• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.109-112
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• 2004

It was found from the previous experimental studies that the long-term deformation of SRC columns was quite different from that of RC columns. A new approach method is needed to quantitatively predict the long-term deformation of SRC columns. In this study, the causes of the difference between the behaviors of RC and SRC columns are investigated and discussed. SRC columns exhibit a time-dependent relative humidity distribution in a cross section differently from that of RC columns due to the presence of a flange, which interferes with the moisture diffusion of concrete. This different relative humidity distribution may reduce the drying shrinkage and the drying creep in comparison with RC columns.

• Journal of the Korea Concrete Institute
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• v.18 no.1 s.91
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• pp.29-36
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• 2006

Steel reinforced concrete(SRC) columns, which have been widely employed in high-rise buildings, exhibit a time-dependent behavior because of creep and shrinkage of concrete. This long-term behavior may cause a serious serviceability problem in structural systems, so it is very important to predict the deformation due to creep and shrinkage of concrete. However, it was found from the previous experimental studies that the long-term deformation of SRC columns was quite dissimilar from that of RC columns. A new method is required to quantitatively predict the long-term deformation of SRC columns. In this study, the causes of the discrepancy between the behaviors of RC and SRC columns are investigated and discussed. SRC columns exhibit a time-dependent relative humidity distribution in a cross section differently from that of reinforced concrete(RC) columns owing to the presence of a inner steel plate, which interferes with the moisture diffusion of concrete. This relative humidity distribution may reduce the drying shrinkage and the drying creep in comparison with RC columns. Therefore it is suggested that the differential moisture distribution should be taken into account in order to reasonably predict column shortening of SRC columns.

• Structural Engineering and Mechanics
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• v.27 no.6
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• pp.697-711
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• 2007

Though extensive research has been carried out for the ultimate strength of steel reinforced concrete (SRC) members under static and cyclic load, there was only limited information on the applied analysis models. Modeling of the inelastic response of SRC members can be accomplished by using a microcosmic model. However, generally used microcosmic model, which usually contains a group of parameters, is too complicated to apply in the nonlinear structural computation for large whole buildings. The intent of this paper is to develop an effective modeling approach for the reliable prediction of the inelastic response of SRC columns. Firstly, five SRC columns were tested under cyclic static load and constant axial force. Based on the experimental results, normalized trilinear skeleton curves were then put forward. Theoretical equation of normalizing point (ultimate strength point) was built up according to the load-bearing mechanism of RC columns and verified by the 5 specimens in this test and 14 SRC columns from parallel tests. Since no obvious strength deterioration and pinch effect were observed from the load-displacement curve, hysteresis rule considering only stiffness degradation was proposed through regression analysis. Compared with the experimental results, the applied analysis model is so reasonable to capture the overall cyclic response of SRC columns that it can be easily used in both static and dynamic analysis of the whole SRC structural systems.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.97-100
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• 2004

Steel encased composite columns are widely used due to their excellent structural performance in terms of stiffness, strength, and ductility. However, experimental studies were usually for the columns having higher steel ratio $(3-4\%)$. There are two different design concepts for SRC columns. ACI-318 specifies the design strength of the column using the same concept of reinforced concrete columns. AISC-LRFD specifies the P-M diagram using the concept of steel column. In this paper, SRC columns have the steel ratio of $0.53\%\;and\;1.06\%$. From the test results, ACI-318 specifications showed better evaluation of SRC columns having low steel ratio. H beam and steel tube partially filled with concrete were embedded in concrete. Flexural tests showed considerably high ductility.

• Steel and Composite Structures
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• v.21 no.1
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• pp.157-175
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• 2016

It was found that the lateral stiffness changes obvious at the transfer position of the section configuration from SRC to RC. This particular behavior leads to that the transfer columns become as the important elements in SRC-RC hybrid structures. A comprehensive study was conducted to investigate the seismic behavior of SRC-RC transfer columns based on a low cyclic loading test of 16 transfer columns compared with 1 RC column. Test results shows three failure modes for transfer columns, which are shear failure, bond failure and bend failure. Its seismic behavior was completely analyzed about the failure mode, hysteretic and skeleton curves, bearing capacity deformation ability, stiffness degradation and energy dissipation. It is further determined that displacement ductility coefficient of transfer columns changes from 1.97 to 5.99. The stiffness of transfer columns are at the interval of SRC and RC, and hence transfer columns can play the role of transition from SRC to RC. All specimens show similar discipline of stiffness degradation and the process can be divided into three parts. Some specimens of transfer column lose bearing capacity swiftly after shear cracking and showed weak energy dissipation ability, but the others show better ability of energy dissipation than RC column.

