Top PDF Simulation of the Behavior of Corrosion Damaged Reinforced Concrete Beams with/without CFRP Retrofit

Simulation of the Behavior of Corrosion Damaged Reinforced Concrete Beams with/without CFRP Retrofit

Simulation of the Behavior of Corrosion Damaged Reinforced Concrete Beams with/without CFRP Retrofit

In this research, the first corrosion impairment has been put away from consideration. Ordinary concrete exhibits relatively negligible tensile strength. Therefore, cracking of tensile steel reinforcements induced by corrosion of tensile reinforcements does not considerably influence the structural behavior of reinforced concrete beams [5]. Thus, the second and third items of above list are taken into account in steel reinforcement corrosion simulations conducted in the current study. Several experimental investigations have been demonstrated the effectiveness of CFRP retrofit to restore the loss of flexural strength of corrosion damaged reinforced concrete beams [6]. CFRP retrofit is widely used and the effectiveness increased by several modifications [7]. Moreover, an extensive research has been carried out at University of Waterloo under different loading regimes and conditions [8], which further strengthened the significance of CFRP retrofit for corroded reinforced concrete members. More recently, Lingga conducted an experimental study on six reinforced concrete beams, which shows the efficiency of CFRP to retrofit corrosion damaged reinforced concrete beams [9]. Moghadam et al. reported one of the first numerical studies on the behavior of corrosion damaged reinforced concrete beams retrofitted with CFRP sheet. However, the influence of corrosion on the bond between the steel and concrete is not taken into account in their study [10]. Recent studies concentrated on improving the accuracy of this approach to increasing the efficiency of CFRP to retrofit corrosion damaged reinforced concrete in tidal zone [11]. The effect of materials on the reliability of reinforced concrete beams in normal and intense corrosion, is widely investigated on supplementary research [12]. The efficiency of Finite element ABAQUS software in numerical modeling was illustrated in several studies [13]. Development of a numerical model for the behavior of concrete is a challenging task. Concrete is a brittle material in tension and has different behavior in compression and tension. ABAQUS demonstrated the reliable numerical results and the result of the concrete modeling has been verified [14].
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Simulation of the Behavior of Corrosion Damaged Reinforced Concrete Beams with/without CFRP Retrofit

Simulation of the Behavior of Corrosion Damaged Reinforced Concrete Beams with/without CFRP Retrofit

In this research, the first corrosion impairment has been put away from consideration. Ordinary concrete exhibits relatively negligible tensile strength. Therefore, cracking of tensile steel reinforcements induced by corrosion of tensile reinforcements does not considerably influence the structural behavior of reinforced concrete beams [5]. Thus, the second and third items of above list are taken into account in steel reinforcement corrosion simulations conducted in the current study. Several experimental investigations have been demonstrated the effectiveness of CFRP retrofit to restore the loss of flexural strength of corrosion damaged reinforced concrete beams [6]. CFRP retrofit is widely used and the effectiveness increased by several modifications [7]. Moreover, an extensive research has been carried out at University of Waterloo under different loading regimes and conditions [8], which further strengthened the significance of CFRP retrofit for corroded reinforced concrete members. More recently, Lingga conducted an experimental study on six reinforced concrete beams, which shows the efficiency of CFRP to retrofit corrosion damaged reinforced concrete beams [9]. Moghadam et al. reported one of the first numerical studies on the behavior of corrosion damaged reinforced concrete beams retrofitted with CFRP sheet. However, the influence of corrosion on the bond between the steel and concrete is not taken into account in their study [10]. Recent studies concentrated on improving the accuracy of this approach to increasing the efficiency of CFRP to retrofit corrosion damaged reinforced concrete in tidal zone [11]. The effect of materials on the reliability of reinforced concrete beams in normal and intense corrosion, is widely investigated on supplementary research [12]. The efficiency of Finite element ABAQUS software in numerical modeling was illustrated in several studies [13]. Development of a numerical model for the behavior of concrete is a challenging task. Concrete is a brittle material in tension and has different behavior in compression and tension. ABAQUS demonstrated the reliable numerical results and the result of the concrete modeling has been verified [14].
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Fatigue Behaviour of CFRP Strengthened Reinforced Concrete Beams

