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1
Mohamed Sayed, Ahmed, Mohamed Mohamed Rashwan, and Mohamed Emad Helmy. "Experimental Behavior of Cracked Reinforced Concrete Columns Strengthened with Reinforced Concrete Jacketing." Materials 13, no. 12 (June 24, 2020): 2832. http://dx.doi.org/10.3390/ma13122832.
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Reinforced concrete (RC) columns often need to be strengthened or rehabilitated to allow them to carry the loads applied to them. In previous studies, RC columns have been strengthened by jacketing, without considering the occurrence of cracking. In this study, the behavior of RC columns strengthened externally by jacketing after cracking is analyzed. The accuracy of the existing models was verified by analyzing the performance of fifteen RC columns with different cross-sections to determine the effect of new variables, such as the column size, amount of steel reinforcement, and whether the column was cracked or not, on the effectiveness of strengthening. The analysis demonstrated that this strengthening technique could effectively improve both the ductility and strength of RC column cross-sections. The results indicate that the model suggested by the ACI-318 code can predict the ultimate load capacity of RC columns without strengthening, or strengthened by RC jacketing before or after cracking, with higher accuracy and material efficiency. The RC columns without strengthening met the safety limit of the ACI-318 model. However, for strengthened columns, a reduction coefficient must be used to enable the columns to meet the safety limit, with values of 94% and 76% for columns strengthened before and after cracking, respectively. Furthermore, strengthening after cracking affects the ultimate load capacity of the column, with 15.7%, 14.1%, and 13.5% lower loads for square, rectangular, and circular columns than those strengthened before cracking, respectively.
2
Anand, Praveen, and Ajay Kumar Sinha. "Effect of Reinforced Concrete Jacketing on Axial Load Capacity of Reinforced Concrete Column." Civil Engineering Journal 6, no. 7 (July 1, 2020): 1266–72. http://dx.doi.org/10.28991/cej-2020-03091546.
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Whenever a member of a structure becomes structurally deficient, it becomes vulnerable to the existing load and for the additional loads that it may be subjected to in the coming future. Since columns are the most important structural element, the structural retrofit of columns, relative to other structural elements is of prime importance. This study intends to investigate the performance and behaviour of an RC column jacketed with Reinforced Concrete columns under axial loads. The objective of this paper is to find out the efficiency of RC jacket in enhancing the strength of an existing RC column. A mathematical design based upon Indian Standards codes has been designed to identify the behaviour of jacketed RC columns. This has been followed by a finite element based numerical simulation using the same material properties as used in the process of designing. The simulation has been done in ABAQUS software with appropriate contact modelling. The analytical model considers that there is no bond slippage between the existing and new concrete surface i.e. the bond between the existing and new concrete is assumed to be perfect. This perfect bond between the surfaces has been modelled by using appropriate constraints in ABAQUS software. The finite element models show fair agreement with the designed values in terms of ultimate capacity and failure mode. The load bearing capacity enhancement of the RC jacketed column has been found to increase substantially. The enhancement capacity results obtained from the finite element software differs about 16-25% from the design values.
3
Park, Jong Wook, Sang A. Cha, Ji Eun Kang, Mohamad Mansour, and Jung Yoon Lee. "Axial Strain of Reinforced Concrete Columns." Advanced Materials Research 163-167 (December 2010): 1858–61. http://dx.doi.org/10.4028/www.scientific.net/amr.163-167.1858.
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The reinforced concrete members are designed to fail in flexural member to behave ductilely. Also the failure doesn’t impose on columns but beams. But according to the plastic collapse mechanism, the plastic hinge potentially developed at the bottom of the RC column near the base of the structure after flexural yielding. These columns are generally dominated by shear which led to sudden failure in post yielding region because of its relatively short span-to-depth ratio, so special care is needed. The deformability of column with short span-to-depth ratio is small compared with larger span-to-depth ratio column under reversed cyclic loading. Therefore the design of these kinds of RC columns necessitates the prediction of both the shear strength after flexural yielding and corresponding ductility of such members. Ten RC columns with varying axial force ratio and shear reinforcement ratio were tested under monotonic and reversed cyclic loading. The most affectable factor to column behavior was the axial force. The result indicates that concrete contribution to shear resistance in the plastic hinge region and axial strain were decreased as axial force.
4
Landović, Aleksandar, and Miroslav Bešević. "Experimental Research on Reinforced Concrete Columns Strengthened with Steel Jacket and Concrete Infill." Applied Sciences 11, no. 9 (April 29, 2021): 4043. http://dx.doi.org/10.3390/app11094043.
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Experimental research on axially compressed columns made from reinforced concrete (RC) and RC columns strengthened with a steel jacket and additional fill concrete is presented in this paper. A premade squared cross-section RC column was placed inside a steel tube, and then the space between the column and the tube was filled with additional concrete. A total of fourteen stub axially compressed columns, including nine strengthened specimens and five plain reinforced concrete specimens, were experimentally tested. The main parameter that was varied in the experiment was the compressive strength of the filler concrete. Three different concrete compression strength classes were used. Test results showed that all three cross-section parts (the core column, the fill, and the steel jacket) worked together in the force-carrying process through all load levels, even if only the basic RC column was loaded. The strengthened columns exhibited pronounced ductile behavior compared to the plain RC columns. The influence of the test parameters on the axial compressive strength was investigated. In addition, the specimen failure modes, strain development, and load vs. deformation relations were registered. The applicability of three different design codes to predict the axial bearing capacity of the strengthened columns was also investigated.
5
Zhu, Lei, Qing Feng Xu, Xiang Min Li, and Chun Ming Zhu. "Experimental Studies of Reinforced Concrete Column Capacity Affected by Core Drilling." Advanced Materials Research 133-134 (October 2010): 1195–200. http://dx.doi.org/10.4028/www.scientific.net/amr.133-134.1195.
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The paper presents the experimental studies of reinforced concrete column (RC column) capacity affected by core drilling. By testing three groups (9 total) of full scale concrete short columns, the experiment demonstrates that the axial compression capacity of RC columns after core drilling is reduced from 5.63% to 22.14% while the ultimate displacement decreases from 1.88% to 26.14%. The behavior of columns is altered from the axial compression failure to a small-eccentricity compression failure. The paper summarizes experiment results, followed by an investigation of the dominant factors, such as column effective cross section, drilling location, drilled hole repairing and reinforcing steels discontinued by drilling, that have impact on RC column capacity. The rationale of capacity variations of RC columns due to core drilling is also investigated.
6
Deng, Mingke, and Yangxi Zhang. "Seismic Performance of High-Ductile Fiber-Reinforced Concrete Short Columns." Advances in Civil Engineering 2018 (2018): 1–11. http://dx.doi.org/10.1155/2018/3542496.
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This study mainly aims to investigate the effectiveness of high-ductile fiber-reinforced concrete (HDC) as a means to enhance the seismic performance of short columns. Six HDC short columns and one reinforced concrete (RC) short column were designed and tested under lateral cyclic loading. The influence of the material type (concrete or HDC), axial load, stirrup ratio, and shear span ratio on crack patterns, hysteresis behavior, shear strength, deformation capacity, energy dissipation, and stiffness degradation was presented and discussed, respectively. The test results show that the RC short column failed in brittle shear with poor energy dissipation, while using HDC to replace concrete can effectively improve the seismic behavior of the short columns. Compared with the RC short column, the shear strength of HDC specimens was improved by 12.6–30.2%, and the drift ratio and the energy dissipation increases were 56.9–88.5% and 237.7–336.7%, respectively, at the ultimate displacement. Additionally, the prediction model of the shear strength for RC columns based on GB50010-2010 (Chinese code) can be safely adopted to evaluate the shear strength of HDC short columns.