• 한국방재학회:학술대회논문집
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• 2009.02b
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• pp.67.2-67.2
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• 2009

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.423-426
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• 2005

Steel reinforced concrete (SRC) columns, which are widely employed in high-rise buildings, exhibit particular time-dependent behavior due to creep and shrinkage of the concrete, and this behavior may cause problems related to serviceability and structural stability. SRC columns also exhibit a time-dependent, cross-sectional relative humidity distribution that differs from reinforced concrete (RC) columns, due to the presence of an inner steel plate, which interferes with the moisture diffusion of concrete. This differential moisture distribution of SRC columns may reduce the drying shrinkage and the drying creep as contrasted with RC columns. Therefore, we propose that the differential moisture distribution be taken into account to accurately predict SRC column shortening.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2005.03a
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• pp.300-307
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• 2005

Steel Reinforced Concrete (SRC) composite column has several advantage such as excellent durability, rapid construction, reduction of column section. Due to these aspect, applications of SRC columns to bridge piers are continuously increasing. For the design of relatively large SRC columns for bridge piers, it is necessary to check the current design provisions which were based on small section having higher steel ratio. In this study, seven concrete encased composite columns were fabricated and static tests were performed. Embedded steel members were a H-shape rolled beam and a partially filled steel tube. Based on the test results, the ultimate strength according to section details and local behavior were estimated. For the analysis of inelastic behavior of the SRC column, the cracked section stiffness of the columns was evaluated and compared with calculations. The stiffness of the cracked section showed that 25% of the initial value and this stiffness reduction occurred at 85% of the ultimate load in the experiments.

• Computers and Concrete
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• v.22 no.3
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• pp.261-267
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• 2018

Long-term deformation of a steel-reinforced concrete (SRC) column is different from that of a reinforced concrete (RC) column due to the different moisture distribution. Wide-flange steel in an SRC column obstructs diffusion and makes long-term deformation slower. Previous studies analyzed the characteristics of long-term deformation of SRC columns. In this study, an additional experiment is conducted to more precisely investigate the effect of wide-flange steel on the long-term deformation of SRC columns. Long-term deformation, especially creep of SRC columns with various types of wide-flange steel, is tested. Wide-flange steel for the experiment is made of thin acrylic panels that can block diffusion but does not have strength, because the main purpose of this study is to exclusively demonstrate the long-term deformation of concrete caused by moisture diffusion, not by the reinforcement ratio. Experimental results show that the long-term deformation of a SRC column develops slower than that in a RC column, and it is slower as the wide-flange steel hinders diffusion more. These experimental results can be used for analytical prediction of long-term deformation of various SRC columns. An example of the analytical prediction is provided. According to the experimental and analytical results, it is clear that a new prediction model for long-term deformation of SRC columns should be developed in further studies.

• Earthquakes and Structures
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• v.7 no.3
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• pp.317-331
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• 2014

An experimental study was performed to investigate the seismic performance of solid steel reinforced concrete (SRC) frames with special-shaped columns that are composed of SRC special-shaped columns and reinforced concrete beams. For this purpose, two models of two-bay and three-story frame, including an edge frame and a middle frame, were designed and tested. The failure process and patterns were observed. The mechanical behaviors such as load-displacement hysteretic loops and skeleton curves, load bearing capacity, drift ratio, ductility, energy dissipation and stiffness degradation of test specimens were analyzed. Test results show that the failure mechanism of solid SRC frame with special-shaped columns is the beam-hinged mechanism, satisfying the seismic design principle of "strong column and weak beam". The hysteretic loops are plump, the ductility is good and the capacity of energy dissipation is strong, indicating that the solid SRC frame with special-shaped columns has excellent seismic performance, which is better than that of the lattice SRC frame with special-shaped columns. The ultimate elastic-plastic drift ratio is larger than the limit value specified by seismic code, showing the high capacity of collapse resistance. Compared with the edge frame, the middle frame has higher carrying capacity and stronger energy dissipation, but the ductility and speed of stiffness degradation are similar. All these can be helpful to the designation of solid SRC frame with special-shaped columns.