Fatigue Behaviour of CFRP Strengthened Reinforced Concrete Beams

Fatigue testing of the specimens was conducted at stress ranges proportional to their static failure loads. It was found that the ultimate failure loads reduced as the damage extent of the specimen increased from 450mm to 1800mm, where the 450mm specimen failed at 325kN and the 1800mm specimen failed at 290kN. The 0mm specimen had the lowest static failure load despite it not being corrosion damaged nor patch repaired. In contrast, the fatigue lives of the specimens showed an inverse relationship to their static failure loads, where the 0mm specimen had the highest fatigue life. The results showed that as the damage extent was increased from 450mm to 1800mm the fatigue life increased by 106.3% under the 60% stress range tests. Under the 40% stress range the fatigue life increased considerably as well, though the exact increase could not be determined, because the 1800mm specimen test was terminated at 2 000 000 cycles after not failing due to fatigue. Three out of five fatigue specimens tested under the 40% stress range were terminated after not failing due to fatigue, but the two specimens that did fail showed that the specimen with a longer damage extent achieved a longer fatigue life. Furthermore, the experimentally obtained fatigue lives were compared to three fatigue life prediction models suitable for CFRP strengthened RC beams and although all three models yielded fatigue life predictions similar to the experimental results, the fatigue life cycles predicted by the Helgason and Hanson model (Zorn, 2006) yielded the closest correlation with the experimental results. Moreover, it was noted that the specimens with the longer corrosion damage and patch repair extents yielded a post-fatigue life in the order of 75% lower than the specimens with the shorter damage extents.
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Fundamental Behavior of Steel-Concrete Composite Beams Strengthened with High Modulus Carbon Fiber Reinforced Polymer (CFRP) Materials

Fundamental Behavior of Steel-Concrete Composite Beams Strengthened with High Modulus Carbon Fiber Reinforced Polymer (CFRP) Materials

Investigation into the repair of cracks by application of a composite patch began in the aerospace and marine industries for the repair of aircraft skins and ship hulls. In one study side notched aluminum alloy tension coupons were repaired using a boron/epoxy tape and tested in fatigue to simulate the repair of an aircraft structure (Baker, 1987). Patching effectively reduced the crack growth rates for specimens with a long initial crack, but not for specimens with a short initial crack. Some local delamination was observed near the patch location but this did not induce failure of the specimens. In another investigation, aluminum alloy tension coupons were reinforced with steel and CFRP patches (Allan et al., 1988). The coupons consisted of two plates which were butted together, some of which were welded together and others which remained unwelded. Testing demonstrated that application of a reverse taper to the end of the patch increased the fatigue life of the repair by a factor of four. The success of crack repair in these two fields shows promise for the retrofit of steel bridges using CFRP materials.
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Behaviour of Reinforced Concrete Beams Strengthened by CFRP Wraps

Behaviour of Reinforced Concrete Beams Strengthened by CFRP Wraps

A structure is designed for a specific period and depending on the nature of the structure and surrounding environment, its life varies. Depending on usage of structure life of the structure are decided. During the life span of structural deterioration happens. The deterioration can be mainly due to environmental effects, which includes corrosion of steel, gradual loss of strength with ageing, repeated high intensity loading, variation in temperature, freeze-thaw cycles, contact with chemicals and saline water and exposure to ultra-violet radiations. Now to compensate deterioration, structure should be either replaced or properly retrofitted. As complete replacement or reconstruction of the structure costs very high compared to strengthening or retrofitting, so generally it is preferred to retrofit or strengthened the structure.
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Ultimate Flexural Capacity of Reinforced Concrete Elements Damaged by Corrosion

