• Journal of the Korea Concrete Institute
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• v.27 no.6
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• pp.591-602
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• 2015

In this paper, cyclic loading test was performed to evaluate the seismic performance of the steel coupling beam and RC shear wall. The test parameter was reinforcement detail of the shear wall. For the shear wall which was designed in accordance with the current design codes, a premature bearing failure occurred at the face of the wall. On the other hand, the bearing failure of walls was prevented due to the new type of reinforcement details. Test results indicated that the vertical reinforcements were more affected to the shear strength of the coupled shear wall than the horizontal reinforcement. Based on the failure mode, concrete stress distribution above and below flanges of the embedded steel beam was proposed. Assuming proposed concrete stress distribution, load resistance was predicted and it was agree well with test data.

• Journal of the Korea Concrete Institute
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• v.22 no.6
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• pp.833-841
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• 2010

In this report, the test results of five reinforced concrete beam-column joint subjected to cyclic load are presented. The main purpose of the research is to investigate the influence of the steel pull-out of the beam-column joints to the shear and ductile capacity of the RC beam-column assembles. In addition, the influence of the amount of beam reinforcement to the joint shear and ductile capacity is evaluated. Test results indicate that the yield penetration of steel bar increases as the joint shear strength ratio, $V_{j1}/V_{jby}$ decreases. And the slippage of the steel bars are varied according to the region of the beam-column joints. The pull-out of the steel bars of five specimens was almost the same regardless of the joint shear strength ratio, $V_{j1}/V_{jby}$. Because it was affected by not only the yield penetration of steel bar but also the axial elongation in the plastic hinge.

• Computers and Concrete
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• v.24 no.4
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• pp.313-327
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• 2019

The purpose of the present study is to present a new approach to designing and selecting the details of multidimensional continuous RC beam by applying all strength, serviceability, ductility and other constraints based on ACI318-14 using Teaching Learning Based Optimization (TLBO) algorithm. The optimum reinforcement detailing of longitudinal bars is done in two steps. in the first stage, only the dimensions of the beam in each span are considered as the variables of the optimization algorithm. in the second stage, the optimal design of the longitudinal bars of the beam is made according to the first step inputs. In the optimum shear reinforcement, using gradient-based methods, the most optimal possible mode is selected based on the existing assumptions. The objective function in this study is a cost function that includes the cost of concrete, formwork and reinforcing steel bars. The steel used in the objective function is the sum of longitudinal and shear bars. The use of a catalog list consisting of all existing patterns of longitudinal bars based on the minimum rules of the regulation in the second stage, leads to a sharp reduction in the volume of calculations and the achievement of the best solution. Three example with varying degrees of complexity, have been selected in order to investigate the optimal design of the longitudinal and shear reinforcement of continuous beam.

• Computers and Concrete
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• v.27 no.5
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• pp.457-472
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• 2021

Reinforced concrete (RC) buildings in Taiwan have suffered failure from strong earthquakes, which was magnified by the non-ductile detailing frames. Inadequate reinforcement as a consequence of the design philosophy prior to the introduction of current standards resulted in severe damage in the column and beam-column joint (BCJ). This study establishes a finite element analysis (FEA) of the non-ductile detailing RC column, BCJ, and three-story building that was previously tested through a tri-axial shaking table test. The results were then validated to laboratory specimens having the exact same dimensions and properties. FEA simulation integrates the concrete damage plasticity model and the elastic-perfectly plastic model for steel. The load-displacement responses of the column and BCJ specimens obtained from FEA were in a reasonable agreement with the experimental curves. The resulting initial stiffness and maximum base shear were found to be a close approximation to the experimental results. Also, the findings of a dynamic analysis of the three-story building showed that the time-history data of acceleration and displacement correlated well with the shaking table test results. This indicates the FEA implementation can be effectively used to predict the RC frame performance and failure mode under seismic loads.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.6
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• pp.46-55
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• 2016

Three small scale hollow circular reinforced concrete columns(4.5 aspect ratio) were tested under cyclic lateral load with constant axial load. Diameter of section is 400 mm, hollow diameter is 200 mm. The selected test variable are transverse steel ratio. Volumetric ratio of spirals of all the columns is 0.302~0.604% in the plastic hinge region. It corresponds to 45.9~91.8% of the minimum requirement of confining steel by Korean Bridge Design Specifications, which represent existing columns not designed by the current seismic design specifications or designed by seismic concept. The final objectives of this study are to provide quantitative reference data and tendency for performance or damage assessment based on the performance levels such as cracking, yielding, steel fracture, etc. In this paper, describes mainly failure behavior, strength degradation behaviour, displacement ductility of circular reinforced concrete bridge columns with respect to test variables.