7
Zheng, Jian Lan, and Wei Fan. "Experimental Investigation of the RC Columns Strengthened with Outer Closed SCC under Cyclic Loadings." Advanced Materials Research 446-449 (January 2012): 728–32. http://dx.doi.org/10.4028/www.scientific.net/amr.446-449.728.
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Experiment research for aseismic performance of RC Column strengthened by self-compacting concrete under second force is completed. By comparing three comparison columns and three columns strengthened by self-compacting concrete in low-cycle reciprocating horizontal loads seismic performance test, the specimen described the typical features of breakage, and the hysteresis and ductility of the RC column reinforced or not by self-compacting concrete is analyzed, the reinforcement effect by the different initial force is compared. The results show that: reinforcement by increasing the cross-section of self-compacting concrete is an effective method to significantly improve the shear strength of reinforced concrete columns and specimen ductility. The presence of the initial force have impact on reinforcing effect of RC columns, the greater the initial force, the more obvious impact.
8
Li, Kai Wen, Zhi Yang Li, Xin Wan, and Fei Liu. "Non-Linear Numerical Simulation on Hysteretic Behavior of SRC Columns." Applied Mechanics and Materials 723 (January 2015): 382–86. http://dx.doi.org/10.4028/www.scientific.net/amm.723.382.
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In order to study the mechanics properties to of concrete columns with embedded steel, two groups contrasting analysis models referring to SRC column and RC column are established by using finite element software ABAQUS. Both Static and cycle force are conducted. Analytical results show that bearing capacity and deformation ability of steel embedded reinforced concrete columns (SRC) under static loading are obviously higher than those of the reinforced concrete column (RC). Under the cycle force, the hysteresis circles of the SRC columns are fuller than RC column. The capability of energy consumption of the SRC columns is almost 1.4 times more than the RC columns. Further axial pressure coefficient and stirrup ratio are considered as parameters to study hysteresis characteristics, energy dissipation and the influence of the skeleton curve of SRC columns. The analytical results demonstrate that the hysteresis characteristics and energy dissipationare different with the changes of axial pressure coefficient. Meanwhile, the stirrup ratio of SRC column has little effect on energy dissipation. The study results have some value on the design and application of the SRC columns.
9
Weng, Jian, Kang Hai Tan, and Chi King Lee. "Identifying Buckling Resistance of Reinforced Concrete Columns During Inelastic Deformation." International Journal of Structural Stability and Dynamics 20, no. 03 (January 23, 2020): 2050029. http://dx.doi.org/10.1142/s0219455420500297.
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A simple solution method to identify buckling resistance of reinforced concrete (RC) columns during inelastic deformation is presented. Unlike conventional buckling solution methods, this proposed method predicts inelastic buckling loads of RC columns by directly solving the equilibrium differential equation under buckling. The method considers specific deflection configuration, end restraint conditions and inelastic material properties of the deformed column. In order to evaluate the reliability and accuracy of the proposed method, the results obtained from the purposed method are compared with the test results of eccentrically loaded RC columns. In addition, by using the proposed solution procedure, a parametric study is conducted to investigate the effects of critical RC column design parameters on column buckling behavior and resistance, including slenderness ratio, concrete strength, as well as longitudinal reinforcement and stirrup ratios. The results of the parametric study show that the proposed method is rational and can be adopted to effectively identify buckling resistance of RC columns subjected to inelastic damage, especially when load redistributions have occurred in the structure during progressive collapse.
10
Qiu, Wen Liang, Meng Jiang, and Le Zhou. "Seismic Performance of Reinforced Concrete Pier with Inside Concrete Filled Steel Tube." Advanced Materials Research 163-167 (December 2010): 4194–98. http://dx.doi.org/10.4028/www.scientific.net/amr.163-167.4194.
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A reinforced concrete column with inside concrete filled steel tube (RC-CFT) has many advantages over reinforced concrete (RC) column, such as higher compression, shear and moment capacity, higher ductility. So this kind of composite column has been used as frame column in buildings. In this paper, the composite columns are used as piers of a continuous bridge to improve the seismic performance. Using nonlinear time-history analysis method and fiber element model, considering elasto-plastic nonlinearity, the nonlinear relationships between lateral load and horizontal displacement of RC-CFT pier and RC pier are calculated, and the seismic behaviors of continuous bridges with the two types of piers are analyzed. Based on the comparison of the results, it is found that the ductility of RC-CFT pier is much larger than RC pier. Under the same intensity earthquakes, the damage of RC-CFT pier is less than the RC pier, and RC-CFT pier is more safe and easy to be repaired after earthquake.
11
Abay, Abreha, and Temesgen Wondimu. "Numerical Investigation of Bundled RC Column under Impact Load." Advances in Civil Engineering 2021 (August 23, 2021): 1–18. http://dx.doi.org/10.1155/2021/5587576.
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Dynamic impact load has an extensive application area in civil engineering, including highway, military, and marine structures. Many researchers have studied the performance of reinforced concrete (RC) columns under impact load. However, very limited work has been conducted on the effect of bundle reinforced concrete (BRC) columns subjected to lateral impact load. In this study, to examine the behavior of RC columns under impact load, numerical simulations of one with normal reinforcement distribution and three different bundles of reinforced concrete column specimens have been conducted using an explicit finite element (FE) analysis. In addition to the bundle reinforcement distribution, the parameters considered in the study are impact scenarios, impact velocity, pure axial load, and impact locations. From the numerical analysis, it has been found that bundling of longitudinal reinforcement does not only improve the impact capacity but also stabilizes the fluctuating response of impacted reinforced concrete columns. Both peak impact force and maximum lateral displacements of impacted BRC columns increase with increasing initial impact velocity. The numerical results also show that pure axial load slightly improved the impact capacity of the BRC columns. Finally, while the global failure of the RC column governs the response of repeatedly impacted BRC columns, failure characteristics of the single impacted columns are associated with local concrete damage at the impact zone.
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Tariq, Shah Rukh, Liaqat Ali Qureshi, Babar Ali, and Muhammad Usman Rashid. "Structural Behavior of RC Columns Improved by Different Strengthening Techniques." Slovak Journal of Civil Engineering 28, no. 3 (September 1, 2020): 20–28. http://dx.doi.org/10.2478/sjce-2020-0020.
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AbstractDeficient or deteriorating reinforced-concrete columns in many existing structures have to be strengthened using economical, efficient, and fast methods. In the present study, different strengthening techniques to improve the load-carrying capacity of reinforced concrete (RC) columns have been compared. Five groups of fifteen square reinforced concrete columns (150 mm × 150 mm × 600 mm) and one group of three circular columns ( φ 170 mm) that have cross-sectional areas equivalent to those of the square columns were cast from normal-strength concrete. The test program was designed to examine the behavior of columns strengthened by carbon fiber-reinforced polymer (CFRP), steel jacketing, ferro cement, steel fibers, and silica fumes under cyclic axial compression. The efficiency of each strengthening method in increasing the column’s axial capacity, energy absorption, and ductility was studied using the experimental data. The test results showed that strengthening the columns could significantly enhance their load-carrying capacity and failure strains.
