Search for: reinforced-concrete
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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) Asgarpoor, M ; Gharavi, A ; Epackachi, S ; Sharif University of Technology
    Elsevier Ltd  2021
    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... 

    A simplified MCFT for shear capacity scaling of R/C beams

    , Article 16th European Conference of Fracture, 3 July 2006 through 7 July 2006 ; 2006 , Pages 1363-1364 ; 9781402049712 (ISBN) Kazemi, M. T ; Broujerdian, V ; Sharif University of Technology
    Kluwer Academic Publishers  2006
    It is well known that shear strength of beams without stirrups shows a strong size effect. At present, several formulas of size effect are used by some codes and suggested by various researchers. Most of those formulas are not in agree with fracture mechanics. Recently, a simple formula based on modified compression field theory, MCFT, was proposed (Collins and Kuchma [1], Lubell et al. [2]), which shows a size effect stronger than the size effect formula based on fracture mechanics, proposed by Bazant (e.g. Bazant and Kazemi [3], Bazant and Yu [4]). In this paper it is shown that with some refined considerations, formulas are resulted in agree with Fracture Mechanics concept. In the derived... 

    Flexural Behavior of Concrete Beams Strengthened by Classical Method and Comparing The Results with Strengthening by FRP

    , M.Sc. Thesis Sharif University of Technology Moradkhani Pour, Behnam (Author) ; Khaloo, Alireza (Supervisor)
    Retrofitting and strengthening existing structures is one of the most important concepts of structural and earthquake engineering. Strengthening of structures could be due to changes in application and applied load, errors in calculation, mistakes in construction, weakness of old codes, structural height increases and changes in environmental conditions. Different methods for increasing the flexural strength and ductility of reinforced concrete beams, as one of the major structural components, have been presented. This research presents an experimental study on the strengthening of reinforced concrete beams by reinforced concrete jackets (classical method) and Fiber Reinforced Polymer (FRP)... 

    Investigation of the Effect of Chlorine ion Concentration on Corrosion of Steel Reinforcement in Concrete

    , M.Sc. Thesis Sharif University of Technology Hajian, Morteza (Author) ; Afshar, Abdollah (Supervisor)
    Today, in our beloved country of Iran and other parts of the world, reinforced concrete structures are used in large industrial projects, in some cases we see their very early failure even before the time of operation. This issue in the southern coasts of the country due to special weather conditions (humidity and high temperature) and the existence of the offensive ions such as chlorine and sulfate in seawater are more important and we always face with severe corrosion of reinforcement and reduced service life of concrete structures in these areas. Despite this, little research has been done on the reliability of concrete facilities in the vicinity of the Caspian Sea in the north of the... 

    Comparing calculation methods of storey stiffness to control provision of soft storey in seismic codes

    , Article Earthquake and Structures ; Volume 11, Issue 1 , 2016 , Pages 1-23 ; 20927614 (ISSN) Tabeshpour, M. R ; Noorifard, A ; Sharif University of Technology
    Techno Press  2016
    Numerous buildings have been damaged or destroyed in previous earthquakes by developing soft storey. Almost all the seismic codes have provisions to prevent soft storey in structures, most of them have recommended the ratio of stiffness between adjacent storeys, but none of them has proposed the method to calculate the storey stiffness. On the other hand a great number of previous researches on stiffness have been focused on approximate methods and accurate methods by using analytical softwares have been almost neglected. In this study, six accurate methods for calculating the storey stiffness have been studied on 246 two-bay reinforced concrete frames. It is shown with the results of the... 

