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reinforced-concrete
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Finite Element Analysis of RC Deep Beams Strengthened Using FRP
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Alireza (Supervisor)
Abstract
In the last decade Fiber Reinforced Polymer (FRP) widely has been used to strengthening the reinforced concrete (RC) members. Most of the research works have been concentrated on the design of shear members with FRP layers. Based on the reported results, increasing the shear reinforcement more than a certain amount, the shear capacity and ultimate strength of reinforced concrete deep beam does not increased, On the other hand, The presence of web openings in such beams is frequently required to provide accessibility such as doors and windows or to accommodate essential services such as ventilating and air conditioning ducts, So the external strengthening of the reinforced concrete deep beams...
Use of polymer fibres recovered from waste car timing belts in high performance concrete
, Article Construction and Building Materials ; Volume 80 , April , 2015 , Pages 31-37 ; 09500618 (ISSN) ; Esrafili, A ; Kalani, M ; Mobini, M. H ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
The present paper discusses the possibility of adding recycled polymer fibres to high performance concrete (HPC). Fibres used in this study were recovered from discarded car timing belts. To investigate different characteristics of the concrete specimens several destructive and non-destructive tests, such as compressive strength, modulus of rupture, flexural toughness, ultrasonic velocity and electrical resistance tests were carried out. In addition, slump flow tests were conducted on the fresh concrete. Experimental results from the study showed that the use of low percentages (up to 0.5%) of waste fibres improved the modulus of rupture and flexural toughness. Based on ultrasonic and...
Uncertainty quantification in seismic collapse assessment of the Iranian code-conforming RC buildings
, Article Scientia Iranica ; Volume 27, Issue 4 , 2021 , Pages 1786-1802 ; 10263098 (ISSN) ; Ghaemian, M ; Hariri Ardebili, M. A ; Sharif University of Technology
Sharif University of Technology
2021
Abstract
Abstract. Structural collapse is the main concern for the existing structures which are built in the seismic-prone regions. Therefore, the primary goal of the seismic provisions in building codes is to prevent the global collapse. Iran is located in the Alpine-Himalayan belt, and has experienced some of the most destructive earthquakes in the past century. To evaluate the extent to which the Iranian building code provisions meet the abovementioned objective, the authors conducted a detailed assessment of collapse risk on a set of moderate moment resisting Reinforced Concrete (RC) buildings. While many features might affect the seismic performance of the RC structures, this study considers...
The tensile performance of FRP bars embedded in concrete under elevated temperatures
, Article Construction and Building Materials ; Volume 211 , 2019 , Pages 1138-1152 ; 09500618 (ISSN) ; Vatani Oskouei, A ; Khaneghahi, M. H ; Shoaei, P ; Ozbakkaloglu, T ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
In this research, the mechanical properties of glass and carbon fiber reinforced polymer (FRP) bars with epoxy resin matrices embedded in concrete were investigated under an extensive range of elevated temperatures (i.e., 25–800 °C). Embedded FRP bars with various bar diameters were studied in order to determine bar diameter influence on the results. In addition, analysis of variance (ANOVA) was performed on the experimental results to investigate the contribution of exposure temperature and bar diameter to the tensile behavior of embedded in concrete FRP bars at elevated temperatures. The results show that the tensile strength of embedded FRP bars generally decreases with increasing...
The structural performance of monolithic intersecting walls in a tall reinforced concrete building
, Article Structural Design of Tall and Special Buildings ; Volume 17, Issue 1 , 2008 , Pages 1-23 ; 15417794 (ISSN) ; Samadi, M ; Sharif University of Technology
2008
Abstract
Results of the seismic performance assessment of a new structural system that has been used in a 54-story reinforced concrete building are presented. The structure, which is still under construction, and has a 'Y-shape' form, utilizes a special structural system that does not include any beams or columns. Instead, walls and slabs are used for carrying both gravitational and lateral loads. The general distinctions of the system are discussed. The structural efficiency of the system is compared with other conventional systems in some existing tall buildings. The seismic responses and dynamic behavior of the structure that were achieved by conducting various analyses are presented. The effects...
The seismic performance of new detailing for RCS connections
, Article Journal of Constructional Steel Research ; Volume 91 , 2013 , Pages 76-88 ; 0143974X (ISSN) ; Attari, N. K. A ; Kazemi, M. T ; Sharif University of Technology
2013
Abstract
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...
The effects of elevated temperatures on the performance of concrete-filled pultruded GFRP tubular columns
, Article Thin-Walled Structures ; Volume 169 , 2021 ; 02638231 (ISSN) ; Khaloo, A ; Azizmohammadi, M ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Usage of concrete-filled pultruded glass fiber-reinforced polymer (GFRP) tubes (CFPGT) as columns can increase the service life of structures. However, marine structures such as oil platforms are always prone to fire because of the low resistance to the elevated temperatures. The purpose of this investigation is to evaluate the effects of concrete core strength (30 and 60 MPa), and exposure temperature (25, 100, 200, 300, and 400 °C) and time (60 and 120 min) on the compressive and bond behavior of CFPGTs. The properties of unexposed and exposed concrete core, pultruded GFRP hollow tubes, and CFPGTs were determined via compressive and disk-split tests. Also, the push-out test was used to...
