• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.05a
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• pp.175-176
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• 2012

In this study, coupler on the safety of meeting the requirements and construction and economy to satisfy the number of parts to minimize an LK-DK coupler has been developed, affordability existing reinforcing bar joint, welded joint, mechanical joints, compared with a favorable one to the understanding, and also facilitate the construction and logistics, etc. I've found that there is no additional pay because the amount of product performance through the tensile test after test, if commercialization is expected to be greater ramifications.

• KCI Concrete Journal
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• v.13 no.2
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• pp.67-74
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• 2001

In this study, a numerical model for the simulation of reinforced concrete columns subject to cyclic loading is presented. The model consists of three separate models representing concrete, reinforcing steel bars and bond-slip between a reinforcing bar and ambient concrete. The concrete model is represented by the plane stress plastic-damage model and quadrilateral finite elements. The nonlinear steel bar model embedded in truss elements is used for longitudinal and transverse reinforcing bars. Bond-slip mechanism between a reinforcing bar and ambient concrete is discretized using connection elements in which the hysteretic bond-slip link model defines the bond stress and slip displacement relation. The three models are connected in finite element mesh to represent a reinforced concrete structure. From the numerical simulation, it is shown that the proposed model effectively and realistically represents the overall cyclic behavior of a reinforced concrete column. The present plastic-damage concrete model is observed to work appropriately with the steel bar and bond-slip link models in representing the complicated localization behavior.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.297-302
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• 2002

This paper investigated the properties of flexural behavior of composite beams (end-Reinforced concrete, center-Steel concrete) according to attaching length of main bars to flange, shear reinforcing length for different types of structure. In the preceding study, structural properties of composite beams were investigated according to shear span to depth ratio, attaching method of main bars and shear reinforcing method. Based on these results, a series of experiments was carried out according to attaching length of main bar ＆ reinforcing length for different types of structure. Consequently, as attaching length of main bar and shear reinforcing length increased, composite beams represented higher strength, ductility index and stress mechanism distributed in connection zone of different types of structure.

• Structural Engineering and Mechanics
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• v.50 no.6
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• pp.741-754
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• 2014

The conventional PHC pile-footing connection is the weak part because the surface area and stiffness are sharply changed. The Composite PHC pile reinforced with the transverse shear reinforcing bars and infilled-concrete, hereafter ICP pile, has been developed for improving the flexural and shear performance. This paper investigates the cyclic behavior and performance of the ICP pile-footing connection. To investigate the behavior of the connection, one PHC and two ICP specimens were manufactured and then a series of cyclic loading tests were performed. From the test results, it was found that the ICP pile-footing connection exhibited higher cyclic behavior and connection performance compared to the conventional PHC pile-footing connection in terms of ductility ratio, stiffness degradation and energy dissipation capacity.

• Journal of the Korea Institute of Building Construction
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• v.8 no.2
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• pp.63-70
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• 2008

Reinforcing steel work plays an important role in terms of its structural performance or weight of construction cost for reinforced concrete structures. Precise estimation of re-bar quantity gives a basis for managing the reinforcing steel work effectively. However, the estimation process is still performed ineffectively based upon the expert's experience or manpower in spite of the advanced technology or improvement efforts. Therefore, the purpose of this research is to develop a prototype system for taking-off the quantity of reinforcing steel bars quickly and accurately in an order consistent with the specific members identified on the drawings. An estimate algorithm considering the connection, settlement and coating thickness of re-bars was suggested regarding to their replacement conditions which places more emphasis on constructibility. Also, this system produces the shop drawings automatically with the calculation results with work zone information.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2002.11a
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• pp.37-41
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• 2002

Lap splice is used in building construction up to recently. As buildings become higher and larger, the use of high tensile bar is increasing due to increasing in the use of high compression concrete. However the using of high tensile bar in lap splice causes eccentricity and difficulty in placing of concrete inside the form, therefore not allowing enough intervening material. Various mechanical connection are being developed but the coupler of today needs either a secondary intervening material or secondary processing that consumes much time. Therefore a coupler, needing neither a secondary intervening material nor secondary processing, was made in this study which lead to following results. (1) Breaking occurred in all experimented rebar. (2) Acquirement of tension exceeding the standard requirement. (3) Acquirement of elongation percentage within the standard requirement.

