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Article 16th International Conference of the International Association for Computer Methods and Advances in Geomechanics, IACMAG 2021, 5 May 2021 through 8 May 2021 ; Volume 126 , 2021 , Pages 326-333 ; 23662557 (ISSN); 9783030645175 (ISBN) ; Toufigh, V ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH 2021
This paper presents an experimental study on the interfacial characteristics of rammed earth materials stabilized with the combination of cement and alkali-activated fly ash (AAFA), an eco-friendly alternative for cement. Several direct shear tests were conducted to obtain cohesion and friction angle to do so. Moreover, pulse velocity and unconfined compression tests were exploited to assess other physical and mechanical properties of this material. Through the methodology used in this work, it is shown that the replacement of cement with AAFA dramatically improved cohesion, compressive strength, and pulse velocity. However, no general correlation was observed for the friction angle. © 2021,...
Article Structural Concrete ; 2021 ; 14644177 (ISSN) ; Toufigh, V ; Sharif University of Technology
John Wiley and Sons Inc 2021
In this article, the self-compacting lightweight concretes (SCLC) with different fibers were prepared and exposed to elevated temperatures, and their mechanical properties were investigated. Three types of fibers were steel fibers (SF), polypropylene fibers (PPF), and metal springs with a volume fraction of 0.4%. One hundred and fifty cylindrical specimens were prepared, and the compression, tensile and flexural tests were carried out on them after exposure to high temperatures ranging from 25 to 700°C. The findings indicate that incorporation of steel fibers and springs enhanced the compressive strength of concrete by 20% compared to the control specimen. Meanwhile, the polypropylene fibers...
Application of ultrasonic models for investigating the properties of the interface between roller compacted concrete (RCC) layers, Article NDT and E International ; Volume 124 , 2021 ; 09638695 (ISSN) ; Toufigh, V ; Ghaemian, M ; Azizmohammadi, M ; Sharif University of Technology
Elsevier Ltd 2021
In this paper, a comprehensive set of linear and nonlinear ultrasonic techniques was performed to investigate the properties of the interface between the roller-compacted concrete (RCC) layers. The effect of different time intervals between the pouring of each layer, cement content of concrete and bedding mortar, and various curing periods on RCC specimens were studied in this research. In linear methods, the interlayer led to velocity dispersion and attenuation phenomena except for the inherent inhomogeneity of specimens. The nonlinear parameters showed a general upward at the earlier ages, while the linear methods did not show an apparent regularity. The ultimate strength results were then...
Numerical and experimental investigation on a BRB confined with partially carbon fiber reinforced polymer (CFRP), Article Engineering Structures ; Volume 223 , 2020 ; Toufigh, V ; Sharif University of Technology
Elsevier Ltd 2020
Buckling-restrained braces (BRBs) have been spread widely, especially in high seismic hazard zones due to their excellent energy absorption capacity. BRBs are composed of a main load-carrying steel core restrained with other elements mostly made of concrete and steel casing to preserve it from buckling. Although BRBs provide excellent cyclic behavior, a problem is with their heaviness, which leads to difficulties such as installation and transportation. This study presents a numerical and experimental investigation on a BRB with a new proposed restraining system composed of concrete panels confined with partially carbon fiber reinforced polymer (CFRP) strips to reduce the weight of the...
Fatigue performance of polymer and ordinary cement concrete under corrosive conditions: A comparative study, Article Engineering Failure Analysis ; Volume 111 , 2020 ; Rajabi, H ; Toufigh, V ; Sharif University of Technology
Elsevier Ltd 2020
Many concrete structures such as bridges, offshore structures, and pavements are under cyclic loads when they are exposed to different environmental conditions during their lifespan. The durability and fatigue performance of these structures are significant issues that should be considered. Therefore, this study investigated the long-term environmental effects on Polymer Concrete (PC) and Ordinary Cement Concrete (OCC) subjected to cyclic fatigue loading under four different environmental conditions (freshwater, seawater, acidic and alkaline) for six months. Concrete specimens are tested under high cyclic loading with the frequency of 6 Hz and low cyclic loading with a frequency of 1 Hz....
