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Investigation of various concrete materials to simulate seismic response of RC structures
, Article Structures ; Volume 29 , 2021 , Pages 1322-1351 ; 23520124 (ISSN) ; Gharavi, A ; Epackachi, S ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
This paper focuses on the performance evaluation of several concrete models in reinforced concrete (RC) structures subjected to seismic loading. Despite many studies conducted on implementing different characteristics of concrete in constitutive models, there is an essential need for investigating the ability of these models in predicting the behavior of structures in seismic applications. In this paper, several developed plasticity-based constitutive models with the combination of fracture and continuum damage models are investigated for application in seismic loading conditions. Damage-based isotropic and anisotropic models and smeared cracking approach have been applied as complementary...
Numerical study on split base plate connection with concentric anchors between steel-plate composite wall and concrete basemat
, Article Structural Design of Tall and Special Buildings ; Volume 31, Issue 11 , 2022 ; 15417794 (ISSN) ; Mirghaderi, S. R ; Epackachi, S ; Asgarpoor, M ; Gharavi, A ; Sharif University of Technology
John Wiley and Sons Ltd
2022
Abstract
Steel-plate composite (SC) walls can be connected to a concrete basemat using a base plate and a set of anchors eccentric to the wall. The base plate can be separated into two parts so that the concrete of the wall and basemat is cohesive, and thus, the wall can be manufactured more easily and economically. Additionally, compression and shear demand are directly transferred from infill concrete to concrete basemat. Another change in the base plate connection of available tested walls involves transferring anchors to the bottom of faceplates. As a result of this modification, the base plate is removed from the force transmission chain, and the force is transferred directly from the wall to...
Finite element analysis of rectangular and flanged steel-concrete shear walls under cyclic loading
, Article Structural Design of Tall and Special Buildings ; Volume 30, Issue 12 , 2021 ; 15417794 (ISSN) ; Gharavi, A ; Epackachi, S ; Mirghaderi, S.R ; Sharif University of Technology
John Wiley and Sons Ltd
2021
Abstract
The seismic performance of steel-plate concrete (SC) shear walls is numerically investigated for various SC wall geometrical shapes. Steel faceplates and infill concrete are two main components of SC walls; a full connection between steel and concrete is required for composite action. A comprehensive set of SC wall specimens with different cross-sectional shapes and geometrical properties were tested in the literature for evaluating their seismic behavior. The numerical responses of 17 tested SC walls, including rectangular, T-shaped, and flanged walls, isolated and coupled walls, with and without boundary elements and endplates, subjected to cyclic lateral loading and a wide range of axial...
Nonlinear modeling for composite plate shear walls-concrete filled structures
, Article Journal of Building Engineering ; Volume 63 , 2023 ; 23527102 (ISSN) ; Gharavi, A ; Epackachi, S ; Imanpour, A ; Sharif University of Technology
Elsevier Ltd
2023
Abstract
This paper proposes modeling recommendations, including constitutive model parameters for concrete and steel for nonlinear and macroscopic simulation of Composite Plate Shear Walls-Concrete Filled (C-PSW/CF) structures. Predictive equations are developed to determine the constitutive models of confined and unconfined concrete and steel faceplates, considering the buckling and fracture effects. A comprehensive database consisting of the test results of 37 C-PSW/CF specimens with and without endplates and boundary elements is collected and used to assess the required constitutive model parameters. Based on the validated macro model, predictive equations for backbone curves of unconfined and...
Influence of Soil-Structure Interaction on Collapse Margin Ratio
, M.Sc. Thesis Sharif University of Technology ; Ghannad, Mohammad Ali (Supervisor)
Abstract
This thesis reveals the influence of soil-structure interaction (SSI) on the collapse potential of structures and also investigates the change in collapse margin ratio (CMR) of structures for which the design base shear has been reduced based on the soil-structure interaction provisions. According to the properties of structures and seismic excitations, SSI can increase, decrease or make no change in the response of structures. Based on seismic design codes for fixed-base structures, SSI causes reduction in design base shear of buildings. These provisions are based on linear behavior of structures. But under strong ground motions, specially at collapse level, structures can experience strong...
