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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...
Experimental investigation of mechanical behavior and microstructural analysis of bagasse fiber-reinforced polypropylene (BFRP) composites to control lost circulation in water-based drilling mud
, Article Journal of Natural Gas Science and Engineering ; Volume 100 , 2022 ; 18755100 (ISSN) ; Jafari Behbahani, T ; Ghotbi, C ; Nasiri, A ; Sharif University of Technology
Elsevier B.V
2022
Abstract
During the drilling operation in high-permeability, natural and artificial fractured formations, the lost circulation of drilling mud is a common problem. Various methods have been applied to control lost circulation and among these methods, using Lost Circulation Materials (LCM) is the most common method that blocks the fluid loss channels in the formation by creating structures. In this project, the aim is to develop and use natural fiber-reinforced composites as LCM can be an innovative and technical solution. Natural fiber-reinforced composites have excellent properties such as high specific strength, non-abrasive, eco-friendly, and biodegradability. It seems to be possible that...
Effect of compressive glass fiber-reinforced polymer bars on flexural performance of reinforced concrete beams
, Article ACI Structural Journal ; Volume 119, Issue 6 , 2022 , Pages 5-18 ; 08893241 (ISSN) ; Khaloo, A ; Aliasghar Mamaghani, M ; Khaloo, H ; Sharif University of Technology
American Concrete Institute
2022
Abstract
This research studies the effect of glass fiber-reinforced polymer (GFRP) bars as compressive reinforcement in reinforced concrete (RC) beam members. Three singly and six doubly reinforced GFRP-RC beams were tested under a four-point loading configuration. The effect of compressive reinforcement on the load-bearing capacity, ductility, stiffness, and failure mode is determined. Also, the compressive performance of GFRP bars is evaluated by testing GFRP-RC cylinders. According to the results, GFRP bars in compression had a limited contribution to enhancing flexural strength, and the maximum increment in the flexural capacity of doubly reinforced beams compared to singly reinforced specimens...
Investigation on Seismic Behavior of Old Masonry Structure (A case study of Daniel historical sanctuary)
, M.Sc. Thesis Sharif University of Technology ; Khalou, Alireza (Supervisor)
Abstract
Masonry structures are complex systems that require a thorough and detailed knowledge for analysis and designing, and especially maintaining their capability. Since the old historical masonry structures have cultural value, maintenance of such structures against natural disasters that cause destruction is important. The goal of this research is to find a method for protection of the historical masonry structure of Daniel shrine that is located in susa region in Khuzestan. According to the reference structures of architectural heritage, a number of challenges in conservation, diagnosis, analysis, monitoring, repair and strengthening are presented that limit the application of modern codes...
Behavior Evaluation of Pre-stressed Concrete Slabs Strengthened by FRP laminates under Impact Loads
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Alireza (Supervisor)
Abstract
The investigation of non-prestressed concrete components subjected to impact loadings has been reported in the literature. However, the knowledge on the impact-resistant capacity of pre-stressed concrete components is very limited. In this study, behavior of pre-stressed concrete slabs strengthened by FRP sheets is investigated. The behavior of strengthened pre-stressed concrete slabs under impact load is analyzed using finite elements method. The effects of FRP strengthening of pre-stressed concrete slabs to resist impact loads have been studied using ANSYS software. Pre-stressed concrete slabs have been modeled without/with different FRP strengthening measures. Pre-stressed concrete slab...
Behavior Evaluation of Reinforced Concrete Slabs Strengthened by FRP laminates under Impact Loads
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Alireza (Supervisor)
Abstract
Precise numerical models to predict responses and damage of FRP strengthened RC slabs to impact loads are limited in the literature. The behavior of (RC) slabs strengthened by FRP sheets is investigated. The behavior of strengthened RC slabs under impact load is analyzed using finite elements method. In this study, the effects of FRP strengthening of RC slabs to resist impact loads have been performed using ANSYS software. RC slabs without/with different FRP strengthening measures have been simulated in this study. RC slab without strengthening and RC slab strengthened with FRP sheets applied to the tension face of the slab have been included in the model. Each slab is subjected to repeated...