The effect of transverse steel and FRP jacket confinement on mechanical properties of concrete cylinders: An experimental study
, Article ISEC 2011 - 6th International Structural Engineering and Construction Conference: Modern Methods and Advances in Structural Engineering and Construction ; 2011 , Pages 827-832 ; 9789810879204 (ISBN) ; Javid, Y ; Khosravi, H ; Yazdani S ; Cheung S. O ; Singh A ; Ghafoori N ; American Society of Civil Engineers (ASCE); Architectural Institute of Japan (AIJ); Chartered Institute of Building (CIOB); et al.; University of Nevada Las Vegas (UNLV), College of Engineering; Wayne State College of Engineering ; Sharif University of Technology
Abstract
This paper presents the results of an experimental study on the behavior of concrete cylinders externally wrapped with fiber-reinforced polymer (FRP) composites and internally reinforced with steel spirals. The experimental work was performed by testing 30 concrete cylinders (120 × 400mm2) subjected to pure compression to achieve the complete stress-strain curve. Test specimens were confined with various internal and external confinement ratios and different types of confining material such as steel, Carbon FRP (CFRP) and Glass FRP (GFRP). The compressive strength, corresponding strain and the complete stress-strain curve of the tested specimenswere indicated. The test results showthat the...
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) ; Akil, H. M ; Dolati, A ; Rouhi, J ; Sharif University of Technology
Elsevier
2012
Abstract
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...
Study the effect of architectural modification on fracture behavior of Al-DRA composite
, Article Mechanics of Advanced Materials and Structures ; Vol. 21, issue. 8 , 2014 , Pages 662-668 ; ISSN: 15376494 ; Khalili, S ; Bagheri, R ; Simchi, A ; Sharif University of Technology
Abstract
An architectural modification method was utilized to improve fracture toughness of discontinuously reinforced aluminum (DRA) composites. Al-DRA composites having a structure similar to that of reinforced concrete were fabricated. The number of reinforcing DRA rods within Al matrix and volume fraction of SiC particles in DRA were altered to evaluate their effect on fracture behavior of these materials. It was found that architectural modification does not have any destructive influence on elastic modulus and yield strength of the composite. Moreover, the success of this method on toughness improvement strongly depends on the occurrence of debonding between Al and DRA regions upon loading
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) ; Eshghi, I ; Piran Aghl, P ; Sharif University of Technology
2010
Abstract
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...
Studying higher mode effects on the performance of nonlinear static analysis methods considering near-fault effects
, Article KSCE Journal of Civil Engineering ; Volume 17, Issue 2 , March , 2013 , Pages 426-437 ; 12267988 (ISSN) ; Moradnejad, H. R ; Rouhanimanesh, M. S ; Sarvghad Moghadam, A ; Sharif University of Technology
2013
Abstract
Daily development in civil engineering arena and the importance of economical aspects in the design of structures have motivated the engineers to shift their approaches from designing upon strength to designing upon performance. This is of more importance regarding the forces induced by earthquakes which have unpredicted and random nature. However, it is not possible to design or assess exactly the structural performance against strong ground motion using analytical methods which are applied for static loads and therefore precise dynamic analysis methods are needed. Despite significant progress in the analytical methods and engineering software, using nonlinear time history analysis is very...
Strengthening design limitations of an RC frames using FRP column wrapping considering column-to-beam strength ratio
, Article Scientia Iranica ; Volume 14, Issue 5 , 2007 , Pages 405-413 ; 10263098 (ISSN) ; Esmaili, A ; Sharif University of Technology
Sharif University of Technology
2007
Abstract
The aim of this paper is to study the influence of the column-to-beam strength ratio on the seismic strengthening of a column with a Fiber-Reinforced Plastic (FRP) wrapping system. FRP wrapped Reinforced Concrete (RC) columns are analyzed to obtain moment-curvature curves using FRP confined concrete characteristics. A pushover analysis of a 2D model was performed on one and three-story moment-resisting frames, with different column-to-beam strength ratios. The results indicate that FRP strengthening is more efficient in frames with a low ratio of column-to-beam strength, due to the type of lateral failure mechanism of the frame. Also, high values of the column-to-beam strength ratio can be...
Strength and stiffness estimation of damaged reinforced concrete shear walls using crack patterns
, Article Structural Control and Health Monitoring ; Volume 27, Issue 4 , February , 2020 ; Dolatshahi, K. M ; Sharif University of Technology
John Wiley and Sons Ltd
2020
Abstract
The purpose of this paper is to estimate the stiffness and strength of damaged rectangular reinforced concrete shear walls after an earthquake using surface crack patterns. Assessing the damage severity of buildings after an earthquake is an important part of the emergency inspection operation of buildings. Expert inspectors tag buildings into two categories of safe or unsafe that are usually affected by subjective decisions, which may result in catastrophic events reported in previous earthquakes. In this research, an extensive database on the images of damaged rectangular reinforced concrete shear walls (RCSWs) is collected and used to develop predictive equations for updated stiffness and...