Article Construction and Building Materials ; Volume 234 , 2020 ; Toufigh, V ; Sharif University of Technology
Elsevier Ltd 2020
Polymer concrete is well-known for quick repairing of concrete structures and pavement. However, there are relatively few studies on the durability of epoxy polymer concrete (EPC). This study aims to investigate the long-term environmental effects on the mechanical properties of EPC. Therefore, EPC and ordinary cement concrete (OCC) specimens were prepared and exposed to four chemical solutions with pH values of 2.5, 7, 12.5 and artificial seawater in intervals of 1, 3, 6, 9 and 12 months. Epoxy resin (10 and 12% by weight) and Portland cement were used as binder phase in EPC and OCC specimens, respectively. Scanning electron microscopy (SEM) was additionally applied to investigate the...
Article Journal of Cleaner Production ; Volume 277 , December , 2020 ; Toufigh, V ; Sharif University of Technology
Elsevier Ltd 2020
Rammed earth (RE) is an eco-friendly building material and has been capturing special attention among researchers. Many of the recently studied RE additives are extremely resource- and energy-consuming. On the other hand, the usage of fly ash (FA), which is a sustainable replacement for cement, has been scarcely investigated in RE construction. In this paper, an experimental investigation was performed on the physical and mechanical properties of RE materials stabilized with the combination of cement and alkali-activated FA. This scrutiny consists of density measurements, pulse velocity tests, unconfined compression tests, and direct shear tests. Additionally, the carbon dioxide emission and...
Article European Journal of Environmental and Civil Engineering ; 2020 ; Toufigh, V ; Sharif University of Technology
Taylor and Francis Ltd 2020
This study explores the effect of Guar gum as an eco-friendly additive on concrete mechanical characteristics. In the first stage, the slump and relative humidity tests were carried out for the fresh mortar, and tensile and compressive strengths were then determined for fifteen different mixture designs with two different curing times. Further, an exponential correlation was obtained between the ultrasonic pulse velocity and the compression test results. Additionally, scanning electron microscope (SEM) was employed to assess the bond between aggregates and Guar gum. At last, the Taguchi method and ANOVA were utilized to conduct the optimum states of the mechanical characteristics of the...
Article Geotechnical and Geological Engineering ; Volume 38, Issue 2 , 2020 , Pages 1949-1969 ; Toufigh, V ; Ghaemian, M ; Sharif University of Technology
The interface behavior of rock and concrete and between layers of concrete highly affects the performance of concrete dam structures. In this investigation, a modified direct shear test was implemented in the laboratory to evaluate the interface behavior between (1) rock and conventional vibrated concrete (CVC), (2) rock and roller compacted concrete (RCC), (3) CVC and RCC and (4) two layers of RCC. Series of in situ shear tests were also performed between rock and concrete. The friction angle and cohesion for all tested interface were determined and analyzed. The effect of uniaxial compressive strength (UCS) of concrete on the interface behavior was determined. Additionally, the effect of...
Assessment of plain and glass fiber-reinforced concrete under impact loading: a new approach via ultrasound evaluation, Article Journal of Nondestructive Evaluation ; Volume 38, Issue 4 , 2019 ; 01959298 (ISSN) ; Toufigh, V ; Sharif University of Technology
Impact loading leads to micro-crack formation that can compromise the performance of the concrete. The purpose of this paper is to evaluate plain concrete and fiber-reinforced concrete specimens using ultrasound methods under impact loading. These specimens were prepared and subjected to impact loading. Ultrasound tests were performed at different stages of impact loading on each specimen. The loading continued until cracks on the surface of the specimens were observed. Investigations were performed for both plain concrete and fiber-reinforced concrete to establish a correlation between ultrasound response characteristics, and the damage caused by impact loading due to the energy of blows...