    A precise solution for prediction of fiber-reinforced concrete behavior under flexure

    , Article Journal of Zhejiang University: Science A ; Volume 12, Issue 7 , 2011 , Pages 495-502 ; 1673565X (ISSN) Ahmadi, R ; Ghoddousi, P ; Sharifi, M ; Bahreh, V. M ; Sharif University of Technology
    This paper presents a precise solution to predict the behavior of steel fiber reinforced concrete (SFRC) under the four point bending test (FPBT). All the force components at the beam section (before and after cracking) are formulated by applying these assumptions: a realistic stress-strain model is used for concrete behavior in compression, a linear response is considered for the uncracked tension region in a concrete constitutive model, and an exponential relationship is proposed as a stress-crack opening in the crack region which requires two parameters. Then the moment capacity of the critical cracked section is calculated by using these forces and satisfying equilibrium law at the... 

    Study of behavior of reinforced concrete beams with smart rebars using finite element modeling

    , Article International Journal of Civil Engineering ; Volume 8, Issue 3 , September , 2010 , Pages 221-231 ; 17350522 (ISSN) Khaloo, A. R ; Eshghi, I ; Piran Aghl, P ; Sharif University of Technology
    In this paper the response of cantilevered reinforced concrete (RC) beams with smart rebars under static lateral loading has been numerically studied, using Finite Element Method. The material used in this study is SuperelasticShape Memory Alloys (SE SMAs) which contains nickel and titanium elements. The SE SMA is a unique alloy that has the ability to undergo large deformations and return to their undeformed shape by removal of stresses. In this study, different quantities of steel and smart rebars have been used for reinforcement andthe behavior of these models under lateral loading, including their load-displacement curves, residual displacements, and stiffness, were discussed. During... 

    Nonlinear finite element modeling of shear-critical reinforced concrete beams using a set of interactive constitutive laws

    , Article International Journal of Civil Engineering ; Volume 14, Issue 8 , 2016 , Pages 507-519 ; 17350522 (ISSN) Broujerdian, V ; Kazemi, M. T ; Sharif University of Technology
    Iran University of Science and Technology  2016
    Complex nature of diagonal tension accompanied by the formation of new cracks as well as closing and propagating preexisting cracks has deterred researchers to achieve an analytical and mathematical procedure for accurate predicting shear behavior of reinforced concrete, and there is the lack of a unique theory accepted universally. Shear behavior of reinforced concrete is studied in this paper based on recently developed constitutive laws for normal strength concrete and mild steel bars using the nonlinear finite element method. The salient feature of these stress-strain relations is to account the interactive effects of concrete and embedded bars on each other in a smeared rotating crack... 

    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) Soleimanian, E ; Toufigh, V ; Sharif University of Technology
    Springer  2019
    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... 

    Predictive equations for drift ratio and damage assessment of RC shear walls using surface crack patterns

    , Article Engineering Structures ; Volume 190 , 2019 , Pages 410-421 ; 01410296 (ISSN) Momeni, H ; Dolatshahi, K. M ; Sharif University of Technology
    Elsevier Ltd  2019
    The purpose of this paper is to quantify the extent of damage of rectangular reinforced concrete shear walls after an earthquake using surface crack patterns. One of the most important tasks after an earthquake is to assess the safety and classify the performance level of buildings. This assessment is usually performed by visual inspection that is prone to significant errors. In this research, an extensive database on the images of damaged rectangular reinforced concrete shear walls is collected from the literature. This database includes more than 200 images from experimental quasi-static cyclic tests. Using the concept of fractal geometry, several probabilistic models are developed by... 

    Seismic Performance of Composite RCS Moment Frames

    , M.Sc. Thesis Sharif University of Technology Tavasoli Yousef Abadi, Elmira (Author) ; Kazemi, Mohammad Taghi (Supervisor)
    Composite Reinforced Concrete-Steel (RCS) frames which have reinforced concrete columns and steel beams attracted a lot of attention in recent years. They take advantage from the benefits of both reinforced concrete and steel frames thorough using the optimum combination of concrete and steel structural elements. In this research six structures including three 3-story, and three 6-story buildings are designed in a region with very high seismicity risk. These structures include composite RCS moment frames, special steel moment frames, and reinforced concrete special moment frames. RCS moment frames which are designed they not only have reinforced concrete columns similar to reinforced... 