13
Ge, Xiao, Matthew S. Dietz, Nicholas A. Alexander, and Mohammad M. Kashani. "Nonlinear dynamic behaviour of severely corroded reinforced concrete columns: shaking table study." Bulletin of Earthquake Engineering 18, no. 4 (November 8, 2019): 1417–43. http://dx.doi.org/10.1007/s10518-019-00749-3.
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Abstract A set of benchmark, medium scale, shaking table tests on corroded reinforced concrete (RC) columns is conducted with the aim of investigating the effects of corrosion damage on the nonlinear dynamic behaviour of RC bridge piers. The experimental programme consists of an uncorroded control specimen and two corroded RC column specimens, with identical structural details. An accelerated corrosion procedure is used to corrode the RC columns. The uncorroded and corroded specimens are subjected to far-field long duration ground motion excitations. The two corroded columns had 51% and 65% average mass loss ratios. The testing sequence includes slight, extensive, and complete damage levels, followed by an aftershock to examine the cascade effect on the nonlinear dynamic response of the proposed RC columns. The experimental results show that corrosion changes the failure mode of the RC columns, and has a significant negative impact on the residual strength (about 50% mass loss results in about 80% strength reduction) and drift capacity of RC columns.
14
Li, Yeou-Fong, Yan-Jie Lin, Cheng-Wei Chen, and Chih-Tsung Lin. "Theoretical and experimental studies on repaired and rehabilitated reinforced concrete frames." Canadian Journal of Civil Engineering 34, no. 8 (August 1, 2007): 923–33. http://dx.doi.org/10.1139/l07-012.
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In this paper, an effective repair and rehabilitation working method is proposed for moderately damaged reinforced concrete (RC) building structures after major earthquakes. Three RC frames with nil, half-height, and full-height brick walls are designed and tested at the National Center for Research on Earthquake Engineering (NCREE), Taiwan. After the columns of these nonductile RC frames are damaged, steel wire cables with nonshrinkage mortar are used to repair the damaged columns, and carbon fiber reinforced polymers (CFRP) are used to rehabilitate the damaged columns. A stress–strain relationship of the confined concrete is used in the theoretical sectional analysis. The columns are confined by steel wires and CFRP, and the "equivalent column model" is proposed in this paper and used to analyze the brick walls inside the RC frames. The analytical results can reasonably predict the lateral force–displacement relationships of these RC frames. Key words: nonductile frame, carbon fiber reinforced polymers, steel wire cable, repair, rehabilitation.
15
Ming, Liu, Yin Shi-Ping, and Cong Xi. "Seismic behavior of textile-reinforced concrete–strengthened RC columns under different axial compression ratios." Journal of Engineered Fibers and Fabrics 14 (January 2019): 155892501986570. http://dx.doi.org/10.1177/1558925019865705.
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To study the effect of various axial compression ratios on the seismic behavior of reinforced concrete (RC) columns strengthened with textile-reinforced concrete, in this study, an RC column model is established using the finite element analysis software, ABAQUS. This model’s seismic performance under earthquakes is investigated, and the numerical analysis results of the two test pieces are compared with the test results to verify the correctness of the model. The results show that the initial stage of RC loading is under the three-way restraint of the axial force and textile-reinforced concrete material. The yield load and peak load of the textile-reinforced concrete–strengthened RC column increase with the increase in the axial compression ratio. However, the increase in the axial pressure during the loading process accelerates the crack development. The displacement ductility coefficient and the energy dissipation capacity of the specimen are reduced as the axial compression ratio increases. The numerical calculation results of the textile-reinforced concrete–strengthened RC column are in good agreement with the experimental results, indicating that the numerical model based on ABAQUS is reasonable.
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Wan, Hai Tao, and Peng Li. "Test Research on Seismic Performance of Column." Applied Mechanics and Materials 166-169 (May 2012): 1058–61. http://dx.doi.org/10.4028/www.scientific.net/amm.166-169.1058.
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Reinforced concrete (RC) column component is a very important lateral force-resisting member which is widely used in China. Its seismic behavior has a great impact on the seismic performance of the overall structure. Damage of some reinforced concrete frame structures under the earthquake is caused by the damage of columns, So RC columns are an essential seismic members. The paper introduces the design of RC column specimen, mechanical properties of materials, production of RC column specimen, test method, loading device, loading system, the contents of measurement and data acquisition in detail. From the above analysis, it is obvious that the test is the most effective means of studying the seismic performance of column.
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Megalooikonomou, Konstantinos G. "PHAETHON: Software for Analysis of Shear-Critical Reinforced Concrete Columns." Modern Applied Science 12, no. 3 (February 7, 2018): 1. http://dx.doi.org/10.5539/mas.v12n3p1.
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Earthquake collapse of substandard reinforced concrete (RC) buildings, designed and constructed before the development of modern seismic design Codes, has triggered intense efforts by the scientific community for accurate assessment of this building stock. Most of the proposed procedures for the prediction of building strength and deformation indices were validated by assembling databases of RC column specimens tested under axial load and reversed cyclic lateral drift histories. Usually a column structural behavior is assessed by considering all involving mechanisms of behavior, namely flexure with or without the presence of axial load, shear and anchorage. In the present paper a force-based fiber beam/column element was developed accounting for shear and tension stiffening effects in order to provide an analytical test-bed for simulation of experimental cases such as the lightly reinforced columns forced to collapse. Their peculiar characteristics are the outcome of the shear – flexure interaction mechanism modeled here based on the Modified Compression Field Theory (MCFT) and the significant contribution of the tensile reinforcement pullout from its anchorage to the total column’s lateral drift. These features are embedded in this first-proposed stand-alone Windows program named “Phaethon” -with user’s interface written in C++ programming language code- aiming to facilitate engineers in executing analyses both for rectangular and circular substandard RC columns.
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Kim, Hyeong-Gook, Chan-Yu Jeong, Dong-Hwan Kim, and Kil-Hee Kim. "Confinement Effect of Reinforced Concrete Columns with Rectangular and Octagon-Shaped Spirals." Sustainability 12, no. 19 (September 26, 2020): 7981. http://dx.doi.org/10.3390/su12197981.
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Conventional spiral-type transverse reinforcement is effective at increasing the ductility and the maximum strength of reinforced concrete (RC) columns because it confines the inner concrete and the longitudinal reinforcement. However, when arranging crossties in a RC column with spirals, problems such as mutual interference with longitudinal reinforcement, overcrowding of reinforcement, and deterioration of constructability occur. Furthermore, the loosening of 90 and 130-degree standard hooks due to the lateral expansion of concrete causes buckling of the longitudinal reinforcement. This paper describes the ability of a newly developed spiral-type transverse reinforcement with various yield strengths to confine RC columns subjected to cyclic lateral load and constant axial load. The ductility capacity, energy dissipation, and effective stiffness of RC columns confined by the developed spiral-type transverse reinforcement were compared with those of RC columns confined by typical rectangular reinforcement. The experimental results showed that RC column specimens with the developed spiral-type transverse reinforcement have better performances in terms of ductility capacity and energy dissipation, even though the amount of reinforcement used for the specimens decreased by about 27% compared with the specimen with typical rectangular reinforcement.