Article Journal of Earthquake Engineering ; Volume 23, Issue 8 , 2019 , Pages 1297-1317 ; 13632469 (ISSN) ; Toufigh, V ; Golafshani, A. A ; Arzeytoon, A ; Sharif University of Technology
Taylor and Francis Ltd 2019
This study presents the experimental investigation of half-scale, one-story, one-bay pinned frames equipped with a ribbed bracing system (RBS). The RBS is a newly developed passive control system designed to eliminate buckling and enhance the seismic behavior of structures. Here, mechanical models of this bracing system were designed and constructed. Pinned frames equipped with the RBS were cyclically tested. The hysteretic behavior and energy absorbing capacities of the frames were evaluated. Based on the results, the full plastic capacity of the brace was achieved and no buckling occurred. The RBS frame illustrated proper hysteretic behavior and energy dissipation capacity up to 4% story...
Article Journal of Testing and Evaluation ; Volume 49, Issue 3 , 2019 ; 00903973 (ISSN) ; Toufigh, V ; Ghaemian, M ; Sharif University of Technology
ASTM International 2019
The permeability of roller-compacted concrete (RCC) substantially affects its functionality and safety. This study investigates the effect of mix design parameters on the performance of RCC. For this purpose, approximately 500 laboratory specimens were prepared and tested. A formula and an artificial neural network (ANN) were proposed to predict the permeability coefficient of RCC by considering the main parameters, which were then verified independently using new specimens. Furthermore, the experimental data were analyzed by the Taguchi method and analysis of variance (ANOVA) to evaluate the level of parameter contribution. Based on the results, the permeability coefficient was highly...
Article Mechanics of Advanced Materials and Structures ; Volume 26, Issue 4 , 2019 , Pages 333-340 ; 15376494 (ISSN) ; Toufigh, V ; Saadatmanesh, H ; Ahmari, S ; Kabiri, E ; Sharif University of Technology
Taylor and Francis Inc 2019
This research investigates the flexural behavior of a polymer concrete beam/pile encased with carbon fiber sleeve. The mechanical properties of carbon fiber sleeves in tension and cement and polymer concrete in compression were determined. Polymer concrete beams were tested in flexure to determine the bending moment capacity. Then, the test results were compared to the theoretical model results. Finally, a parametric study was conducted to determine the influence of beam/pile parameters on the capacity of the element. Based on the investigation, carbon fiber sleeve filled with polymer concrete exhibits outstanding structural performance including ductility and bending capacity
Article Construction and Building Materials ; Volume 195 , 2019 , Pages 28-40 ; 09500618 (ISSN) ; Toufigh, V ; Sharif University of Technology
Elsevier Ltd 2019
Usage of masonry system in many regions of the world like the Eastern Mediterranean, the Middle East, India, and China is still significantly high, despite their highly energy and intensive emission. Most of the failures in this system are caused by low ductility of cement mortars. This type of failure could be seen in masonry structures in areas in east Iran after Kermanshah earthquake in 2017. The present study investigates the shear bond characteristics of structures constructed by masonry using green materials. “Taftan” natural pozzolan and two types of rice husk ash (RHA) were used in mix design of used mortars as green materials. In this investigation, a modified direct shear test...
Article Structural Design of Tall and Special Buildings ; Volume 27, Issue 13 , 2018 ; 15417794 (ISSN) ; Toufigh, V ; Sharif University of Technology
John Wiley and Sons Ltd 2018
Ribbed bracing system (RBS) is an innovative structural system designed to eliminate the buckling of braces and enhance the behavior of structures under seismic loads. In this study, a collaborative performance of 2 RBS devices bracing a frame was assessed numerically and experimentally. In the numerical phase, the collaboration of ribbed braces at various stages of reversal loading was elaborated mathematically and was used for representing the system using finite element modeling. In the next phase, the numerically observed behavior was validated experimentally by conducting cyclic quasistatic tests of the proposed configurations. Two alternative RBS configurations—called completely closed...