Ultimate Flexural Capacity of Reinforced Concrete Elements Damaged by Corrosion

Among the main contributions analyzing the flexural behavior of corroded beams, the works of Rodriquez et al. [26-30] must firstly mentioned. The experimental results show that the collapse is caused by the steel failure accompanied by a significant concrete cracking for low reinforcement amount, while high reinforcement amount the is due to concrete crushing and buckling accompanied by a considerable ductility reduction. Capozucca [31] observes a 45% strength reduction for a 13% diameter reduction, while Mangat and Elgarf [32] state a 25% strength reduction for a 9.5% corrosion level, a reduction in terms of ultimate displacement and stiffness and a variation of the failure mode. Analyzing the global behavior of naturally corroded beams, Castel [33] highlights significant increasing of the maximum displacement and stiffness and ductility reduction. Moreover: Torres- Acosta [34] shows that the 20% corrosion level causes about the 60% flexural strength decay; Azad [35] confirms the increasing of deformation as a consequence of the corrosion; Zhang [36] relates the pitting corrosion development with the ultimate capacity and the bending stiffness reduction, that is the more sensitive parameter due to the steel–concrete bond loss. According to the latter, Du [37] experimentally finds that under the same loads, the time-dependent deflections of corroded beams increased more rapidly than those of non-corroded beam, and reached their limiting deflections prematurely. Other researches [38-40] evaluate the flexural strength degradation on reinforced concrete beams subjected to various different levels of chloride-induced reinforcing corrosion, finding that the failure mode can change from ductile to brittle when corrosion occurs.
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Flexural Behavior of Reinforced Concrete Strengthened With CFRP Sheets

Flexural Behavior of Reinforced Concrete Strengthened With CFRP Sheets

Weak structures whose capacity is insufficient, or for repairing damaged structures, has many advantages compared to conventional methods. The Canadian Armed Forces, with operations overseas in support of the United Nations, sees the potential of this technology as a fast and effective method of increasing the capacity of existing roadway bridges or buildings; Four point bending flexural test are conducted on four concrete control beams with externally bonded carbon fibre reinforced polymer sheets/ fabric. The effectiveness of externally bonded CFRP on the flexural strength of the concrete beam is studied
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Retrofit of Reinforced Concrete Deep Beams with Different Shear Reinforcement by Using CFRP

Retrofit of Reinforced Concrete Deep Beams with Different Shear Reinforcement by Using CFRP

The purpose of this paper is to study the experimental behavior and efficiency for retrofitted of reinforced concrete deep beams by carbon fiber reinforced polymer sheets, CFRP. An experimental program was conducted to retrofit nine failed deep beams by external CFRP sheets. Horizontal and vertical transverse reinforcement and shear span to depth ratios, were the main studied parameters in this paper. It was concluded that using this retrofitted method is very efficient and a gain in the ultimate load capacity of the deep beams was obtained. This gain was due to the efficiency of the external carbon fiber sheets to resist an extra applied load after failure. The failure in most of the retrofitted specimens was due to separate carbon fiber sheets from concrete or due to concrete crushing.
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A study of shear behavior of reinforced concrete deep beams

A study of shear behavior of reinforced concrete deep beams

beams with concentrated loads within twice the member depth from the support that are loaded on one face and supported on the opposite face so that compression struts can develop between the loads and supports. The shear behavior of deep beam is considerable different from that of slender beams that exceed the limits noted above. The assumptions of plane sections in analysis of normal beams can no longer be used for deep beams. The behavior of deep beams is dominated by shear deformation, thus in design of deep beam one needs a design procedure based on mechanisms of failure of deep beams. In practice, one typically encounters deep beams when designing transfer girders in tall buildings, pile supported foundation, or bent caps in bridges. Prior to 1999, ACI Code 318 included a design equation for designing reinforced concrete deep beams, but since 2002, the strut and tie model and nonlinear analysis have been specified. The strut and tie model is a powerful tool for designing reinforced concrete structures, but it is a multiple-step, complex procedure. Using Strut-and-Tie models requires some structural design and analysis experience. For nonlinear analysis, one needs a computer and a nonlinear program. In addition, designers need some finite element method knowledge, basic theory for algorithm, and an understanding of the primary variables. It is the reason that many practical designers are not confident using either procedure.
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Shear Behavior of Reinforced Concrete Beams Using Hybrid Fibres