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Hyun, Jung-Hwan, Jin-Wook Bang, Bang-Yeon Lee, and Yun-Yong Kim. "Effects of the Replacement Length of Concrete with ECC on the Cyclic Behavior of Reinforced Concrete Columns." Materials 14, no. 13 (June 25, 2021): 3542. http://dx.doi.org/10.3390/ma14133542.
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This paper presents an experimental investigation on the effects of the replacement length of concrete with engineered cementitious composites (ECC) on the cyclic behavior of a reinforced concrete (RC) column. A conventional RC column specimen and two RC composite columns designed with ECC were fabricated. To investigate the cyclic behavior of each specimen, a series of cyclic loading tests was performed under a reversed cyclic loading condition with a constant axial load. Test results showed that ECC columns exhibited higher cyclic behavior in terms of load carrying capacity, ductility, and energy dissipation capacity compared to the RC column. It was also found that when applying ECC to the column specimen with a length of 3.6d or more, the energy dissipation capacity was greatly increased.
20
Akhlaghi, Ebrahim. "Numerical Simulation of Air Shock Wave Propagation Effects in Reinforced Concrete Columns." Journal of Modeling and Optimization 12, no. 1 (June 15, 2020): 12–22. http://dx.doi.org/10.32732/jmo.2020.12.1.12.
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Reinforced concrete has been shown to be a desirable material of choice in blast resistant structures due to its availability, relatively low cost, and its inherent ability to absorb energy produced by explosions. Most research work investigating the behaviour of reinforced concrete columns to blast loading have concentrated on their response to planar loading from far-field explosions. Limited amount of work is available on the effects of near-field explosion on the behaviour of reinforced concrete columns. This study is aimed to investigate effects of explosive loads on RC column by using ALE method. Commercial finite element package, LS-DYNA is used to simulate the behavior of blast wave on RC columns. Numerical simulation is validated against experimental work done in literature. The experience gained from this research provides valuable information for the development of the finite element modeling of real blast load effects on RC columns.
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Navdar, M. Burhan, and Naci Caglar. "Numerical Investigation of Behavior of RC Columns Strengtheneg with RC Jacket." Academic Perspective Procedia 2, no. 2 (October 27, 2019): 257–64. http://dx.doi.org/10.33793/acperpro.02.02.39.
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Strengthening of structural elements which are insufficient in terms of earthquake performance is very important for the safety of existing structures. Nowadays, one of the most commonly used methods is strengthening such members with RC jacketing. Several experimental studies have been conducted in the literature to investigate behavior of structural elements reinforced with RC jacketing. Moreover, numerical studies are frequently preferred due to the high cost of experimental studies and the limited availability of laboratory facilities. In this study, a finite element model has been created with OpenSees program in order to investigate the behavior of strengthened RC columns with jacketing. Later, the accuracy of the model has been verified successful by the experimental results selected from the literature. By using that verified model, the effects of concrete strength and amount of spacing of transverse reinforcement used on the jacketing part on reinforced column behavior were investigated. As a result of the study, it is deduced that the change in the concrete strength and amount of transverse reinforcement results in a significant change in ductility, load capacity and rigidity of the reinforced concrete columns.
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Eid, Rami, Avi Cohen, Reuven Guma, Eliav Ifrach, Netanel Levi, and Avidor Zvi. "High-Strength Concrete Circular Columns with TRC-TSR Dual Internal Confinement." Buildings 9, no. 10 (October 14, 2019): 218. http://dx.doi.org/10.3390/buildings9100218.
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The standard requirements for transverse steel reinforcement (TSR) confinement in reinforced-concrete (RC) columns are mainly to provide the following: ductile behavior, minimum axial load capacity of the column’s core, and prevention of longitudinal bars buckling. It is well-known that the passive confinement due the TSR action is less effective in high-strength concrete (HSC) compared to normal-strength concrete (NSC). Therefore, the TSR amounts required by the standards for HSC columns are high, and in some cases, especially in the lower stories columns of high-rise buildings, are impractical. This paper presents a new construction method using textile-reinforced concrete (TRC) as internal confinement together with reduced TSR amounts. Moreover, comparison of the proposed method with RC columns casted in fiber-reinforced polymer (FRP) stay-in-place forms as additional external confinement, is presented. Eleven large-scale column specimens were tested under axial compression. The results give an insight on the application feasibility of the proposed construction method. It is shown that the TRC-TSR dual internal confinement action can be an option to reduce the standard required TSR amounts while maintaining similar levels of ductile behavior.
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Zhang, Qin, Zong-yan Wei, Jin-xin Gong, Ping Yu, and Yan-qing Zhang. "Equivalent Viscous Damping Ratio Model for Flexure Critical Reinforced Concrete Columns." Advances in Civil Engineering 2018 (July 15, 2018): 1–15. http://dx.doi.org/10.1155/2018/5897620.
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In order to determine the energy dissipation capacity of flexure critical reinforced concrete (RC) columns reasonably, an expression for describing the hysteretic behavior including loading and unloading characteristics of flexure critical RC columns is presented, and then, a new equivalent viscous damping (EVD) ratio model including its simplified format, which is interpreted as a function of a displacement ductility factor and a ratio of secant stiffness to yield stiffness of columns, is developed based on the proposed hysteretic loop expression and experimental data from the PEER column database. To illustrate the application of the proposed equivalent damping ratio model, a case study of pushover analysis on a flexure critical RC bridge with a single-column pier is provided. The analytical results are also compared with the results obtained by other models, which indicate that the proposed model is more general and rational in predicting energy dissipation capacity of flexure critical RC structures subjected to earthquake excitations.
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Liu, Cheng Qing, Wei Xing Shi, Shi Chun Zhao, and Yi Pan. "Study on Destructive Modes of RC Frame Columns in Wenchuan Earthquake." Advanced Materials Research 250-253 (May 2011): 1597–601. http://dx.doi.org/10.4028/www.scientific.net/amr.250-253.1597.
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Typical earthquake damages of Reinforced concrete columns in the Wenchuan earthquake are introduced, and the damage characteristics of concrete columns are described, then several typical destructive modes of Reinforced concrete columns are summarized. Further, various reasons of destructive modes are analyzed. Final, some practical advices are proposed to reduce the damages of reinforced concrete columns.
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Rodsin, Kittipoom. "Ductility Enhancement of High Strength RC Columns Using Steel Fiber Reinforced Concrete (SFRC)." Advanced Materials Research 931-932 (May 2014): 463–67. http://dx.doi.org/10.4028/www.scientific.net/amr.931-932.463.
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The principal aim of this research is to improve the seismic performance of high strength concrete (HSC) reinforced columns using fiber reinforced concrete (FRC) by mixing steel fiber into the concrete. Two reinforced concrete columns 200mm x 300mm in cross-section with a height of 1250 mm were tested under cyclic lateral loading. The first specimen was casted using high strength concrete of 100 MPa and the second specimens were also casted using similar concrete strength but the steel fiber of 0.5% by volume was added to the concrete in the plastic hinge region. Both columns were subjected to lateral cyclic load until the failure occurs. The test results showed that the use of FRC in the plastic hinge region could significantly improve column displacement ductility. The maximum drift at column failure at 4.5% for non-ductile column could increase to 8% in FRC column. It is evident that the cracks in FRC column are much smaller properly spread in the plastic hinge region and hence the plastic hinge could be able to rotate without lateral strength being compromised. In FRC column, concrete spalling was observed in a very high drift (7%) and bar buckling occurred at around 8% drift whilst in HSC column concrete spalling and bar buckling occurred at only 3.5% and 4% drift respectively. It was evident that the use of steel fiber in HSC columns could significantly improve seismic performance of the column.