Article Journal of Constructional Steel Research ; Volume 148 , 2018 , Pages 326-335 ; 0143974X (ISSN) ; Toufigh, V ; Sharif University of Technology
Elsevier Ltd 2018
This article evaluates the seismic performance of structures equipped with a ribbed bracing system (RBS). RBS uses ribbed faces that freely slide under compression, however, interlock under tensile forces. Two RBS mechanisms; Completely-closed RBS (CC-RBS) and Improved-centering RBS (IC-RBS), were proposed and successfully tested for eliminating compressive buckling of braces. CC-RBS and IC-RBS provide high energy dissipation capacity and small residual story drifts, respectively. Here, these mechanisms were employed for design and modeling of three structures with varying heights. The models were then subjected to incremental dynamic analysis (IDA), and their seismic performance was...
Article Advances in Structural Engineering ; Volume 21, Issue 9 , 2018 , Pages 1349-1360 ; 13694332 (ISSN) ; Fallah, S ; Sahafipourfard, M. A ; Arzeytoon, A ; Toufigh, V ; Sharif University of Technology
SAGE Publications Inc 2018
In this article, the ribbed bracing system is proposed and evaluated through experimental and numerical studies. Ribbed bracing system is composed of a supplemental part with ribbed interfaces that is attached to a brace member and allows for its free length reduction to prevent the development of compressional forces responsible for buckling of the brace. Ribbed bracing system provides two different mechanisms: completely closed ribbed bracing system and improved-centering ribbed bracing system which are validated, in this study, through design, fabrication, and testing of small-scale specimens subjected to cyclic quasi-static loading. As verified by the test results, in improved-centering...
Article Surface and Coatings Technology ; Volume 344 , 25 June , 2018 , Pages 729-741 ; 02578972 (ISSN) ; Toufigh, V ; Mofid, M ; Sharif University of Technology
Elsevier B.V 2018
This research investigated the long-term environmental effects on the bond at the interface between fiber-reinforced polymer (FRP) and a masonry brick. Seven types of FRP fabrics were used and placed on the masonry brick using the wet lay-up technique. Unidirectional and bidirectional fibers made of aramid, carbon, and glass and also combination of these fabrics were used. A total of 525 specimens were exposed to five chemical solutions with pH values of 2.5, 7, 10, 12.5 and substitution sea water for 1, 3, 6, 9 and 12 months. A chamber was also used to simulate the ultraviolent (UV) radiation on the specimens. A series of single-lap shear tests were performed on these specimens to determine...
A simple model for various types of concretes and confinement conditions based on disturbed state concept, Article Scientia Iranica ; Volume 25, Issue 2A , 2018 , Pages 557-564 ; 10263098 (ISSN) ; Toufigh, V ; Sharif University of Technology
Sharif University of Technology 2018
Concrete is widely used for many practices in Civil Engineering. Therefore, an understanding of its behavior helps engineers and researchers to perform more accurate and cost-effective analyses and designs. In this respect, several models have been proposed to predict the behaviors of concrete most of which are satisfactorily accurate. However, by increasing the accuracy of the models, their computational cost increases, too. In this study, a model with the least computational cost is proposed to predict the behaviors of various concretes and confinement conditions. This model does not require any experimental tests to determine its parameters. It was proved to be able to predict the...
A plasticity-based constitutive model for the behavior of soil-structure interfaces under cyclic loading, Article Transportation Geotechnics ; Volume 14 , 2018 , Pages 41-51 ; 22143912 (ISSN) ; Toufigh, V ; Sharif University of Technology
Elsevier Ltd 2018
In this study, a new plasticity-based constitutive model is proposed for the behavior of soil-structure interfaces under monotonic and cyclic loadings. The features of the interface including the strain-softening behavior, phase transformation, steady-state, and dilatancy behavior were described by the proposed model with satisfactory accuracy. The proposed model does not require additional concepts such as damage or disturbance, and the model parameters can be obtained easily using straight-forward analyses of the results obtained from constant normal stress tests. Moreover, the results of the proposed model showed its capability in predicting the experimental results obtained from various...