    Experimental Investigation on Effects of Hybrid Fibers on Rheological, Mechanical, and Durability Properties of High-Strength SCC

    , M.Sc. Thesis Sharif University of Technology Tabatabaeian, Mojtaba (Author) ; Khaloo, Alireza (Supervisor)
    The aim of the present study is to investigate the effects of using hybrid fibers on rheological, mechanical and durability properties of the high-strength Self-Consolidating Concrete (SCC). For this purpose, two types of fibers including hooked-end steel fibers and polypropylene fibers were used. In this study, a total of eleven mixtures were used: one as a control mix, one containing 0.5% steel fibers, four containing 0.5% hybrid fibers (steel and polypropylene), one containing 1.0% steel fibers and the four containing 1.0% hybrid fibers (steel and polypropylene). For investigating the rheological properties, slump flow, J-ring and V-funnel tests were performed. Mechanical properties were... 

    Strengthening RC Arch Structures Using FRP Laminate

    , M.Sc. Thesis Sharif University of Technology Dehshahri, Fataneh (Author) ; Khaloo, Alireza (Supervisor) ; Kazemi, Mohammad Taghi (Supervisor)
    Although considerable researches have been conducted on strengthening RC structures using FRP method during past years, a few researches have been reported on RC arch or curved structures strengthened by FRP. In this study, behavior of RC arches strengthened by FRP strips is investigated. The behavior of strengthened RC arches under gravitational load is analyzed using finite elements method. The arches are modeled by appropriate software in order to evaluate the behavior. The structural behavior of arches is more complicated. So, the estimation of the effect of strengthening using FRP technique on such structures is hard in comparison with traditional RC beams. In this study, the effect of... 

    Performance Evaluation of Reinforced Concrete Bridge Deck Strengthened with FRP Laminates

    , M.Sc. Thesis Sharif University of Technology Bozorgi, Neda (Author) ; Khaloo, Alireza (Supervisor)
    According to key importance of bridges in transportation system vital routes, a need to study and survey of bridges against destructive factors exist. Among these, bridges with concrete deck are widely used. One of the most important factors in destruction of these bridges is steel reinforcements corrosion and destruction of bridge deck. So in order to reduce the aggregation of reinforcements in critical sections and performance improvement of deck beams, a reinforcing substance which is not only resistant against corrosion but benefits from high resistance and stiffness is implemented.In this research the case studied bridge is simulated by finite elements software in two cases; reinforced... 

    The seismic performance of new detailing for RCS connections

    , Article Journal of Constructional Steel Research ; Volume 91 , 2013 , Pages 76-88 ; 0143974X (ISSN) Alizadeh, S ; Attari, N. K. A ; Kazemi, M. T ; Sharif University of Technology
    Over the past few decades considerable experimental and numerical studies have been conducted on the Reinforced Concrete columns to Steel beams (RCS) connections. Most of those researches have focused on studying the joint failure modes and ultimate joint strength of specimens utilizing strong beams and columns with weak joints. In this paper, two interior RCS connections were designed based on the Strong Column-Weak Beam (SCWB) criterion. Both specimens were tested under quasi-static reversed cyclic loading. The tested specimens were modeled by a finite element method, which verified with experimental results. Several models with different joint details were investigated using the verified... 

    Comparison of nonlinear behavior of steel moment frames accompanied with RC shear walls or steel bracings

    , Article Structural Design of Tall and Special Buildings ; Volume 22, Issue 14 , 2013 , Pages 1062-1074 ; 15417794 (ISSN) Esmaeili, H ; Kheyroddin, A ; Kafi, M. A ; Nikbakht, H ; Sharif University of Technology
    In this paper, the seismic behavior of dual structural systems in forms of steel moment-resisting frames accompanied with reinforced concrete shear walls and steel moment-resisting frames accompanied with concentrically braced frames, have been studied. The nonlinear behavior of the mentioned structural systems has been evaluated as, in earthquakes, structures usually enter into an inelastic behavior stage and, hence, the applied energy to the structures will be dissipated. As a result, some parameters such as ductility factor of structure (μ), over-strength factor (Rs) and response modification factor (R) for the mentioned structures have been under assessment. To achieve these objectives,... 