Numerical evaluation of the cyclic response parameters of steel–concrete composite shear
, Article Lecture Notes in Civil Engineering ; Volume 348 LNCE , 2023 , Pages 811-818 ; 23662557 (ISSN); 978-303134158-8 (ISBN) ; Gharavi, A ; Epackachi, S ; Imanpour, A ; Gupta R ; Sun M ; Brzev S ; Alam M. S ; Ng K. T ; Li J ; El Damatty A ; Lim C ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2023
Abstract
Steel–concrete (SC) composite shear walls consist of infill concrete attached to two steel faceplates using tie rods and shear studs as connectors. Despite past efforts to validate the cyclic response of SC walls numerically, there is a lack of a comprehensive numerical study to propose a unique element modeling, steel and concrete material modeling, and contact definition to simulate the seismic response of all SC walls with different geometrical shapes and loading condition accurately. This paper numerically investigates the response of a wide variety of tested SC walls available in the literature. Ten SC wall specimens are modeled in the finite element-based software LS-DYNA and subjected...
Macro modeling of steel-plate concrete composite shear walls in the opensees environment
, Article Lecture Notes in Civil Engineering ; Volume 348 LNCE , 2023 , Pages 537-545 ; 23662557 (ISSN); 978-303134158-8 (ISBN) ; Gharavi, A ; Epackachi, S ; Imanpour, A ; Gupta R ; Sun M ; Brzev S ; Alam M. S ; Ng K. T ; Li J ; El Damatty A ; Lim C ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2023
Abstract
A new macro model is developed in the OpenSees environment to analyze SC shear walls efficiently. The proposed modeling technique benefits from higher accuracy in predicting the response of SC walls compared to similar macro models and lower computational costs. The proposed model is then used to predict the cyclic response of 12 rectangular SC wall specimens with and without boundary elements and end plates, tested under cyclic loading. The results confirm that the initial stiffness, peak strength, displacement at peak strength, and post-peak behavior predicted are in good agreement with test results. © 2023, Canadian Society for Civil Engineering
Probability of missed detection as a criterion for receiver placement in MIMO PCL
, Article IEEE National Radar Conference - Proceedings, 7 May 2012 through 11 May 2012, Atlanta, GA ; 2012 , Pages 0924-0927 ; 10975659 (ISSN) ; 9781467306584 (ISBN) ; Chitgarha, M. M ; Radmard, M ; Nayebi, M. M ; Sharif University of Technology
IEEE
2012
Abstract
Using multiple antennas at the transmit and receive sides of a passive radar brings both the benefits of MIMO radar and passive radar. However one of the obstacles arisen in such configuration is the receive antennas placement in proper positions so that the radar performance is improved. Here we just consider the case of positioning one receiver among multiple illuminators of opportunity. Indeed it is a start for the solution of optimizing the geometry of the multiple receivers in a passive radar
An efficient method for the ring opening of epoxides with aromatic amines by Sb(III) chloride under microwave irradiation
, Article Journal of Chemical Research ; Issue 4 , 2008 , Pages 220-221 ; 03082342 (ISSN) ; Hashemi, M. M ; Mottaghi, M. M ; Foroughi, M. M ; Sharif University of Technology
2008
Abstract
SbCl3 supported on montmorillonite K-10 is an efficient catalyst for the ring opening of epoxides with aromatic amines under solvent-free conditions and microwave irradiation to give the corresponding b-amino alcohols in high yields with high regioselectivity
Resource allocation for uav-enabled integrated sensing and communication (isac) via multi-objective optimization
, Article ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings ; Volume 2023-June , 2023 ; 15206149 (ISSN); 978-172816327-7 (ISBN) ; Naghsh, M. M ; Karbasi, M ; Nayebi, M. M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2023
Abstract
In this paper, we consider an integrated sensing and communication (ISAC) system with wireless power transfer (WPT) where an unmanned aerial vehicle (UAV)-based radar serves a group of energy-limited communication users in addition to its sensing functionality. In this architecture, the radar senses the environment in phase 1 (namely sensing phase) and mean-while, the communications users (nodes) harvest and store the energy from the radar transmit signal. The stored energy is then used for information transmission from the nodes to UAV in phase 2, i.e., uplink phase. Performance of the radar system depends on the transmit signal as well as the receive filter; the energy of the transmit...
