysis of Main Shock and Aftershock

Gholamreza Abdollahzadeh,Hadi Faghihmaleki 한국강구조학회 2018 International Journal of Steel Structures Vol.18 No.5

Investigating remained damages from terrible earthquakes, it could be concluded that some events including explosion because of defect and failure in the building mechanical facilities or caused by gas leak, fi ring, aftershocks, etc., which are occurred during or a few time after the earthquake, will increase the eff ects of damages. In this paper, by introducing a complete risk analysis which included direct and indirect risks for earthquake (the main shock) and aftershock, the corresponding robustness index was created that called as “robustness index sequential critical events risk-based”. One of the main properties of the intended robustness index is using progressive collapse percentage in its evaluation. Then, in a numerical example for a 4-storey moment resisting steel frame structure, a method is presented for obtaining all eff ective parameters in robustness index evaluation based on the intended risk and at last its results were reported.

Cyclic behavior of DCFP isolators with elliptical surfaces and different frictions

Gholamreza Abdollahzadeh,Reza Darvishi 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.64 No.6

Friction Pendulum isolators are tools developed in the past few decades. The simplest form of these isolators, are FPS whose main disadvantages are having a constant frequency independent of the frequency of the structure. For this reason, researchers have invented VFPI isolator whose frequency is variable and depends on displacement. Another friction pendulum isolator is DCFP isolator which is a combination of two FPS isolators. In this article, first by changing the geometry of DCFP isolator plates from spherical to elliptical, the motion and frequency equations of DVFPI isolators are defined, and then the seismic behavior of DVFPI isolators are analyzed in various geometric and plate friction settings using motion equations, and confirmed using ABAQUS software. The most important results of this study are that the hysteresis behavior of DVFPI isolators are severely nonlinear, its curve follows two distinct curvatures, and that the restoring force is faced with softening mechanism that limits the seismic force transmitted to the structure, whereas the restoring force in DCFP isolators increases linearly with increasing displacement.