    An investigation on the effect of cement and silica fume on properties of self-compacting concrete

    , Article Proceedings of the 13th East Asia-Pacific Conference on Structural Engineering and Construction, EASEC 2013 ; September , 2013 Moshiri, F ; Atashnama, A ; Panahi, M ; Gharebaghi, R ; Mahlouji, J ; Sharif University of Technology
    Hokkaido University collection of Scholarly Academic Papers, HUSCAP  2013
    Self-Compacting concrete (SCC) is identified as a high performance concrete with the ability of self compaction, using its own weight without any external vibration. SCC is able to fill congested area and voids, even in highly reinforced concrete members whilst it flows without segregation. The fresh properties of SCC such as workability can be determined using different tests including slump-flow, J ring, V-funnel, U box, L box, GTM and column technique. In this paper the effect of different amount of cementitious material, silica fume and W/C ratios on workability and compressive strength of SCC are investigated. The results indicate that the workability of mixtures is reduced by... 

    The corrosion investigation of rebar embedded in the fibers reinforced concrete

    , Article Construction and Building Materials ; Volume 35 , October , 2012 , Pages 564-570 ; 09500618 (ISSN) Kakooei, S ; Akil, H. M ; Dolati, A ; Rouhi, J ; Sharif University of Technology
    Elsevier  2012
    One effective method for preventing corrosion of steel reinforcement and improving the mechanical properties of concrete is changing the physical nature of concrete by adding different materials. In this study, we have used polypropylene fibers as an additional material. We have compared the corrosion rate of rebar using different volume ratios and sizes of polypropylene fibers. Reinforcement potential increased as the amount of fibers increased from 0 to 2 kg m -3. The polypropylene fibers delay the initial corrosion process by preventing cracking, thereby decreasing permeability of the concrete. In addition, the corrosion rate of concrete samples made with Kish Island coral aggregate was... 

    Experimental investigation of RCS connections performance using self-consolidated concrete

    , Article Journal of Constructional Steel Research ; Volume 114 , November , 2015 , Pages 204-216 ; 0143974X (ISSN) Alizadeh, S ; Attari, N. K. A ; Kazemi, M. T ; Sharif University of Technology
    Elsevier Ltd  2015
    The cyclic behavior of RCS connection consisted of Reinforced Concrete (RC) columns and Steel (S) beams is studied in this paper. Two interior connections are investigated experimentally. The joint of the first specimen is designed according to ASCE 1994 guideline, while the second specimen has a new proposed joint detail. Self-consolidating concrete is used in both specimens. Self-consolidating concrete could improve constructability of the congested joint of RCS frames. The specimens detail include steel band plates, face bearing plates, L-shaped joint stirrups, and steel doubler plate for the panel zone. The proposed joint detail consists of additional bearing plates, which cause an... 

    A model for the evolution of concrete deterioration due to reinforcement corrosion

    , Article Mathematical and Computer Modelling ; Volume 52, Issue 9-10 , November , 2010 , Pages 1403-1422 ; 08957177 (ISSN) Shodja, H. M ; Kiani, K ; Hashemian, A ; Sharif University of Technology
    One of the most crucial factors affecting the service life of reinforced concrete (RC) structures attacked by aggressive ions is reinforcement corrosion. As the steel corrosion progresses, crack propagation in concrete medium endangers the serviceability and the strength of RC structural members. In this study, a nonlinear mathematical model for determining the displacement and stress fields in RC structures subjected to reinforcement corrosion is introduced. For corrosion products, a nonlinear stress-strain relation which has been previously confirmed by experimental data is incorporated in the present analysis. In formulation of the governing equations for steel-rust-concrete composite,...