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reinforced-concrete
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Fibrous and non-fibrous Perlite concretes–experimental and SEM studies
, Article European Journal of Environmental and Civil Engineering ; Volume 22, Issue 2 , 2018 , Pages 138-164 ; 19648189 (ISSN) ; Eslami, E ; Anvari, A ; Sharif University of Technology
Taylor and Francis Ltd
2018
Abstract
Mechanical properties and microstructural analysis of Expanded Perlite Aggregate (EPA) concretes are presented. Using 10% EPA, the effects of using various types of fibre were investigated. For all specimens, fibrous and non-fibrous, the compressive and the splitting tensile strengths were obtained. Complete stress–strain curves for fibre-reinforced specimens were obtained. A new index for representing the toughness of fibre-reinforced Perlite concretes is introduced. The addition of fibres substantially increased the splitting tensile strength. Steel fibres with “indentations” had the best performance in this regard. Regarding the toughness, specimens with “hooked” steel fibres performed...
Computational predictions for estimating the maximum deflection of reinforced concrete panels subjected to the blast load
, Article International Journal of Impact Engineering ; Volume 139 , 2020 ; Khalili, M. R ; Karami, B ; Rabczuk, T ; Shishegaran, A ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
We investigate the resistance of reinforced concrete panels (RCPs) due to explosive loading using nonlinear finite element analysis and surrogate models. Therefore, gene expression programming model (GEP), multiple linear regression (MLR), multiple Ln equation regression (MLnER), and their combination are used to predict the maximum deflection of RCPs. The maximum positive and negative errors, mean of absolute percentage error (MAPE), and statistical parameters such as the coefficient of determination, root mean square error (RMSE). Normalized square error (NMSE), and fractional bias are utilized to evaluate and compare the performance of the models. We also present a novel statistical table...
Dynamic performance enhancement of RC slabs by steel fibers vs. externally bonded GFRP sheets under impact loading
, Article Engineering Structures ; Volume 213 , 2020 ; Khaloo, A ; Sadraie, H ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Recently, to improve the dynamic behavior of Reinforced Concrete (RC) slabs under impact load, the methods of externally bonding Glass Fiber Reinforced Polymer (GFRP) sheets to slab and internally reinforcing concrete by steel fibers have been proposed. Nevertheless, it is required to investigate the comparison between these two methods on response of RC slabs under impact loads. In this study, the influence of volume fraction of steel fibers, the number of GFRP sheet layers (one or two) and the arrangement of GFRP sheets (covering the whole or parts of surface), are examined. Performance of fourteen 1000 × 1000 × 75 mm concrete slabs including one plain slab, one steel RC slab, three steel...
Experimental comparison of cyclic behavior of RC columns strengthened with TRC and FRP
, Article Bulletin of Earthquake Engineering ; Volume 19, Issue 7 , 2021 , Pages 2941-2970 ; 1570761X (ISSN) ; Zargaran, M ; Rahimzadeh Rofooei, F ; Attari, N. K. A ; Sharif University of Technology
Springer Science and Business Media B.V
2021
Abstract
Seven half-scale reinforced concrete (RC) columns with supporting beam were experimentally studied under combined axial and lateral cyclic loading. The specimens were categorized in two groups based on reinforcement ratios. Three specimens were strengthened with carbon fiber reinforced polymer (CFRP) and glass fiber reinforced polymer (GFRP) sheets. Other specimens were strengthened using a high strength mortar reinforced with textile mesh (textile reinforced concrete (TRC)). Strengthening of specimens were carried out using a vertical layer and a horizontal layer of FRP sheet or two vertical and two horizontal layers of textile meshes for TRC specimens. Since the weight of each layer of...
Data-driven damage assessment of reinforced concrete shear walls using visual features of damage
, Article Journal of Building Engineering ; Volume 53 , 2022 ; 23527102 (ISSN) ; Dolatshahi, K. M ; Asjodi, A. H ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
This paper proposes a damage assessment framework based on the visual features of a damaged reinforced concrete shear wall, such as crack pattern distribution, crushing areal density, aspect ratio, and the presence of the boundary condition. The study contains two parts including: identifying the performance level of the damaged walls (i.e., Immediate Occupancy, Life Safety, and Collapse Prevention) and estimating the residual strength and drift ratio of the walls. The research database contains 236 images of 72 reinforced concrete shear walls tested in the laboratory under the quasi-static cyclic loadings at various drift ratios between 0 and 4%. To identify the performance level of a...
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...
Determining shear capacity of ultra-high performance concrete beams by experiments and comparison with codes
, Article Scientia Iranica ; Volume 26, Issue 1A , 2019 , Pages 273-282 ; 10263098 (ISSN) ; Joghataie, A ; Sharif University of Technology
Sharif University of Technology
2019
Abstract
In this research, 19 specimens of ultra-high performance fiber-reinforced concrete rectangular beams were made and their shear resistance was determined experimentally. The results were compared with estimations by ACI 318, RILEM TC 162-TDF, Australian guideline, and Iranian national building regulations. To compare the code estimations, the ratio of experimental shear strength to predicted shear strength was calculated for each code. This ratio is in fact a measure of safety factor on the one hand and a measure of precision of the estimation on the other hand. Based on the results of both studies, the authors concluded that the Australian guideline, with the amount of 2.5, provided the...