Shear Behavior of Reinforced Concrete Beams Using Hybrid Fibres

This research work presents the effect of fibers on high-vigor reinforced Concrete beams with and without fiber. The study parameters for the investigation included ultimate load, ultimate deflections, crack width, energy ductility and deflection ductility and the associated failure modes. In this study hooked end steel fiber of length 35mm with thickness of 0.6mm and polyolefin fiber of length 54mm with the size 1.22mm x0.732mm is utilized. The fibers were integrated in concrete at different volume fractions of 0.5%, and 1.0% with coalescence of steel- polyolefin at 80%-20%. The steel moulds of size 150mm x300mm cylinder, and 150mm x 200mm x2000mm beam, were habituated to cast the high vigor concrete specimens, and hybrid fiber reinforced concrete specimens. It consists of 3 cylinders for specimens for compression, 3 cylinder for splitting tensile vigor and 3 beams for shear vigor test for each volume fraction of hybrid fiber. The cast specimens were abstracted from the mould after 24 hours and sanctioned for remedying. Then the specimens were tested after 28 days remedying in the moist condition as per ASTM Codes. The test results of high-vigor hybrid fiber reinforced concrete beams were compared with high-vigor concrete beams [HSC] with no fibers. The test results show that the hybrid fiber content of 1.0% with80%-20% steel polyolefin coalesce exhibits better performance in terms of vigor, deformation, ductility and cracking characteristics.
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Hysteretic Behavior of Conventionally Reinforced Concrete Coupling Beams in Reinforced Concrete Coupled Shear Wall

Hysteretic Behavior of Conventionally Reinforced Concrete Coupling Beams in Reinforced Concrete Coupled Shear Wall

To resolve these construction difficulties, several alterna- tive construction details for RC short coupling beams have been considered, including rhombic reinforcement, diagonal reinforcement without transverse ties, bent-up reinforce- ment, double beams, and long and short dowel reinforce- ment layouts (Tegos and Penelis 1988; Tassios et al. 1996; Galano and Vignoli 2000; Hajyalikhan 2015). However, none of these construction details allows for performance that is equivalent to that of coupling beams strengthened with bundled diagonal reinforcements according to the existing details specified in the standards and that signifi- cantly improve constructability. Recently, as the building design concept has changed to performance-based design, improving constructability and reducing economic costs have been accomplished by utilizing coupling beams with proper reinforcement details that are based on the required deformation capacity under the design loads rather than based on the aspect ratio, as in the current standard.
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Retrofit Design of Damaged Prestressed Concrete Cylinder Pipes

Retrofit Design of Damaged Prestressed Concrete Cylinder Pipes

Replacing the entire existing PCCP with partial damages is not a cost effective way, so a few rehabilitation methods have been proposed. One of them is to use a repair sleeve which confines the damaged area from the outside (McReynolds 1999). This method is suitable for emergency repair but it requires heavy lifting equipment and it is applicable only up to four feet diameter pipe in maximum. Another method is post- tension circumferential tendon system (Zarghamee et al. 1998). This method requires the removal of soil cover as well as the removal of PS wire. It may cause the cost and the environmental issues. The most popular repairing method currently used is an inner installation of steel cylinder (Fortner 1999). However, this method can be very costly in manufac- turing of inner steel and raises technical difficulties in insert- ing the steel. To overcome the difficulties in previous PCCP rehabilitation methods, a new approach using fiber reinforced polymer (FRP) has been applied. The FRP rehabilitation method relies on manual installation of FRP sheets, and thus is currently suitable only for sectional repairs to keep the line in service and to prevent failure once an imminent failure threat is detected. However, because detection methods can be unreliable and the labor cost is high, there is a need to auto- mate FRP technology to enable it to advance from high-cost sectional repairs (Lee 2011).
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Flexural Cracking Behavior Of Steel Fiber Reinforced Concrete Beams