• Journal of the Korea Concrete Institute
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• v.17 no.6 s.90
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• pp.903-910
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• 2005

In recent years, fiber reinforced polymer(FRP) plates have shown a great promise as an alternative to steel plates for reinforced concrete beam rehabilitation. Reinforced concrete beams strengthened with externally bonded FRP sheets to the tension face can exhibit ultimate flexural strengths several times greater than their original strength if their bond strength is enough. Debonding failure, however, may occur before the strengthened beam can achieve its enhanced flexural strength. The purpose of this paper is to investigate the debonding failure strength of FRP-strengthened reinforced concrete beams. An analytical procedure for calculating debonding load between concrete and strengthening FRP is presented. Based on the local bond stress-slip relationship in the previous studies, uniform bond stress is assumed on the effective bond length. The analytical expressions are developed from linear elastic theory and statistical analyses of experimantal results reported in the literature. The proposed method is verified by comparisons with experimental results reported in the previous researches.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.5
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• pp.121-128
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• 2012

In this paper, nonlinear analysis for reinforced concrete structure for power transmission line is performed by considering the characteristics of the failure, which are depend on loading conditions and concrete material models. On the numerical evaluation for the failure behavior, the finite element analysis is applied. For the concrete material model, microplane model based on concrete damage is introduced. However, to describe the crack bridging effect of long and short fiber of steel fiber reinforced concrete (SFRC), tensile softening model is suggested and applied for SFRC. An numerical results by finite element technique are compared with the experiment results for box culvert specimen. Comparing on the experimental and analytical results, validity and reliability of numerical analysis are investigated.

• Structural Engineering and Mechanics
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• v.39 no.2
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• pp.241-266
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• 2011

The Self Compacting Concrete, SCC is the new generation type of concrete which is not needed to be compacted by vibrator and it will be compacted by its own weight. Since SCC is a new innovation and also the high strength self compacting concrete, HSSCC behavior is like a brittle material, therefore, understanding the strength effect on the serviceability performance of reinforced self compacting concretes is critical. For this aim, first the normal and high strength self compacting concrete, NSSCC and HSSCC was designed. Then, the serviceability performance of reinforced connections consisting of NSSCC and HSSCC were investigated. Twelve reinforced concrete connections (L = 3 m, b = 0.15 m, h = 0.3 m) were simulated, by this concretes, the maximum and minimum reinforcement ratios ${\rho}$ and ${\rho}^{\prime}$ (percentage of tensile and compressive steel reinforcement) are in accordance with the provision of the ACI-05 for conventional RC structures. This study was limited to the case of bending without axial load, utilizing simple connections loaded at mid span through a stub (b = 0.15 m, h = 0.3 m, L = 0.3 m) to simulate a beam-column connection. During the test, concrete and steel strains, deflections and crack widths were measured at different locations along each member. Based on the experimental readings and observations, the cracked moment of inertia ($I_{cr}$) of members was determined and the results were compared with some selective theoretical methods. Also, the flexural crack widths of the members were measured and the applicability for conventional vibrated concrete, as for ACI, BS and CSA code, was verified for SCCs members tested. A comparison between two Codes (ACI and CSA) for the theoretical values cracking moment is indicate that, irrespective of the concrete strength, for the specimens reported, the prediction values of two codes are almost equale. The experimental cracked moment of inertia $(I_{cr})_{\exp}$ is lower than its theoretical $(I_{cr})_{th}$ values, and therefore theoretically it is overestimated. Also, a general conclusion is that, by increasing the percentage of ${\rho}$, the value of $I_{cr}$ is increased.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.1
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• pp.13-22
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• 2015

In this study, a new RCSF (Reinforced Concrete Steel Frame) external connection method is proposed for seismic strengthening of medium-and low-rise reinforced concrete buildings. The RCSF method, proposed in this study, is capable of carrying out the seismic retrofitting construction while residents can live inside structures. The method is one of the strength design approach by retrofit which can easily increase the ultimate lateral load capacity of concrete buildings controlled by shear. The pseudo-dynamic test, designed using a existing school building in Korea, was carried out in order to verify the seismic strengthening effects of the proposed method in terms of the maximum load carrying capacity and ductility. Test results revealed that the proposed RCSF strengthening method installed in RC frame enhanced conspicuously the strength and displacement capacities, and the method can resist markedly under the large scaled earthquake intensity level.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.6
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• pp.183-190
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• 2006

From the result of this research above, it may be summed up as follows. As a summary of results from each experiment, as the test body reinforced with the carbon rods was embedded inside the concrete section and made it possible uniform movement, this study has shown that it had excellent characteristics in improving the flexural strength and ductility. Also, it was considered as the carbon-steel sheet composite plate was to exert the strength more if it would complement the adherence with the concrete.