Determining shear capacity of ultra-high performance concrete beams by experiments and comparison with codes
, Article Scientia Iranica ; Volume 26, Issue 1A , 2019 , Pages 273-282 ; 10263098 (ISSN) ; Joghataie, A ; Sharif University of Technology
Sharif University of Technology
2019
Abstract
In this research, 19 specimens of ultra-high performance fiber-reinforced concrete rectangular beams were made and their shear resistance was determined experimentally. The results were compared with estimations by ACI 318, RILEM TC 162-TDF, Australian guideline, and Iranian national building regulations. To compare the code estimations, the ratio of experimental shear strength to predicted shear strength was calculated for each code. This ratio is in fact a measure of safety factor on the one hand and a measure of precision of the estimation on the other hand. Based on the results of both studies, the authors concluded that the Australian guideline, with the amount of 2.5, provided the...
Seismic Rehabilitation of Reinforced Concrete Structures Using Eccentric Steel Bracing
, M.Sc. Thesis Sharif University of Technology ; Kazemi, Mohammad Taghi (Supervisor)
Abstract
The seismic performance of a low-rise nonductile reinforced concrete (RC) building rehabilitated using eccentric steel bracing is investigated. At first three-story building was Modeled using sap 2000 computer program then analyzed and getting the results. The effectiveness of the eccentric steel bracing in rehabilitating the building was examined. The effect of distributing the steel bracing over the height of the RC frame on the seismic performance of the rehabilitated building was studied. The behavior of the nonductile RC frame members is represented by a beam–column element capable of modeling the strength deterioration and the effect of the axial force on the yield moment and the...
On the Dynamic Response of Funicular Shells and Evaluation of the Behavior Factor
, M.Sc. Thesis Sharif University of Technology ; Mofid, Masoud (Supervisor)
Abstract
Dynamic behavior of space structures are of great complexities. On the event of severe earthquake these structures exhibit high resistance and on the other hand, their high rigidity and small deformation makes it necessary to pay attention to their dynamic behavior, especially when combined with other types of structural systems. Also due to lack of sufficient codes and references, their dynamic behavior is still unknown to a great extend. Among these kinds of structures, reinforced concrete double curvature shells, and especially funicular shells, are much more important than others. In this thesis, dynamic response of these kind of structures, especially reinforced concrete domes, in...
Improvement in Reinforced Concrete Beam-Column Connections Behavior using Steel Plates
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Ali Reza (Supervisor)
Abstract
Performance of reinforced concrete frames is highly dependent on detailing of the joint connections between its members, such as beams and columns. To have a good structural behavior, joints must show ductile behavior and designed based on the philosophy of strong column-weak beam. In the case of sever lacking ductility, strength or even rigidity of the connections, or having a weak column-strong beam, in the existing structures, there is a need for seismic upgrading of the connection. There are several ways for seismic upgrading of this type of connections.In this research, using steel plates for seismic upgrading of Concrete Beam-Column connections subjected to axial and cyclic loads has...
Finite Element Modelling of Damage in FRC using Microplane Method
, M.Sc. Thesis Sharif University of Technology ; Kazemi, Mohammad Taghi (Supervisor)
Abstract
In concrete which is a quasi-brittle material failure initially occurs between aggregate and mortars. Fibers of all orientations, randomly embedded in FRC, serve to restrict and delay the coalescence of micro-cracks, micro-voids and micro-slips into wide continuous cracks. While the fibers increase the uniaxial tensile and compressive strength only moderately, they are very effective for enhancing the ductility and energy absorption capability. This elevates structure resistance to impact, ground-shock and blast. One of the most successful efforts toward reaching a macroscopic model which can take micromechanical properties into account is the Microplane model. In this microscopic...
Seismic Behavior of Steel Beam to Reinforced Concrete Column Connections
, M.Sc. Thesis Sharif University of Technology ; Kazemi, Mohammad Taghi (Supervisor)
Abstract
In recent years, composite systems comprised of reinforced concrete columns and steel beams, have taken consideration. This system took its own advantages both from steel and concrete systems. Joints of this system categorized into through-beam-type and through-column-type. In this research, after reviewing past studies, two kinds of the joints were modeled in ABAQUS finite element program and seismic performance of these two joints were evaluated. These two selected joints were tested by Chin-Tun Chen and Cheng-Chih Chen ( ) and also Hiroshi Kuramoto and Isao Nishiyama ( ). After verifying the finite element model with the experimental studies, a parametric study were conducted on the steel...