Flexural Cracking Behavior Of Steel Fiber Reinforced Concrete Beams

Flexural cracking occurs in concrete beams when the developed tensile stress exceeds the tensile capacity of the concrete. Steel fiber is added to concrete due to its ability to restrict the growth of cracks and thus changing the brittle mode of composite to a strong matrix with superior crack resistance, improved ductility and distinctive post-cracking behavior prior to breakdown [1],[2]. Fiber reinforced concrete (FRC) is defined as ―concrete made with hydraulic cement, containing fine or fine and coarse aggregate and discontinuous discrete fibers that may also contain pozzolans and additives‖ [3]. The influence of the steel fibers on concrete properties has been considered by many researchers [4],[5],[6],[7],[8],[9],[10],[11],[12],[13],[14],[15]. Marar et al., [4] reported that the addition of steel fibers to improves resistance to impact and toughness characteristics of high strength concrete. Impact resistance of high strength concrete containing 2.0% fiber fraction increased by about 74 times compared to that of concrete without fiber. According to this study compression toughness was also increased due to the addition of steel fibers. Fatih et al.,[5] examined the addition of two different percentage of hooked steel fibres on toughness of concrete with two grades (20 and 30 MPa). Steel fibers with 60 mm in length and 0.75 mm in diameter were used in this research. The results showed an increase in the energy absorption of concrete grade 20 and 30 by 121% and 135%, respectively. Jodeiri et al.,[6] examined the effect of steel fibre on flexural capacity of reinforced concrete beam. The hooked- end steel fiber with length of 33 mm and diameter of 0.55 mm was used in this study. The results showed that the addition of steel fibres in concrete increases the first cracking load, ultimate load, stiffness and ductility of the concrete beams.
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Structural Behavior of Hair Fiber Reinforced Concrete Beams

Structural Behavior of Hair Fiber Reinforced Concrete Beams

increases in fibre amount. Throughout the analysis, only one of these small cracks developed earlier will continue to propagate into a large one. This led to a different location for the single main crack at failure in the beams. Moreover, the pull-out failure region is limited to the narrow zone that situated at the areas of tensile cracking as show for HF-RC beams. Furthermore, it is observed from the cracking pattern the beams without fiber showed high expanded compression zone and diagonal cracking since more fiber added the cracking pattern concentrated at mid-span and showed altering of mode of failure. However, the beams with insufficient amount of fiber did not exhibit cracking pattern more limited at mid-span of the beam that indicates the importance of the amount of fiber for altering the mode of failure. For instance the beams with full shear reinforcement when added fiber up to V f = 0.5 % the cracking pattern indicated mode of failure not altered since
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Laboratory Simulation of Corrosion Damage in Reinforced Concrete

Laboratory Simulation of Corrosion Damage in Reinforced Concrete

First, the circuits for constant voltage and constant current were set up. Then, the circuits for the constant voltage were closed and the voltages across the 1 X resistor were recor- ded. According to Ohm’s Law (V = IR), the current flowing in the circuit is effectively the same value as the voltage reading since the resistor has a resistance of 1 X. Next, the currents for the constant current circuits were adjusted such that at the start of the accelerated corrosion, all concrete columns were subjected to the same magnitude of corrosion current. The specimens were subsequently allowed to cor- rode and the current readings were taken on an hourly interval throughout the experiment until the desired per- centage steel loss (i.e. 8 %) had been achieved. By knowing the voltage readings across the specimens, it was also pos- sible to monitor the resistances of all the specimens throughout the experiment since the currents flowing in the various circuits were already known.
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Behavior of High Strength Reinforced Concrete Deep Beams with Openings

Behavior of High Strength Reinforced Concrete Deep Beams with Openings

In recent years, concrete deep beam interconnecting systems in building and precast construction have become increasingly popular worldwide. This is because there is a huge demand for structures to be built to high elevations due to the lack of land available, especially in major modern cities. The need for an accurate design methodology for deep beams with openings [1] [2] is becoming increasingly necessary with the subsequent growth in the use of deep beams in construction industry.

