Loading...
Search for:
reinforced-concrete
0.008 seconds
Total 195 records
Behavior of channel shear connectors, Part II: Analytical study
, Article Journal of Constructional Steel Research ; Volume 64, Issue 12 , December , 2008 , Pages 1341-1348 ; 0143974X (ISSN) ; Bagheri, S ; Sharif University of Technology
2008
Abstract
In this second part of the two companion papers an effective numerical model is proposed using finite element method to simulate the push-out test of channel shear connectors. The focus is on the shear capacity of channel shear connectors embedded in a solid reinforced concrete slab under monotonic loading. The model has been validated against test results presented in Part (I) and compared with data given in North American design codes. Parametric studies using this nonlinear model are performed to investigate the variations in concrete strength, channel dimensions and the orientation of the channel. The results show that the concrete strength, web and flange thicknesses of the channel and...
Seismic behavior comparison of RC shear walls strengthened using FRP composites and steel elements
, Article Scientia Iranica ; Volume 28, Issue 3 A , 2021 , Pages 1-27 ; 10263098 (ISSN) ; Khaloo, A ; Abdoos, H ; Sharif University of Technology
Sharif University of Technology
2021
Abstract
This paper aims at investigating the seismic behavior of strengthened reinforced concrete (RC) shear walls using a 3D finite element analysis. A series of four different configurations of carbon fiber reinforced polymer (CFRP) composites and four different schemes of steel elements are utilized to compare the two methods of retrofitting RC shear walls with similar dimensions and reinforcement ratios. Nonlinear simulations of the RC shear walls are conducted under the action of lateral cyclic loading in ABAQUS Explicit software. In addition, the numerical modeling for RC walls strengthened by CFRP composites as well as steel elements are validated according to the previous experimental...
Prediction of the degree of steel corrosion damage in reinforced concrete using field-based data by multi-gene genetic programming approach
, Article Soft Computing ; Volume 26, Issue 18 , 2022 , Pages 9481-9496 ; 14327643 (ISSN) ; Eftekhari, M ; Ghorbani, M ; Ehteshamzadeh, M ; Beirami, H ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2022
Abstract
Unanticipated failure of reinforced concrete structures due to corrosion of steel rebar embedded in concrete causes to increase the demand for finding methods to forecast the service life of concrete structures. In this field, the success of machine learning-based methods leads to the use of multi-gene genetic programming (MGGP) method for classifying the degree of corrosion destruction of steel in reinforced concrete in this paper. Despite the common application of MGGP that is the symbolic regression, in this research, MGGP was adapted to use in classification tasks. Accordingly, a large field database has been collected from different regions in the Persian Gulf for modeling of MGGP and...
Machine learning-aided scenario-based seismic drift measurement for RC moment frames using visual features of surface damage
, Article Measurement: Journal of the International Measurement Confederation ; Volume 205 , 2022 ; 02632241 (ISSN) ; Mansourdehghan, S ; Asjodi, A. H ; Dolatshahi, K.M ; Sharif University of Technology
Elsevier B.V
2022
Abstract
This paper presents a novel computer vision-based methodology for assessment of the seismic damage in reinforced concrete moment frames using visual characteristics of surface damage following an earthquake. An extensive collected database comprising 974 images associated with 256 cyclic-loaded damaged beam-column joints, providing a set of cracking and crushing progression with increasing the evolution of damage level, is collected and used for the development and validation of the methodology. Employing image processing techniques, the characteristics of the surface damage, including the cracking length and crushing areas, are measured and used in a scenario-based assessment for the...
Peak drift ratio estimation for RC moment frames using multifractal dimensions of surface crack patterns
, Article Engineering Structures ; Volume 255 , 2022 ; 01410296 (ISSN) ; Ganjizadeh, A ; Dolatshahi, K. M ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
In this paper, a novel computer-vision based methodology is developed for predicting the seismic peak drift ratio of damaged reinforced concrete moment frames using surface crack patterns. A comprehensive database comprising 974 surface crack images from cyclic test results of 256 beam-column joint specimens at various drift ratio levels is collected. The database covers a broad range of concrete compressive strengths, rebar and stirrup strengths, longitudinal and transverse reinforcement ratios, beam and column length to depth ratios, in-plane configurations, and failure modes. Multifractal dimensions of damaged beam-column subassembly images are obtained by the box-counting algorithm to...
Experimental and numerical investigation of minimum required fiber content in bending characteristics of 100 MPa UHPC-formulated concrete
, Article Case Studies in Construction Materials ; Volume 16 , 2022 ; 22145095 (ISSN) ; Khaloo, A ; Hassanpour, S ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
The present study investigates the lowest possible amount of steel and polypropylene fibers in improving the compressive and flexural strength, stiffness, and energy capacity of high strength 100 MPa concrete with a mix design similar to that of Ultra-High Performance Concrete (UHPC). Twenty-eight 100 × 200 mm cylindrical specimens with 0%, 0.2%, 0.4%, and 0.6% volumetric percentage of short steel fibers and polypropylene fibers were fabricated, which were at the lowest predicted percentages with respect to fiber content recommended in the literature. To assess the flexural performance of fiber-reinforced concrete panels, specimens with dimensions of 200 × 600 × 20 mm were made with the same...