Spatial analysis of damage evolution in cyclic-loaded reinforced concrete shear walls
, Article Journal of Building Engineering ; Volume 49 , 2022 ; 23527102 (ISSN) ; Dolatshahi, K. M ; Ebrahimkhanlou, A ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
This paper introduces a probabilistic framework to quantify the spatial distribution of cracking and crushing in rectangular reinforced concrete shear walls at different drift ratios. In this research, a comprehensive probabilistic spatial analysis is conducted on an extensive collected database of reinforced concrete shear walls tested under the quasi-static cyclic loading. The database includes 235 images of 72 damaged walls with various geometry and material properties at different drift ratios between 0.0 and 4.0%. Various image processing filters are implemented to the images to highlight the wall areas that are more prone to cracking and crushing. Then, advanced statistical analysis is...
Soil-Structure interaction effect on fragility curve of 3D models of concrete moment-resisting buildings
, Article Shock and Vibration ; Volume 2018 , 2018 ; 10709622 (ISSN) ; Rahimzadeh Rofooei, F ; Nekooei, M ; Sharif University of Technology
Hindawi Limited
2018
Abstract
This paper presents the probabilistic generation of collapse fragility curves for evaluating the performance of 3D, reinforced concrete (RC) moment-resisting building models, considering soil-structure interaction (SSI) by concentration on seismic uncertainties. It considers collapse as the loss of lateral load-resisting capacity of the building structures due to severe ground shaking and consequent large interstory drifts intensified by P-Δ effects as well as the strength and stiffness deterioration of their lateral load carrying systems. The estimation of the collapse performance of structures requires the relation between the intensity measure (IM) and the probability of collapse...
Smeared rotating crack model for reinforced concrete membrane elements
, Article ACI Structural Journal ; Volume 107, Issue 4 , 2010 , Pages 411-418 ; 08893241 (ISSN) ; Kazemi, M. T ; Sharif University of Technology
2010
Abstract
A set of stress-strain relations for normal-strength concrete and mild steel bars embedded in concrete is presented in this paper. The salient features of the proposed constitutive laws are: 1) considering the effect of reinforcement ratio on average stressstrain relationships of cracked concrete; and 2) considering the gradual reduction of average stiffness of steel bars embedded in concrete. Equilibrium, compatibility, and constitutive relationships were incorporated into an algorithm to obtain a procedure for analyzing reinforced concrete membrane elements. Corroboration with data from panel test specimens shows that the presented model provides good predictions for the entire...
Seismic shear strengthening of R/C columns with ferrocement jacket
, Article Cement and Concrete Composites ; Volume 27, Issue 7-8 , 2005 , Pages 834-842 ; 09589465 (ISSN) ; Morshed, R ; Sharif University of Technology
2005
Abstract
This paper presents results of an experimental study to evaluate a retrofit technique for strengthening shear deficient short concrete columns. In this technique a ferrocement jacket reinforced with expanded steel meshes is used for retrofitting. Six short concrete columns, including four strengthened specimens, were tested. Specimens were under a constant compressive axial force of 15% of column axial load capacity based on original concrete gross, A g, and the concrete compressive strength, fc′. Main variables were the spacing of ties in original specimens and the volume fraction of expanded metal in jackets. Original specimens failed before reaching their nominal calculated flexural...
Seismic retrofit of large-scale reinforced concrete columns by prestressed high-strength metal strips
, Article Proceedings of the 2009 Structures Congress - Don't Mess with Structural Engineers: Expanding Our Role, 30 April 2009 through 2 May 2009, Austin, TX ; 2009 , Pages 2863-2872 ; 9780784410318 (ISBN) ; Samadi, M ; Sharif University of Technology
2009
Abstract
This paper presents the results of an experimental study on the application of pre-stressed high strength metal strips in retrofit of RC columns. Six 2/3 scale were deliberately designated with insufficient transverse reinforcement details and tested under constant axial and cyclic lateral load reversals. The level of axial load and the pattern of strengthening were parameters of this study. It was observed that the technique has been capable to enhance the lateral behavior of columns significantly, in terms of ductility. Very ductile behavior was obtained. The height-wise variations of lateral strain on confining strips are studied. The analysis of the fiber-based model of tested columns...
Seismic response of SiO2 nanoparticles-reinforced concrete pipes based on DQ and newmark methods
, Article Computers and Concrete ; Volume 19, Issue 6 , 2017 , Pages 745-753 ; 15988198 (ISSN) ; Kolahchi, R ; Sharif University of Technology
Techno Press
2017
Abstract
Dynamic analysis of a concrete pipes armed with Silica (SiO2) nanoparticles subjected to earthquake load is presented. The structure is modeled with first order shear deformation theory (FSDT) of cylindrical shells. Mori-Tanaka approach is applied for obtaining the equivalent material properties of the structure considering agglomeration effects. Based on energy method and Hamilton's principle, the motion equations are derived. Utilizing the harmonic differential quadrature method (HDQM) and Newmark method, the dynamic displacement of the structure is calculated for the Kobe earthquake. The effects of different parameters such as geometrical parameters of pipe, boundary conditions, SiO2...