Strengthening RC Arch Structures Using FRP Laminate
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Alireza (Supervisor) ; Kazemi, Mohammad Taghi (Supervisor)
Abstract
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...
Evaluation of Strengthening Methods for Concrete Shear Walls
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Alireza (Supervisor) ; Kazemi, Mohammad Taghi (Supervisor)
Abstract
The purpose of this study is to determine the effects of some strengthening methods such as steel jacketing, concrete jacketing and FRP wraps in the overall behavior of structures and introducing the most appropriate method. For this purpose a 14 story building with intentionally weak designed shear walls was considered, subsequently each of the strengthening methods were followed for the shear walls and relative structural outcomes like total stiffness and lateral movements were calculated, studied and compared and finally a guideline for choosing the most appropriate strengthening method for concrete shear walls is resulted. It is established that for the system with steel jacketing...
A Finite Element Study on Seismic Behavior of Various Concrete Column Retrofitting Methods
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Alireza (Supervisor)
Abstract
In recent years, in order to investigate the structural performance in seismic zones, concrete column reinforcement and observing their behavior under cyclic loading have attracted considerable attentions. The ductility and energy absorption capability of structure play an important role in structural performance against earthquake and consequently its failure patterns. A new chapter of these investigations has begun by the reinforcement of the concrete members, a major part of which is concerned with the confinement of concrete members in order to increase their ductility and energy absorption against the forces induced by earthquake. In this study, three prominent methods of concrete...
Seismic Performance Evaluation of RC Frames Rehabilitated by Different Techniques Using IDA
, M.Sc. Thesis Sharif University of Technology ; Khalu, Alireza (Supervisor)
Abstract
Seismic behavior of multi-story frames widely has been studied in recently. So that such studies can lead the earthquakes-resistance system to better performance. The dramatic growth of computer processing power make it possible that nonlinear dynamic analysis of structures with great precision could be done. One of the advantages of nonlinear analysis is achieve behavioral performance of structures during an earthquake. Knowledge of the performance, enables us to identify structural weaknesses result in devising to improve these. The aim of this study is to evaluate the seismic performance of reinforced concrete frames have been improved, using different techniques. The frames are designed...
Strengthening RC Slabs under Various Loads and Boundary Conditions Using FRP Composites
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Ali Reza (Supervisor)
Abstract
In recent decades the use of FRP materials for strengthening structures has been developed extensively, thanks to their high strength, sufficient stiffness, high durablity, and ease of use. A great deal of research has been conducted on strengthening reinforced concrete beams and columns with FRP composites. By contrast, not many researches are performed on slabs, especially two-way slabs. In these few researches, the loading and boundary conditions are limited to simplest ones. Therefore, in this thesis, the focus of attention is on strengthening reinforced concrete slabs under various loads and boundary conditions using FRP composites.
In this thesis, first, FRP composites and their...
In this thesis, first, FRP composites and their...
Numerical Analysis of Buried Pipelines Strengthened by FRP Subjected to Reverse Faulting
, M.Sc. Thesis Sharif University of Technology ; Rahimzadeh Rofooei, Fayaz (Supervisor)
Abstract
Buried pipes are among the most important urban infra-structures which are developed to distribute water, gas, oil, etc.. Researchers have already demonstrated that extreme failures which lead to total disruption of the pipelines, both mains and the distribution network, due to permanent ground displacement in fault zones. In order to avoid any disturbance in the regular performance of pipelines and prevention of environmental contamination, there is a need to investigate the vulnerability of pipelines and their seismic retrofitting, if necessary. In the presented study, the method of pipeline retrofitting by high strength CFRP composite is investigated. In that regard, using a 3D model of...
Performance Evaluation of Reinforced Concrete Bridge Deck Strengthened with FRP Laminates
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Alireza (Supervisor)
Abstract
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...