Experimental Investigations into Damage Detection Techniques in Concrete Beams
, M.Sc. Thesis Sharif University of Technology ; Joghataie, Abdolreza (Supervisor)
Abstract
A simply supported reinforced concrete beam has been built at the concrete laboratory of Sharif University of Technology. The cross section of the beam has been rectangular and all the reinforcing steel bars have been placed at the bottom of the beam. A progressive damage has been applied to the beam first by cutting the concrete cover and then by cutting the reinforcing bars one at a time. The beam has been tested using forced vibration test where an impact hammer has been used to apply the external load. The acceleration of the beam has been recorded based on which the FRFs and then the corresponding modal parameters have been determined. Finally natural frequencies, MAC, COMAC and mode...
Flexural Behavior of Concrete Beams Reinforced with High Volume Steel Fibers
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Alireza (Supervisor)
Abstract
In recent years, the use of fibers has found considerable attention in concrete structures as in spillways, basins of dams, shell structure, industrial floors, and bridge pedestrians. Fibers modify the brittle nature of concrete and make the composite behave ductile under various types of loading. Fibers have numerous advantages such as higher impact resistance, less shrinkage, smaller crack width, higher durability and low expense for repair and maintenance.
Till now, no adequate data has been reported on concrete beams reinforced with high volume fiber. In this study, flexural behavior of concrete beams reinforced with high volume steel fibers is experimentally investigated. Concrete...
Till now, no adequate data has been reported on concrete beams reinforced with high volume fiber. In this study, flexural behavior of concrete beams reinforced with high volume steel fibers is experimentally investigated. Concrete...
Investigating The Seismic Performance of R/C Buildings Equipped With Shape Memory Alloy Braces
, M.Sc. Thesis Sharif University of Technology ; Rahimzadeh Rofooei, Fayyaz (Supervisor)
Abstract
Shape memory alloys (SMAs) are metallic materials that have unique properties, including shape memory effects, superelastic effects, and high damping characteristics. Recovery of large deformation and capability of energy dissipation during mechanical loading-unloading cycles are special properties of superelastic effect of shape memory alloys. Due to these distinctive macroscopic behaviors, not present in most traditional materials, SMAs are the basis for innovative applications like devices for protecting buildings from structural vibrations. This paper presents a numerical investigation aimed at evaluating the improvements achievable through devices for passive seismic protection of...
Parametric Study on Seismic Performance of Spherical RC Domes
, M.Sc. Thesis Sharif University of Technology ; Vafaei, Abolhassan (Supervisor) ; Mofid, Massoud (Co-Advisor)
Abstract
The present parametric study discusses the effective factors on seismic performance of spherical RC domes. For this perpose, a series of domes with different spans, a variety of contact angles (the angle between the bottom of the sphere and the center of the sphere), openings with different areas and various support condition are studied. Then the value of response modification factor and it's components is determined to take into account the effect of each component. The results obtained indicated that the response modification factor increases as the contact angle enhances. However, the span of domes insignificantly affects the value of response modification factor.also analysis on domes...
On the Characteristics and Performance of RCFrames with Y-Bracing Systems
, M.Sc. Thesis Sharif University of Technology ; Mofid, Masood (Supervisor)
Abstract
Steel bracing systems can be used effectively for seismic retrofitting of existing RC buildings as well as for seismic design of new building. Steel bracing system has been used to increase the lateral load resistance of steel structures. In recent years the concept of steel bracing has also been applied to the retrofitting of reinforced concrete frames, especially to improve seismic performance of non-ductile reinforced concrete buildings. The use of steel bracing systems for seismic rehabilitation of RC frames offers some advantages such as (a) minimal added weight to the structure; (b) ease and speed of construction;(c) increased architectural flexibility; in comparison with RC shear...
Evaluation of Seismic Criteria and Random Parameters on Fragility Curves of RC Frames
, Ph.D. Dissertation Sharif University of Technology ; Bakhshi, Ali (Supervisor)
Abstract
There are many parameters which are utilized to obtain a more reasonable performance for structures under earthquake excitations in seismic provisions. It is well recognized that the main character to design of structures under seismic excitation is probabilistic rather than deterministic; therefore, it should be determined if the probability of structural damages is decreased when such parameters change in design of structures. In this thesis, fragility curves are developed in order to evaluate these parameters. Fragility curves are employed for various probability parameters. These diagrams are utilized to demonstrate when a coefficient or a number of parameters are used to improve...
Performance of RC Shear Walls Strengthened by Vertical Strips of Steel Plates under Seismic Loading
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Alireza (Supervisor)
Abstract
Even though a considerable amount of research has been conducted on composite wall system during past years, very limited research has been reported on shear walls strengthened by steel plates. In 2008, the composite shear wall, which consisted of reinforced concrete wall, retrofitted by steel plates, attached to both sides of RC walls using mechanical connectors in form of shear studs, bolts or lateral ties tested under axial load and lateral force. In this research, seismic behavior of RC shear walls strengthened by vertical strips of steel plates is going to be studied. The result will be compared with RC shear wall which fully covered by steel plates. The behavior of RC shear wall will...