Fiber bridging in polypropylene-reinforced high-strength concrete: An experimental and numerical survey
, Article Structural Concrete ; Volume 23, Issue 1 , 2022 , Pages 457-472 ; 14644177 (ISSN) ; Daneshyar, A ; Rezaei, B ; Fartash, A ; Sharif University of Technology
John Wiley and Sons Inc
2022
Abstract
Fracture process of fiber-reinforced concrete notched beams is investigated here. Polypropylene macrosynthetic fibers are utilized for reinforcing concrete specimens, and a high-strength mix design is used to produce strong bonds between the embossed polypropylene fibers and the cementitious matrix of beams. Considering different locations for the notch, this study focuses on bridging mechanism under different conditions using both experimental and numerical approaches. First mode of fracture occurs due to opening of crack faces. This mode of failure is simulated by imposing symmetric boundary conditions on middle-notched beams. Inducing the notch with an offset from the middle, mixed-mode...
, M.Sc. Thesis Sharif University of Technology ; Moghaddam, Hassan (Supervisor)
Abstract
The observed response of medium rise buildings during sever earthquakes worldwide has indicated that RC buildings with shear walls behave considerably better than other buildings. The conviction that shear walls are inherently brittle still prevails amongst engineers, and therefore, they usually prefer to choose moment resisting RC frames without shear walls. In this study, a number of RC frames, with and without shear walls are designed in accordance with the seismic codes, and are then subjected to an assemble of severe earthquakes. The results of timehistory nonlinear analyses of these models are then used to investigate the effect of the presence of shear walls within the framework of...
Seismic Behavior of Reinforced Concrete Frames Retrofitted by Pre-Stressed Steel Strips
, M.Sc. Thesis Sharif University of Technology ; Moghaddam, Hassan (Supervisor)
Abstract
With occurring severe earthquakes, damages of columns in RC buildings can lead to overall failure and collapse. So retrofitting of such columns that do not comply with the design requirements is necessary to prevent such phenomena. A variety of methods has been introduced so far for retrofitting. The key factors in determining the retrofitting methods are being economic and easily implemented in the design. Confining concrete columns with pre-stressed steel strips is a new technique that is simple and economic. Previous experimental experiments have shown that this method can enhance ductility and overall seismic behavior of such columns.
In the present study three and six story frames...
In the present study three and six story frames...
Seismic Performance of Composite Frames Consisting of Reinforced Concrete Columns and Steel Beams
, M.Sc. Thesis Sharif University of Technology ; Kazemi, Mohammad Taghi (Supervisor)
Abstract
Composite systems consisting of concrete columns and steel beams are introduces as structural systems in recent years. These structural systems enjoy merits of both steel and concrete frames by efficiently combining the advantages of them. This study is allocated to lateral force resistance system using armed concrete and structural steel. Advantages of composite structures rather to those of two other conventional ones are among performance characteristics under ultimate loads, economical conservation, and higher speed of construction.In this research the aim is to study these frame under earthquake induced loads. The seismic performances of these composite frames with through column beams,...
Effects of Thickness and Compressive Strength on The Behavior of Corrugated Fiber-Reinforced Concrete Shear Wall in a Steel Frame
, M.Sc. Thesis Sharif University of Technology ; Mofid, Massoud (Supervisor)
Abstract
Seismic loads are still a challenge for structures and engineers invent and provide seismic resisting systems to resist better against it. Concrete shear walls are well-known seismic resisting system that has had an acceptable performance in occurred seismic events. This system costs noticeable amount of time and material. Fiber-reinforced concretes can be useful to reduce negative effects and provides more positive effects like tensile strength, ductility, impact resisting and etc. Also changes in wall appearance such as corrugating helps to improve shear wall performance as it improves other kinds of plates and shell shaped members in structures. In this thesis, the focus is on “corrugated...
Response Evaluation of Reinforced Concrete Frames Designed for Earthquake Subjected to Blast Loading
, M.Sc. Thesis Sharif University of Technology ; Kazemi, Mohammad Taghi (Supervisor)
Abstract
Explosion as a physical phenomenon have various effects on the environment, including living organisms, surrounding buildings, equipment and infrastructure there. Due to such extreme loading conditions, efforts have been made during the past three decades to develop methods of structural analysis and design to resist blast loads. The analysis and design of structures subjected to blast loads require a detailed understanding of blast phenomena and the dynamic response of various structural elements. The most appropriate method for evaluating the behavior of structures under blast loading is performance approach which specifies the response of structures against explosion. It seems that...