MIMO radar signal design to improve the MIMO ambiguity function via maximizing its peak
, Article Signal Processing ; Volume 118 , 2016 , Pages 139-152 ; 01651684 (ISSN) ; Radmard, M ; Nazari Majd, M ; Karbasi, S. M ; Nayebi, M. M ; Sharif University of Technology
Elsevier
2016
Abstract
One of the important obstacles in MIMO (Multiple Input Multiple Output) radars is the issue of designing proper transmit signals. Indeed, the capability of signal design is a significant advantage in MIMO radars, through which, the system can achieve much better performance. Many different aspects of this performance improvement have been considered yet, and the transmit signals have been designed to attain such goal, e.g., getting higher SNR or better detector's performance at the receiver. However, an important tool for evaluating the radar's performance is its ambiguity function. In this paper, we consider the problem of transmit signal design, in order to optimize the ambiguity function...
Detection-localization tradeoff in MIMO radars
, Article Radioengineering ; Volume 26, Issue 2 , 2017 , Pages 581-587 ; 12102512 (ISSN) ; Radmard, M ; Chitgarha, M. M ; Bastani, M. H ; Nayebi, M. M ; Sharif University of Technology
2017
Abstract
Two gains play key roles in recently developed MIMO wireless communication systems: "spatial diversity" gain and "spatial multiplexing" gain. The diversity gain refers to the capability to decrease the error rate of the MIMO channel, while the multiplexing gain implicitly refers to the amount of increase in the capacity of the MIMO channel. It has been shown that there is a fundamental tradeoff between these two types of gains, meaning interplay between increasing reliability (via an increase in the diversity gain) and increasing data rate (via an increase in the multiplexing gain). On the other hand, recently, MIMO radars have attracted much attention for their superior ability to enhance...
Antenna placement and power allocation optimization in MIMO detection
, Article IEEE Transactions on Aerospace and Electronic Systems ; Vol. 50, Issue 2 , April , 2014 , pp. 1468-1478 ; Chitgarha, M. M ; Majd, M. N ; Nayebi, M. M ; Sharif University of Technology
2014
Abstract
It is a well known fact that using multiple antennas at transmit and receive sides improves the detection performance. However, in such multiple-input multiple-output (MIMO) configuration, proper positioning of transmitters and receivers is a big challenge that can have significant influence on the performance of the overall system. In addition, determining the power of each transmitter under a total power constraint is a problem that should be solved in order to enhance the performance and coverage of such a system. In this paper, we design the Neyman-Pearson detector under the Rayleigh scatter model and use it to introduce a criterion for the antenna placement at both transmit and receive...
Ambiguity function of MIMO radar with widely separated antennas
, Article Proceedings International Radar Symposium ; 16 -18 June , 2014 ; ISSN: 21555753 ; Chitgarha, M. M ; Nazari Majd, M ; Nayebi, M. M ; Sharif University of Technology
2014
Abstract
There has been much interest, recently, towards exploiting the Multiple-Input Multiple-Output (MIMO) technique in radar. It is shown that using multiple antennas at transmit and receive sides can improve the performance of the system. However, in order to analyze the system's performance, its ambiguity function, i.e. the ambiguity function of a MIMO radar, is needed to be defined. In this paper, beginning from the information theoretic definitions, we derive such function, specifically for a MIMO radar with widely separated antennas
Choosing the position of the receiver in a MISO passive radar system
, Article European Microwave Week 2012: "Space for Microwaves", EuMW 2012, Conference Proceedings - 9th European Radar Conference, EuRAD 2012 ; 2012 , Pages 318-321 ; 9782874870293 (ISBN) ; Majd, M. N ; Radmard, M ; Nayebi, M. M ; Sharif University of Technology
2012
Abstract
By combining the two ideas of MIMO (Multiple Input Multiple Output) and PCL (Passive Coherent Location) in radar, one can achieve the advantages of both recently developed techniques simultaneously. While using multiple antennas at the receive side provides a spatial diversity of the object to be detected, using multiple illuminators of opportunity, most importantly, makes the radar covert to the interceptors. One obstacle in such MIMO configuration is choosing the positions of the receive antennas. In this paper, after analyzing the Neyman-Pearson detector for the DVB-T based PCL, we introduce the probability of missed detection as a criterion to place the receive antenna. Here, we only...