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Wang, Jing Feng, Jun Wang, and Ben Hua Wu. "Seismic Behaviour of Reinforced Gangue Concrete Columns." Advanced Materials Research 446-449 (January 2012): 683–87. http://dx.doi.org/10.4028/www.scientific.net/amr.446-449.683.
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This paper presents an experimental study to know the seismic behaviour of the reinforced gangue concrete (RGC) columns. Four specimens of the RGC columns under cycle loadings were tested. The failure models, hysteretic performance, degradation rules of strength and stiffness, ductility and energy dissipation capacity are described and evaluated. It was concluded that the strength and stiffness of the RGC columns were improved with the increasing of steel ratio, column cross-section dimension and concrete strength. The tested RGC columns exhibit excellent seismic performance. The RGC columns have excellent ductility and can satisfy the request of the structural seismic design, thus they can be effectively used in RC structures.
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Liu, Li Xian, Long Lv, and Yan Feng Zhao. "Nonlinear Structural Analysis of Fire-Exposed Reinforced Concrete Column." Advanced Materials Research 1095 (March 2015): 267–75. http://dx.doi.org/10.4028/www.scientific.net/amr.1095.267.
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A nonlinear structural analysis is presented for reinforced concrete (RC) columns exposed to fire. The analysis includes two steps: the first step is the calculation of the temperature distribution in concrete members, and the second the determination of the mechanical response due to elevated temperature and applied loading. In the thermal analysis, the effect of moisture is taken into account. The use of the computer program for evaluating the response of a RC column from the initial preloading stage to collapse, due to fire, is illustrated. The validity of the numerical model used in the program is verified by comparing the predictions from the computer program with measured results from full-scale fire resistance tests. The computer program can be used to predict the fire resistance of RC columns for any values of the significant parameters, such as load level, section dimensions, column length, concrete strength, concrete cover, aggregate type and reinforcement ratio.
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Mhuder, Wathiq Jassim, and Samir M. Chassib. "Experimental Study of Strengthening of RC Columns with Steel Fiber Concrete." Materials Science Forum 1002 (July 2020): 551–64. http://dx.doi.org/10.4028/www.scientific.net/msf.1002.551.
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This study introduces an experimental program to investigate the performance of concrete wrapping jackets reinforced by steel fibers used for retrofitting of the square and circular RC columns under axial loads. Ten columns divided into two groups; the first group included seven square columns while the second group involved three circular columns. The experimental study included testing the columns with varied parameters such as cross-section shape, type and aspect ratio of steel fibres, jacket thickness, and using several techniques for retrofitting the column such as strengthening by plain and reinforced concrete jackets. The selected parameters affected the compressive behavior of confined columns high strength concrete jackets. The obtained results revealed that all strengthened columns with square cross-section appeared maximum strength greater than a circular one. Using several types of concrete jacketing promotes the load-capacity of the column with a clear improvement in the ductility. Increasing thickness appeared increasing in the load-carrying capacity in comparison with the reference column. Using the straight fibres showed better enhancement in the load capacity than the hooked ones. The main result was the failure mode was different from unstrengthen columns which showed more crushing in the concrete core with an increase in thickness.
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Xie, Yong Ping, Lei Jia, and Gang Sun. "Review on Seismic Behavior of RC Columns." Applied Mechanics and Materials 353-356 (August 2013): 2092–96. http://dx.doi.org/10.4028/www.scientific.net/amm.353-356.2092.
Full textAbstract:
Column is the key member of the seismic structures, after the earthquake destroyed, not only cause column serious economic damage, and will cause a large number of casualties. For studying the seismic behavior and size effect of full-scale reinforced concrete columns. A comprehensive summary of the experimental results is undertaken to evaluate the seismic behavior of RC concrete columns, including test equipment and load method and mode of failure and Seismic behavior. It is concluded that the ductility and shear capacity of RC mainly depends on shear span ratio, axial load ratio and stirrup ratio. But the seismic behavior of large scale RC columns has no systematic studied.
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H. Hameed, Mohammed, Ali Hussein Ali Al-Ahmed, and Zena K. Abbas. "Experimental Investigation of Reinforced Concrete Columns with Steel Embedded Tubes." Key Engineering Materials 878 (March 2021): 134–43. http://dx.doi.org/10.4028/www.scientific.net/kem.878.134.
Full textAbstract:
This study aimed to investigate the influence of longitudinal steel embedded tubes located at the center of the column cross-section on the behavior of reinforced concrete (RC) columns. The experimental program consisted of 8 testing pin-ended square sectional columns of 150×150 mm, having a total height of 1400 mm, subjected to eccentric load. The considered variables were the steel square tube sizes of 25, 51 and 68 mm side dimensions and the load eccentricity (50 and 150) mm. RC columns were concealed steel tubes with hollow ratios of 3%, 12% and 20% depending on tube sizes used. The experimental results indicated an improvement in the overall behavior of eccentric columns when steel embedded tubes are used. The maximum gain in strength was about 59% for the hollow ratio of 20% with e/h=1. The test results show that the inserted steel pipe improves strength, ductility and enables these columns to absorb more energy than a similar solid column.
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Li, Qiang, Xianyu Jin, Dan Wu, and Hailong Ye. "Acoustic Emission Analysis of Corroded Reinforced Concrete Columns under Compressive Loading." Sensors 20, no. 8 (April 23, 2020): 2412. http://dx.doi.org/10.3390/s20082412.
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In this work, the failure process of non-corroded and corroded reinforced concrete (RC) columns under eccentric compressive loading is studied using the acoustic emission (AE) technique. The results show that reinforcement corrosion considerably affects the mechanical failure process of RC columns. The corrosion of reinforcement in RC columns leads to highly active AE signals at the initial stage of loading, in comparison to the non-corroded counterparts. Also, a continuous AE hit pattern with a higher number of cumulative hits is observed for corroded RC columns. The spatial distribution and evolution of AE events indicate that the reinforcement corrosion noticeably accelerates the initiation and propagation of cracking in the RC columns during compressive loading. The AE characteristics of corroded RC columns are in agreement with the macroscopic failure behaviors observed during the damage and failure process. A damage evolution model of corroded RC columns based on the AE parameters is proposed.
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Zhou, Ying Wu, Ling Yi Wu, Li Li Sui, and Feng Xing. "Experimental Studies on the Mechanical Performances of Corroded Reinforced Concrete Columns Retrofitted with FRP." Applied Mechanics and Materials 405-408 (September 2013): 726–30. http://dx.doi.org/10.4028/www.scientific.net/amm.405-408.726.
Full textAbstract:
Due to the superiority of high corrosion resistance of FRP materials, more and more attentions have been attracted to the retrofitting of corroded reinforced concrete (RC) columns with FRP. This paper thus presents an experimental study on mechanical performances of corroded RC columns strengthened with FRP, focusing on the effects of different corrosion rates of the reinforcements and the retrofitting scheme. The effectiveness of externally bonded FRP to the corroded RC column to increase its load capacity and ductility is tested; the mechanical performances of the strengthened columns are theoretically investigated. The results indicate that the effectiveness of retrofitting the existing corroded RC columns with FRP jackets is much more significant than that of retrofitting the newly built columns with FRP jackets and externally wrapped with FRP jackets is much more effective to improving the structural performances of heavily corroded columns.