• Steel and Composite Structures
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• v.48 no.2
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• pp.131-143
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• 2023

The CFRP bar was used to achieve more ductile and durable headed-stud shear connectors in composite components. Three series of push-out tests were firstly conducted, including specimens reinforced with pure steel fibers, steel and CFRP bars. The distributed stress was measured by the commercial PPP-BOTDA (Pre-Pump-Pulse Brillouin optical time domain analysis) optical fiber sensor with high spatial resolution. A series of numerical analyses using non-linear FE models were also made to study the shear force transfer mechanism and crack response based on the test results. Test results show that the CFRP bar increases the shear strength and stiffness of the large diameter headed-stud shear connection, and it has equivalent reinforcing effects on the stud shear capacity as the commonly used steel bar. The embedded CFRP bar can also largely improve the shear force transfer mechanism and decrease the tensile stress in the transverse direction. The parametric study shows that low content steel fibers could delay the crack initiation of slab around the large diameter stud, and the CFRP bar with normal elastic modulus and the standard reinforcement ratio has good resistance to splitting crack growth in headed stud shear connectors.

• Journal of the Korea Concrete Institute
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• v.13 no.5
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• pp.516-524
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• 2001

Among many connection methods of reinforcing bar, the grout-filled splice sleeve system is very effective method of precast concrete construction due to its superior construction efficiency, such as large allowable limit to arrangement of reinforcing bars, good application of large sized reinforcing bars. In this study, totally 20 full-sited specimens were made and tested under monotonic and cyclic loading in order to extend the usage range of grout-filled splice sleeve system. The experimental variables adopted in this study are size of reinforcing bars embedded in upper and lower part of sleeve and compressive strength of filled mortar etc. After test was performed, the results were compared and analyzed with respect to previous test of author. Following main conclusions are obtained : 1) The structural performance of splice sleeve system is improved with increasing compressive strength of filled mortar. And also it was verified that the splice sleeve system with over 700 kgf/㎠ mortar compressive strength and over 6.54 development length of reinforcing bar retains the structural performance of over A class(AIJ Criteria). 2) In the case of using different size of reinforcing bars embedded in upper and lower part of sleeve, the result show that splice sleeve matching with large sized reinforcing bar must be used. And also up to 2 level smaller size of reinforcing bar compared to large reinforcing bar embedded in sleeve can be used.

• Journal of the Korean Society for Advanced Composite Structures
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• v.5 no.4
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• pp.24-35
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• 2014

An experimental study on the structural behavior of connection types between approach slab and integral abutment has been done for three typical bar connections. Typical hinge style reinforcing bar detail for its connection is preferred in order to accommodate rotation of the approach slab among engineers. However, the straight horizontal bars can be used as connection detail accomodate structural capacity. Total six specimens with three types of rebar detail are tested for direct tensile and bending load. The characteristic structural behaviors are carefully monitored and all the strain gauge data obtained are analyzed. It is shown that the structural performance of all the specimens well exceed its design allowance. Several design suggestions are given based on careful reviews on the experiment.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.6
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• pp.119-128
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• 2008

In this study, new moment-resisting precast concrete beam-column joint is proposed for moderate seismic regions. It has the connection reinforcing bars, penetrated the joint and lap-spliced with the bottom bars of precast U-shaped PC beam. To evaluate the performance for noncontact lapped splice, experimental and analytical works were conducted. Major variables for tests are the length of lap, the diameter of connection reinforcing bars, and the distance between lapped bars. Analytic research was performed nonlinear finite element method. Analytic research focused on crack pattern, load-deflection curve, comparison of internal force, evaluation of ductility strains of reinforcement bar. Results of experimental and analytical works show that the these variables has much influence on flexural strength and ductility, and joint behavior.