Improvement in Reinforced Concrete Beam-Column Connections Behaviour using FRP Sheets
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Alireza (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 the last decade Fiber Reinforced Polymer (FRP) widely has been used to strengthening the reinforced concrete (RC) members. Most of...
Effect if Strengthening of Continuous RC Beams with FRP Laminates on Moment Redistribution under Vertical Loads
, M.Sc. Thesis Sharif University of Technology ; Mostofinejad, Davoud (Supervisor)
Abstract
The continual deterioration and insufficient strength of reinforced concrete (RC) structures has been a vital problem in the field of civil engineering such an extent that traditional methods of strengthening found to be inconvenient. Nowadays by increasing demands for retrofitting of structures, it necessitates the application of efficient, inexpensive and unobtrusive methods of strengthening. Common way on retrofitting was to use of steel plates externally bonded to RC members. Although this technique has proven to be reasonably effective, it has several distinct disadvantages such as susceptibility of the steel plates to corrode and the excessive weight of steel plates when used in...
Transverse Retrofit of Infilled Frames with FRP
, M.Sc. Thesis Sharif University of Technology ; Moghaddam, Hassan (Supervisor)
Abstract
Masonry buildings are wide spread in Iran and some other countries . These buildings are highly vulnerable to seismic excitations if not constructed in accordance with engineering fundamentals . Thus it is necessary to retrofit these structures to flee from humanitarian and economical damages inflicted by earthquakes. One of the critical vulnerabilities of masonry buildings is due to transverse instability of it’s infills . Therefore to study out of plane behavior of these elements , an infilled frame is modeled and analyzed with ABAQUS , the results of which is in good congruence with the experimental one . In this model , stress distribution due to one way arching action in the confined...
Numerical Modeling of Shear Strengthening of Reinforced Concrete Deep Beams by Using FRP
, M.Sc. Thesis Sharif University of Technology ; Kazemi, Mohammad Taghi (Supervisor)
Abstract
The structural behavior of deep beams is different with usual beams as a result of the low span-to-height ratio. Shear failure load is less for deep beams. Implementation of externally bonded reinforcement such as fiber reinforced polymers (FRP) is a unique method for shear strengthening of deep beams. In this study, the effects of FRP layers on the web of the reinforced concrete deep beam have been investigated by a nonlinear finite element program. Five beams four of which were strengthened with FRP laminates were numerically modeled and the results were compared with experimental results. The effect of some governing parameters such as compressive strength of concrete, orientation of...
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...
Strengthening Reinforced Concrete Deep Beams Using FRP Systems
, M.Sc. Thesis Sharif University of Technology ; Kazemi, Mohammad Taghi (Supervisor)
Abstract
In recent years, the development of the plate bonding repair technique has been shown to be applicable to many existing strengthening problems in the building industry. This technique may be defined as one in which composite sheets or plates of relatively small thickness are bonded with an epoxy adhesive to, in most cases, a concrete structure to improve its structural behaviour and strength. The sheets or plates do not require much space and give a composite action between the adherents. The old structure and the new bonded-on material create a new structural element that has a higher strength and stiffness than original one. According to the available methods of analysis and design for...
On the Seismic Behavior of RC Frames with Brick Infilled Walls with Opening, Retrofitted by FRP
, M.Sc. Thesis Sharif University of Technology ; Rahimzadeh Rofooei, Fayaz (Supervisor)
Abstract
Wall systems are an essential part of the buildings and their capacity should be properly considered in their design. However, the seismic behavior of building systems with in-filled walls and their interaction is a very complex issue, yet to be understood. Using the in-filled walls in the buildings without including them in the design process changes the whole behavior of the structural system as well as their failure mechanism under earthquake excitations. On the other hand, there have been extensive researches on rehabilitation of the structures with in-filled walls or designing them as the main or one of the lateral load carrying systems against seismic input. In this research, first the...