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Foroughi, Saeid, and Süleyman Bahadır Yüksel. "Investigation of moment-curvature and effective section stiffness of reinforced concrete columns." Challenge Journal of Structural Mechanics 7, no. 3 (September 15, 2021): 135. http://dx.doi.org/10.20528/cjsmec.2021.03.003.
Full textAbstract:
In determining the seismic performance of reinforced concrete (RC) structures in national and international seismic code, it is desired to use effective section stiffness of the cracked section in RC structural elements during the design phase. Although the effective stiffness of the cracked section is not constant, it depends on parameters such as the dimension of the cross-section, concrete strength and axial force acting on the section. In this study, RC column models with different axial load levels, concrete strength, longitudinal and transverse reinforcement ratios were designed to investigate effective stiffness. Analytically investigated parameters were calculated from TBEC (2018), ACI318 (2014), ASCE/SEI41 (2017), Eurocode 2 (2004) and Eurocode8 (2004, 2005) regulations and moment-curvature relationships. From the numerical analysis results, it is obtained that the axial load level, concrete strength, longitudinal and transverse reinforcement ratios have an influence on the effective stiffness factor of RC column sections. The calculated effective stiffness for RC columns increases with increasing transverse reinforcement ratio, longitudinal reinforcement ratio and concrete strength. Due to the increase of axial force, effective stiffness values of concrete have increased.
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Zhang, Guo Jun, Yong Bin Jia, and Xi Lin Lu. "Cracking Simulative Analysis of Reinforced Concrete Columns with ANSYS Software." Applied Mechanics and Materials 578-579 (July 2014): 946–49. http://dx.doi.org/10.4028/www.scientific.net/amm.578-579.946.
Full textAbstract:
The principle and processof finite element model of ANSYS software for RC frame column was introduced firstly,and then the cracking and development rules of RC columns under monotonic load were analyzed with ANSYSsoftware. The results show that: with the stirrup ratios increasing, the short columnwith rectangle hoop, rectangle cross brace hoop and tic tac toe stirrups appearsuccessively few inclined cracks and more vertical cracks; with the axialcompression ratio increasing, more length of horizontal cracks extend to naturalaxis, more vertical cracks appear and appeared cracks are higher along thecolumn height direction for middle length HSC frame columns; the length of OSCframe columns is not so long than that of HSC frame columns, and the crack distributionis dense and crack forms mesh, which show better ductility.
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Ding, Hong Yan, Xi Chen, Pu Yang Zhang, and Chao He. "Economic Evaluation of a New Type of Reinforced Concrete Structure with Fabricated Concrete Tubular Columns." Advanced Materials Research 671-674 (March 2013): 2999–3002. http://dx.doi.org/10.4028/www.scientific.net/amr.671-674.2999.
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A new type of reinforced concrete (RC) structure termed concrete filled fabricated concrete tubular (CFFCT) was economically evaluated. Construction schedule time and construction cost of CFFCT and RC columns were analyzed both in case studies of building structure and bridge structure. A comparative analysis was done on two types of columns by studying on single column and present value of total construction cost. The results show that use of CFFCT shortens the construction schedule time and lowers the total construction cost. The investigation of the multistory building shows that using CFFCT results in an average of 2.31% savings on total project cost, an average of 28.67% savings on total column costs, 25.12% savings on total project time period, and 45.22% savings on columns construction time period. And the investigation of the bridge shows that using CFFCT results in an average of 3.27% savings on total project cost, an average of 46.87% savings on total column costs, 15.68% savings on total project time period, and 29.90% savings on columns construction time period.
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Bai, Li Li, and Tao Song. "Failure Analysis of Reinforced Concrete Columns after High Temperature." Applied Mechanics and Materials 157-158 (February 2012): 1578–81. http://dx.doi.org/10.4028/www.scientific.net/amm.157-158.1578.
Full textAbstract:
Mechanics models of RC(reinforced concrete) columns is established, after the limit state equation was formed, the failure modes of RC eccentric compression columns after high temperature is analyzed under considering various failure paths. Analysis results indicates that failure analysis is not safe under considering single failure mode, so comprehensive considering failure modes is more matching the true situation than only considering single factor when evaluate reliability of RC eccentric compression columns post-fire
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Wang, Gaoxiong, Yanhong Bao, Li Yang, and Yang Yu. "Analysis of Fire Resistance of Square-Cased Square Steel Tube Reinforced Concrete (ST-RC) Columns." Materials 14, no. 19 (September 24, 2021): 5541. http://dx.doi.org/10.3390/ma14195541.
Full textAbstract:
Based on the finite element (FE) analysis software Abaqus, an FE model of square-cased square steel tube reinforced concrete (ST-RC) columns under the hybridized action of high-temperature and load is established. The accuracy of the FE model is verified using experimental data from existing studies. This model is used to analyze the temperature change, internal force distribution, and failure characteristics of the square-cased square ST-RC columns under the action of fire, as well as the factors affecting the fire resistance limit of the column. The results of FE analysis show that under the action of fire, the maximum internal temperature of the square-cased square ST-RC columns occurs in the corner of the section. Moreover, the stress and strain reach their maximum values at the concrete corner outside the tube. During the heating process, an internal force redistribution occurs in the square-cased square ST-RC column. At the same time, the proportion of the axial force and the bending moment of the reinforced concrete outside the pipe decreases gradually, while the proportion of the internal force of the core concrete-filled steel tube (CFST) increases gradually. In essence, it is a process of load transfer from the high-temperature to the low-temperature zone. In addition, the section size, load ratio, slenderness ratio, cross-sectional core area ratio, steel content, and external concrete strength are the main parameters affecting the fire resistance limit of the square-cased square ST-RC columns. Among them, the cross-sectional core area ratio, section size, steel ratio, and external concrete strength are positively correlated with the fire resistance limit of the composite column. On the contrary, with the increase in the load ratio and the slenderness ratio, the fire resistance limit of the square-cased square ST-RC columns decreases. On this basis, a simplified formula to calculate the fire resistance limit of square-cased square ST-RC columns is proposed. The research results can be used as a theoretical reference for the fire protection design of this kind of structure in practical engineering.
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Xiamuxi, Alifujiang, Akenjiang Tuohuti, and Akira Hasegawa. "A Discussion on Numerical Simulation of Axial Reinforcements in RC and RCFT Columns." Advanced Materials Research 859 (December 2013): 186–90. http://dx.doi.org/10.4028/www.scientific.net/amr.859.186.
Full textAbstract:
In numerical simulations of reinforced concrete (RC) columns with ADINA, when the REBAR element model is applied to simulate the reinforcement, the load-displacement curve of RC is similar to that of concrete, without reflecting the contribution of reinforcement. Therefore, employing another element model-BEAM element model for reinforcement, nonlinear analyses of RC columns are carried out and compared against the REBAR element model. The nonlinear analysis of reinforced concrete filled steel tubular (RCFT) columns, then, is performed with the BEAM element model. Meanwhile, the axial compression tests of concrete, RC and RCFT columns are also conducted to validate the nonlinear analysis. Comparing the results of nonlinear analysis against the results of experiment, it is concluded that the BEAM element model can simulate the reinforcement more reasonably than REBAR element model and can be applied to the nonlinear analysis of RCFT columns.