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1.
													Flexural behavior of reinforced concrete beams with nano-metakaolin

1. Flexural behavior of reinforced concrete beams with nano-metakaolin

Concrete is one of most broadly utilized construction materials in the planet, with two billion tons set worldwide every year. It is appealing in numerous applications because it offers considerable strength at a relatively low cost. Concrete can generally be produced of locally available constituents, can be cast into a wide variety of structural configurations, and requires minimal maintenance during service. Enormous reviews have been done to investigate the likelihood of using an extensive variety of materials as partial replacement material for cement in the preparation of concrete. The utilization of supplementary cementations material in the preparation of concrete may result in major saving of energy, cost and reduction in environmental pollution. It is additionally enhances workability, strength, durability and chemical resistance of concrete. There are number of supplementary cementations material are accessible, for example, fly ash, metakaοlin, silica fume, slag cement, rice husk, coconut shell etc.
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Numerical Modeling of the Thermal Behavior of Corrosion on Reinforced Concrete

Numerical Modeling of the Thermal Behavior of Corrosion on Reinforced Concrete

In this study, 3 rates of corrosions were chosen,  =25%,  =50% and  =75%. For each rate of corrosion, the size of rust is determined by equation 4 and will be injected into the numerical model. A flow of 1250 w/m ² is applied during 900s, for three durations during the heating, t=300s, t=600s and t=900s, and three durations during cooling t=1500s, t=3000s and t=4500s, the thermograms and the curves of evolution of temperature will be represented.

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Influence of shear reinforcement corrosion on the performance of under reinforced concrete beams

Influence of shear reinforcement corrosion on the performance of under reinforced concrete beams

Main reinforcement consisted of high yield (ribbed) bars with a nominal characteristic strength of 460 N/mm 2 . Shear reinforcement was 6mm di- ameter plain round mild steel bars of nominal cha- racteristic strength 250 N/mm 2 at a spacing of 65 mm. Cover was 50 mm to the shear reinforcement for the beams presented in this paper, as this also formed part of a larger investigation where the cover was varied. Two longitudinal hanger bars for the links were provided at the top of the beam cross sec- tion. These were 6 mm diameter plain round mild steel bars with a nominal characteristic yield strength of 250 N/mm 2 . The steel reinforcement was weighed before casting to enable the actual percentage corro- sion to be calculated at a later stage. In order to pre- vent corrosion in the main reinforcement, shrink wrap tubing was provided at the points of contact with the shear reinforcement to break the electrical circuit and hence prevent current flow to the main reinforcement during the accelerated corrosion process. Inspection of the main reinforcement at the end of the tests showed that this was an effective method of preventing accelerated corrosion of the main reinforcement.
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Analysis of concrete beams prestressed and post-tensioned with carbon fiber reinforced polymer (CFRP) bars.

Analysis of concrete beams prestressed and post-tensioned with carbon fiber reinforced polymer (CFRP) bars.

Grace and Abdel Sayed (1998) presented a paper on the effect of externally draped CFRP tendons on the strength o f bridges. Four prestressed concrete bridge models were constructed and tested under different loading conditions. Several factors were investigated as the deviator angle, deviator diameter, presence o f the cushioning material between the deviator and the tendon and the twisting angle taking place during post­ tensioning process. Based on the test results, it was concluded that the strength of the CFRP tendons is adversely affected by the magnitude of the draping angle. Reducing the draping angle, increasing the deviator diameter and cushioning the tendon at the deviator minimize the reduction in the tendon breaking force. Furthermore, it was found that externally draped tendons allow for larger deflection under ultimate load.
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