Adaptive filtering techniques in passive radar
, Article Proceedings International Radar Symposium, Dresden ; Volume 2 , June , 2013 , Pages 1067-1078 ; 21555753 (ISSN) ; 9783954042234 (ISBN) ; Radmard, M ; Majd, M. N ; Nayebi, M. M ; Sharif University of Technology
2013
Abstract
One of the most important obstacles in passive radar applications is removing the direct signal from the target channel. Otherwise, week echoes from the targets in the target channel would be ignored due to the limited dynamic range of the system. One of the most effective techniques in this field is using adaptive filters. In this paper various adaptive filters are introduced and their performances are shown and compared
Ambiguity function based receiver placement in multi-site radar
, Article 2016 CIE International Conference on Radar, RADAR 2016, 10 October 2016 through 13 October 2016 ; 2017 ; 9781509048281 (ISBN) ; Chitgarha, M. M ; Nazari Majd, M ; Nayebi, M. M ; Sharif University of Technology
2017
Abstract
It has been shown that using multiple antennas in a radar system improves the performance considerably, since multiple target echoes are received from different aspect angles of the target. In this way, the target detection is improved. However, when using multiple antennas, some problems, such as designing the transmit signals, synchronization, etc. emerge that should be solved. One of such problems is the receiver placement. Receiver placement deals with choosing a proper position for the receive antenna in order to optimize the whole system's performance. In this paper, a receiver placement procedure based on improving the radar ambiguity function is proposed for the case of a multisite...
Improving MIMO radar's performance through receivers' positioning
, Article IET Signal Processing ; Volume 11, Issue 5 , 2017 , Pages 622-630 ; 17519675 (ISSN) ; Radmard, M ; Nazari Majd, M ; Nayebi, M. M ; Sharif University of Technology
Institution of Engineering and Technology
2017
Abstract
By employing the MIMO (multiple-input-multiple-output) technology in radar, some new problems emerged, that, in order to benefit the MIMO gains in radar, it was necessary to solve them suitably. One of such obstacles is determining the positions of receive antennas in a MIMO radar system with widely separated antennas (WS MIMO radar), since it is shown that the antennas' positions affect the whole system's performance considerably. In this study, a proper receivers' positioning procedure is proposed. To do this end, four criteria are developed based on the proposed MIMO detector and the MIMO ambiguity function. The simulations verify that the proposed positioning procedure improves the...
Silylation of hydroxy groups with HMDS under microwave irradiation and solvent-free conditions
, Article Phosphorus, Sulfur and Silicon and Related Elements ; Volume 177, Issue 2 , 2002 , Pages 289-292 ; 10426507 (ISSN) ; Saidi, M. R ; Bolourtchian, M ; Heravi, M. M ; Sharif University of Technology
2002
Abstract
Phenols and alcohols are silylated with hexamethyldisilazane (HMDS) under microwave irradiation in solvent-free condition in good to excellent yields
An intelligent solvent selection approach in carbon capturing process: a comparative study of machine learning multi-class classification models
, Article Results in Engineering ; Volume 23 , 2024 ; 25901230 (ISSN) ; Hosseinpour, M ; Salimi, M ; Boroushaki, M ; Amidpour, M ; Sharif University of Technology
2024
Abstract
Carbon capture is crucial for mitigating climate change and achieving global emissions reduction targets. Among various technologies, absorption-based methods using aqueous solvents are among the most common and efficient, offering high capture rates and retrofit capabilities for existing industrial facilities. However, selecting the optimal solvent is challenging due to its direct impact on the performance, efficiency, and cost-effectiveness of the carbon capture process. This research introduces a novel multi-class classification methodology for solvent selection in carbon capture. Leveraging a dataset of 656 data points, including features such as temperature, pressure, molar ratio, and...