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Wang, Zhi Bin, and Li Ying Liu. "Finite Element Modelling of Concrete-Filled Steel Tube Reinforced Concrete Stub Columns under Axial Compression." Applied Mechanics and Materials 351-352 (August 2013): 138–42. http://dx.doi.org/10.4028/www.scientific.net/amm.351-352.138.
Full textAbstract:
Concrete-filled steel tube reinforced concrete (CFSTRC) columns are currently being studied as a popular method to improve the shear strength, the ductility and the seismic behaviour of reinforced concrete (RC) columns. Owing to the complexity of confinement provided by steel tubes and stirrups, the behaviour of CFSTRC column is difficult to be accurately simulated. Thus,so far there is not a finite element (FE) model for CFSTRC columns. For studying the performance of this composite column, a FE model was developed based on the existing test results and theories. The predicted results using this FE model agree with the test results, which means that this model can be applied to carry out the further mechanism analysis.
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Song, Kun, and Zhen Bao Li. "Seismic Behavior of RC Columns With Corner Focus Longitudinal Bars." Applied Mechanics and Materials 470 (December 2013): 876–79. http://dx.doi.org/10.4028/www.scientific.net/amm.470.876.
Full textAbstract:
Many frame structures were damaged for the column hinge mechanism in the Wenchuan earthquake because of the biaxial seismic action. Four reinforced concrete columns with corner focus longitudinal bars were tested to improve the seismic behavior of RC columns subjected to multiaxial loading. The hysteretic behavior, skeleton curves and feature points were discussed. The results indicate that the method can improve seismic behavior of RC columns
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Tu, Jianwei, Kui Gao, Lang He, and Xinping Li. "Experimental study on the axial compression performance of GFRP-reinforced concrete square columns." Advances in Structural Engineering 22, no. 7 (December 22, 2018): 1554–65. http://dx.doi.org/10.1177/1369433218817988.
Full textAbstract:
At present, extensive studies have been conducted relative to the topic of fiber-reinforced polymer(FRP)- reinforced concrete (RC) flexural members, and many design methods have also been introduced. There have, however, been few studies conducted on the topic of FRP-RC compression members. In light of this, eight glass-fiber-reinforced polymer (GFRP)-RC square columns (200×200×600 mm) were tested in order to investigate their axial compression performance. These columns were reinforced with GFRP longitudinal reinforcement and confined GFRP stirrup. These experiments investigated the effects of the longitudinal reinforcement ratio, stirrup configuration (spirals versus hoops) and spacing on the load-carrying capacity and failure modes of GFRP-RC rectangular columns. The test results indicate that the load-carrying capacity of longitudinal GFRP bars accounted for 3%-7% of the ultimate load-carrying capacity of the columns. The ultimate load-carrying capacity of RC columns confined with GFRP spirals increased by 0.8%-1.6% with higher ductility, compared to GFRP hoops. Reducing the stirrup spacing may prevent the buckling failure of the longitudinal bars and increase the ductility and load-carrying capacity of the GFRP-RC columns. It has been found that setting the GFRP compressive strength to 35% of the GFRP maximum tensile strength yields a reasonable estimate of ultimate load-carrying capacity of GFRP-RC columns.
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Hou, Dongxu, Jianyun Pan, Xinglang Fan, Zhimin Wu, and Prosper Marindiko. "Evaluation of Seismic Behaviors of Partially Deteriorated Reinforced Concrete Circular Columns Retrofitted with CFRP." Mathematical Problems in Engineering 2014 (2014): 1–14. http://dx.doi.org/10.1155/2014/683057.
Full textAbstract:
Deficiency of the concrete strength in some regions of reinforced concrete (RC) columns in practice may weaken the seismic behaviors of columns. Its effects on RC columns should be well understood. This paper aims to investigate the influences of deteriorated segment on the seismic behaviors of partially deteriorated RC columns and attempts to recover the seismic behaviors of partially deteriorated columns with Carbon Fiber Reinforced Polymer (CFRP) composites. A finite element analysis was carried out to simulate the seismic behaviors of CFRP-confined partially deteriorated RC columns. The numerical results were verified by the laboratory tests of six specimens. Based on the finite element results, the failure location of partially deteriorated columns in an earthquake was predicted, and the effectiveness of CFRP retrofitted on partially deteriorated columns was evaluated.
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Ngo, Dang Quang, Huy Cuong Nguyen, Dinh Loc Mai, and Van Hiep Vu. "Experimental and Numerical Evaluation of Concentrically Loaded RC Columns Strengthening by Textile Reinforced Concrete Jacketing." Civil Engineering Journal 6, no. 8 (August 1, 2020): 1428–42. http://dx.doi.org/10.28991/cej-2020-03091558.
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Nowadays, Textile Reinforced Concrete (TRC) has become a very popular strengthening technique for concrete structures. This paper presents an investigation on the applicability of TRC for strengthening reinforced concrete column. Both experimental and numerical studies are conducted to evaluate the confinement effects of various TRC strengthening schemes. The experimental study is performed on a series of six reinforced concrete square columns tested to failure. Two of them were un-strengthened as references, the other four were strengthened by one or two layers of Carbon Textile Reinforced Concrete (CTRC). The results indicated that the application of carbon TRC enhanced the ductility and ultimate strength of the specimens. Failure of all strengthened columns was together with tensile rupture of textile reinforcements at the corners of column. Finite element models of the CTRC strengthened columns based on ATENA software package were developed and verified with the experimental results. The analytical results show that in the specimen corner areas, textile reinforcements are subjected to a 3D complicated stress state and this may be the cause of their premature failure.
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Abid, Muhammad, Haytham F. Isleem, Muhammad Kamal Kamal Shah, and Shayan Zeb. "Analytical Review on Eccentric Axial Compression Behavior of Short and Slender Circular RC Columns Strengthened Using CFRP." Polymers 13, no. 16 (August 17, 2021): 2763. http://dx.doi.org/10.3390/polym13162763.
Full textAbstract:
Although reinforced concrete (RC) columns subjected to combined axial compression and flexural loads (i.e., eccentric load) are the most common structural members used in practice, research on FRP-confined circular RC columns subjected to eccentric axial compression has been very limited. More specifically, the available eccentric-loading models were mainly based on existing concentric stress–strain models of FRP-confined unreinforced concrete columns of small scale. The strength and ductility of FRP-strengthened slender circular RC columns predicted using these models showed significant errors. In light of such demand to date, this paper presents a stress–strain model for FRP-confined circular reinforced concrete (RC) columns under eccentric axial compression. The model is mainly based on observations of tests and results reported in the technical literature, in which 207 results of FRP-confined circular unreinforced and reinforced concrete columns were carefully studied and analyzed. A model for the axial-flexural interaction of FRP-confined concrete is also provided. Based on a full parametric analysis, a simple formula of the slenderness limit for FRP-strengthened RC columns is further provided. The proposed model considers the effects of key parameters such as longitudinal and hoop steel reinforcement, level of FRP hoop confinement, slenderness ratio, presence of longitudinal FRP wraps, and varying eccentricity ratio. The accuracy of the proposed model is finally validated through comparisons made between the predictions and the compiled test results.