Retrofit and Design of Concrete Beams by Using Active Tendons
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Alireza (Supervisor)
Abstract
Structural elements are exposed to different types of loading which may cause excessive deformations during their life cycle. These deflections may cause damage to the structure .Therefore; reduction of dynamic response of structures can be achieved by exploiting active control system.
In this research, the dynamic behavior of prestressed Eulthemer Bernollli concrete beam under moving Load, support excitation and multi support excitation, controlled by active tendon is studied.The control algorithm employed in this thesis is closed loop linear classical optimal control with displacement-velocity feedback. R and Q matrices are chosen in order to balance the source energy consumption and...
In this research, the dynamic behavior of prestressed Eulthemer Bernollli concrete beam under moving Load, support excitation and multi support excitation, controlled by active tendon is studied.The control algorithm employed in this thesis is closed loop linear classical optimal control with displacement-velocity feedback. R and Q matrices are chosen in order to balance the source energy consumption and...
Damage Assessment of Reinforced Concrete Shear walls Using Crack Pattern
, M.Sc. Thesis Sharif University of Technology ; Mohtasham Dolatshahi, Kiarash (Supervisor)
Abstract
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...
Life Cycle Cost Analysis and Comparison Of Concrete Structures with and Without Shear Walls by Endurance Time Method
, M.Sc. Thesis Sharif University of Technology ; Esmaeilpour Estekanchi, Homayun (Supervisor)
Abstract
The actual value of structures should not be evaluated only based on initial cost, because failure cost and economical losses due to corrosion and natural hazards can be catastrophic. When a long life Performance of a structure is expected, life cycle cost analysis is the best way to assess and compare economic value of different design choices. The main purpose of this work is investigating the effect of shear walls in limit state cost and total cost . Results demonstrate that shear walls can reduce limit state cost up to 70 percent . Furthermore the influence of increasing thickness of shear walls and effect of reducing dead loads in total life cycle cost is discussed. It is shown that...
A Strain Rate Constitutive Model for Fiber Reinforced Concrete Based on Split Hopkinson Pressure Bar Tests
, Ph.D. Dissertation Sharif University of Technology ; Naghdababi, Reza (Supervisor)
Abstract
In this thesis, experimental and numerical investigations are performed on dynamic behavior of fiber reinforced concrete (FRC) by split Hopkinson pressure bar (SHPB) and penetration tests. In the experimental part, effects of parameters such as quasi-static compressive strength of matrix (36 and 48 MPa), strain rate (3*10-5 up to 100 s-1), type of fibers (crimped steel, hooked-end steel, micro polypropylene and micro polypropylene) and volume fraction of the fibers (0%, 1% and 2%) are studied by employing SHPB apparatus on testing more than 150 specimens. Also, different types of FRC panels with 5 cm thickness were casted to perform 20 penetration tests with compressed gas gun apparatus. The...
Analysis of RC Structural Frames Strengthened by Steel Bracing
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Alireza (Supervisor)
Abstract
Concentric steel braces and brace-type dampers are often applied to the upgrading of reinforced concrete frames subjected to lateral loads. These braces may develop High axial tension forces, and transferring them appropriately to the existing beam– Column joints is a key challenge. This paper investigates a solution for connecting the end-plate of the steel brace with the frame, using shear-key plates fixed to the concrete with anchor bolts, and a low friction material inserted between the end-plates and the shear-key plates. The presence of the low friction material impedes the development of tension forces in the anchor bolts and ensures that they are basically subjected to shear forces....
Experimental Investigations on RC Arches Strengthened Using GFRP Sheets
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Alireza (Supervisor)
Abstract
A total of twenty-four reinforced concrete arches with dimensions of 110 × 30 × 10 cm were casted, fabricated and tested. There are three variables, including: height to span ratio, longitudinal reinforcement ratio and arrangement and number of FRP layers.Based on results, with increasing height to span ratio, the efficiency of FRP strengthening method decreases. It is due to the fact that FRP materials inherently behave better in tension. From another point of view, in lower arches (L group) extrados bonding technic has better effect on increasing peak load of the arches, while in higher ones (H group) intrados bonding is discerned as the best method of strengthening. This paradoxical...
Flexural Strengthening of Reinforced Concrete Beams by FRP Composites to Reduce Creep Deflection
, M.Sc. Thesis Sharif University of Technology ; Kazemi, Mohammad Taqhi (Supervisor)
Abstract
The strengthening of reinforced concrete structures with externally bonded fibre reinforced polymer (FRP) laminates has shown excellent performance, so this technology is rapidly replacing externally bonded steel plates, steel or concrete jackets, and many traditional techniques available. In this study strengthening of reinforced concrete beams by GFRP to reduce creep deflection is investigated by mathematical method using available relations. Five RC beams with different dimensions, with and without strengthening with GFRP laminate, were investigated for their creep deflection. The creep coefficient of beams selected from experimental result that were mentioned in RILEM DATA BANK. In this...
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...