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Nakada, Kozo, Kochi Masaaki, Yu Yun Dong, and Long Yu. "Axial Compression Capacity of Shear-Damaged Reinforced Concrete Columns and Lashing Belt Prestressing." Key Engineering Materials 711 (September 2016): 1012–18. http://dx.doi.org/10.4028/www.scientific.net/kem.711.1012.
Full textAbstract:
The compressive strength and ductility of concrete can be considerably improved by lateral confinement. In this study, an emergency seismic retrofit technique using lashing belt prestressing is used as to manually retrofit damaged reinforced concrete (RC) columns. The initial prestressing is an important aspect of this technique and is introduced by the ratchet buckle. Thus, this technique offers active and passive confinement as well as shear strengthening. Furthermore, diagonal cracks in the damaged RC columns can be closed by using the active confinement of lashing belts, and the lateral and vertical load-carrying capacity and ductility of the damaged RC columns are recovered. In this study, the recovered axial compression capacity of the retrofitted RC columns and repaired RC columns using epoxy resin was investigated. Finally, the hysteretic behavior of the shear-damaged RC columns after the proposed emergency retrofit was investigated.
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Hong, H. P., and W. Zhou. "Assessment of time-dependent reliability of reinforced concrete columns with uncertain load eccentricity." Canadian Journal of Civil Engineering 27, no. 3 (June 1, 2000): 389–99. http://dx.doi.org/10.1139/l99-060.
Full textAbstract:
An approach for the time-dependent reliability analysis of reinforced concrete (RC) columns considering the correlation between the axial load and the bending moment or the uncertainty in the load eccentricity is presented. The approach recursively uses the efficient first-order reliability method for the time-dependent reliability analysis. The proposed approach is more efficient than the ones used in the literature for the reliability analysis of RC columns. The proposed approach is used to carry out sensitivity analyses of the reliability of short RC columns to the time-dependent live load effects and to the correlation between the axial load and the bending moment. Results of the analyses suggest that the reliability of RC columns can be sensitive to the correlation between the axial load and the bending moment due to live load. The differences between the reliability indices obtained by considering the live load modeled as a pulse process and as an extreme variate can be large.Key words: reliability, load, time-dependent, time-independent, uncertainty, correlation, concrete, reinforcement, column.
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Song, Jun-Hyeok, Eun-Taik Lee, and Hee-Chang Eun. "Shear Strength of Reinforced Concrete Columns Retrofitted by Glass Fiber Reinforced Polyurea." Civil Engineering Journal 6, no. 10 (October 1, 2020): 1852–63. http://dx.doi.org/10.28991/cej-2020-03091587.
Full textAbstract:
Aged structures and structures constructed based on outdated non-seismic design codes should be retrofitted to enhance their strength, ductility, and durability. This study evaluates the structural performance of reinforced concrete (RC) columns enhanced via polyurea or glass fiber reinforced polyurea (GFRPU) strengthening. Four RC column specimens, including a reference specimen (an unstrengthened column), were tested to evaluate the parameters of the strengthening materials and the strengthened area. The tests were carried out under a combined constant axial compressive load and quasi-static cyclic loading. The experimental results show that the composite strengthening provides lateral confinement to the columns and leads to enhanced ductility, shear-resistance capacity, and dissipated energy. The shear strength provided by the composites depends on the degree of lateral confinement achieved by the composite coating. The specimens finally failed through the development of diagonal tension cracks within the potential plastic hinge regions. The specimen treated with GFRPU strengthening showed greater strength and dissipated more energy than the specimen treated with polyurea strengthening. Furthermore, by modifying ATC-40, this study proposed an equation to estimate the shear capacity provided by the composites.
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Blikharskyy, Yaroslav, Roman Khmil, and Zinoviy Blikharskyy. "Research of RC columns strengthened by carbon FRP under loading." MATEC Web of Conferences 174 (2018): 04017. http://dx.doi.org/10.1051/matecconf/201817404017.
Full textAbstract:
The usage of carbon fiber-reinforced polymers (FRP) are described as modern methods of strengthening for reinforced concrete constructions. The advantage of these materials are the great corrosion resistance to environmental factors, high stiffness and strength and weight in comparison with other materials. The disadvantage of relatively high cost is offset by the cost reduction and labor when performing work on strengthening, by decreasing of performance time, by lack of needs to use the expensive equipment, installed and used without unloading the structures. This paper presents experimental results of 6 reinforce concrete columns strengthened by CFRP strips Sika Carbodur S512 with 50 mm width. The comparative analysis was carried out and strengthened effectiveness was determined for 2 unstrengthen control specimens, 2 specimens strengthened without initial load and 2 specimens strengthened at 1/2 of experimentally determined destructive efforts of the unstrengthen column.
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Kittipoom, Rodsin, Sappakittipakorn Manote, and Sukontasukkul Piti. "Seismic Performance Enhancement of Non-Ductile RC Columns Using Steel Fiber Reinforced Concrete (SFRC)." Advanced Materials Research 747 (August 2013): 773–76. http://dx.doi.org/10.4028/www.scientific.net/amr.747.773.
Full textAbstract:
The principal aim of this research is to improve the seismic performance of non-ductile reinforced columns using fiber reinforced concrete (FRC) by mixing steel fiber into the concrete. Two reinforced concrete columns 200mm x 300mm in cross-section with a height of 1250 mm were tested under cyclic lateral loading. The first specimen was casted using normal strength concrete of 24 MPa and the second specimens were also casted using similar concrete with similar strength but the steel fiber of 1% was added to the concrete in the plastic hinge region. The axial load for all specimens was 300 kN and kept constant during the test. The test results showed that the use of FRC in the plastic hinge region could significantly improve column displacement ductility. The maximum drift at lateral strength loss at 3.7% for non-ductile column could increase to 6% in FRC column. It is evident that the cracks in FRC column are much smaller and more widely spread in the plastic hinge region and hence the plastic hinge could be able to rotate without lateral strength being compromised. In FRC column, concrete spalling was observed in a very high drift (5%) and bar buckling occurred at around 6% drift whilst in non-ductile column concrete spalling and bar buckling occurred at 2.5% and 3% drift respectively. It was evident that the use of steel fiber in non-ductile columns could significantly improve seismic performance of the column.
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Krainskyi, Pavlo, Yaroslav Blikharskyy, Roman Khmil, and Pavlo Vegera. "Influence of loading level on the bearing capacity of RC columns strengthened by jacketing." MATEC Web of Conferences 230 (2018): 02013. http://dx.doi.org/10.1051/matecconf/201823002013.
Full textAbstract:
Compressed reinforced concrete elements are quite common in construction. An example of such elements is the columns of industrial buildings, which are loaded with eccentric force, for example, from a bridge crane, columns of multistory buildings, structures subjected to compression and bending. When the reinforced concrete structure becomes unfit to future operation, it is often more economical and easy to retrofit it than to change it for a new one. Most of these structures are influenced by certain loads and unloading the structures before strengthening is not always possible. Therefore, in this work reinforced concrete structures strengthened by jacketing are investigated. To simulate the real life conditions, the loading level of 65-70% of the not strengthened column bearing capacity was maintained during jacketing. This load level simulates the actual service load on the structure. The bearing capacity load and serviceability limit state of not strengthened and jacketed reinforced concrete columns were investigated and the experimental results are presented in this paper.