• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.2
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• pp.15-26
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• 2010

The purpose of this study is to develop a precast concrete structural wall system that can assure reliable seismic performance. In previous studies, the connections of precast concrete structural walls have had some problems in their seismic performance. Therefore, this research proposes precast concrete structural walls which have an improved seismic performance. One is a hybrid precast concrete structural wall that is composed of a reinforced concrete component and a precast concrete component, and another is a precast concrete wall whose reinforcements have a partially reduced section and are partially unbonded from the surrounding concrete. To evaluate the seismic performance of the proposed precast concrete structural walls, the behavior of three specimens, including a reinforced concrete wall, were subjected to reversed cyclic combined flexure and shear. According to the test results, the proposed precast concrete structural walls have reliable seismic performance.

• Journal of the Korea Concrete Institute
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• v.22 no.3
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• pp.325-333
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• 2010

In this study, new moment-resisting precast concrete beam-column joint made up of hybrid steel concrete was developed and tested. This beam-column joint is proposed for use in moderate seismic regions. It has square hollow tubular section in concrete column and connecting plate in precast U-beam. The steel elements in column and beam members were connected using bolt. Furthermore, in order to prevent the premature failure of concrete in hybrid steel-concrete connection, ECC(engineered cementitious composite) was used. An experimental study was carried out investigating the joint behavior subjected to reversed cyclic loading and constant axial compressive load. Two precast beam-column joint specimens and monolithic reinforced concrete joint specimen were tested. The variables for interior joints were cast-in-situ concrete area and transverse reinforcement within the joint. Tests were carried out under displacement controlled reverse cyclic load with a constant axial load. Joint performance is evaluated on the basis of connection strength, stiffness, energy dissipation, and displacement capacity. The test results showed that significant differences in structural behavior between the two types of connection because of different bonding characteristics between steel and concrete; steel and ECC. The proposed joint detail can induce to move the plastic hinge out of the ECC and steel plate. And proposed precast connection showed better performance than the monolithic connection by providing sufficient moment-resisting behavior suitable for applications in moderate seismic regions.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.05a
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• pp.48-49
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• 2014

Green Frame is a column-beam system that uses composite precast concrete members. Previous studies have proven this system to be not only structurally safe, constructible, and economically feasible, but also environmentally-friendly. If the computerized program is used to estimate the quantity, the result of it shall be calculated much easily, quickly and exactly than manual estimation, because precast concrete members of Green Frame has standard size and connection method between it. Therefore, this study suggest quantity survey concept for column-beam structure comprised of composite precast concrete members. Hereafter, the quantity survey of Green Frame shall be much quickly and accurate, if the system would be made based on the result of this study.

• Magazine of the Korea Concrete Institute
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• v.10 no.5
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• pp.58-66
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• 1998

• Earthquakes and Structures
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• v.24 no.2
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• pp.141-153
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• 2023

The presented paper considers infill masonry walls' influence on the seismic reliability of precast concrete frames. The recent Bojnord earthquake on May 13th, 2017 in Iran (MW 5.4) illustrated that the infill masonry walls play a crucial role in the damage extent and life safety issues of inhabitants in the precast concrete buildings. The incremental dynamic analysis (IDA) approach was used to determine the fragility curves of the represented damaged precast frame. Then, by integrating site hazard and structural fragilities, the seismic reliability of the represented precast frame was evaluated in different damage limit states. Additionally, the static pushover analysis (SPA) approach was used to assess the seismic performance assessment of the precast frame. Bare and infilled frames were modeled as 2D frames employing the OpenSees software platform. The multi-strut macro-model method was employed for infill masonry simulation. Also, a relatively efficient and straightforward nonlinear model was used to simulate the nonlinear behavior of the precast beam-column joint. The outputs show that consideration of the masonry infilled wall effect in all spans of the structural frame leads to a decrease in the possibility of exceedance of specified damage limit states in the structures. In addition, variation of hazard curves for buildings with and without consideration of infilled walls leads to a decrease in the reliability of the building's frames with masonry infilled walls. Furthermore, the lack of infill walls in the first story significantly affects the precast concrete frame's seismic reliability and performance.

• Computers and Concrete
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• v.13 no.3
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• pp.377-387
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• 2014

This paper presents an experimental study on socket base connections of precast reinforced concrete columns. The main purpose of this study is to determine socket base connection which has the closest behavior to monolithic casted column-base joints. For this purpose, six specimens having different column-socket base connection details were tested under cyclic loading. For each test, strength, stiffness, ductility and drift ratios of the specimens were determined. Test results indicated that a suggested connection type is 10%-30% stronger than the other type of connections under lateral loading. The welded connection (PC-5) had better lateral load carrying capacity and ductility. On the other hand, performance of standard connection (PC-1) which is commonly used in construction was weaker than other connections. Thus, decision of connection type should be referred not only performance but also applicability.

• Structural Engineering and Mechanics
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• v.12 no.4
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• pp.397-408
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• 2001

Bolted connections are used commonly in the precast reinforced concrete structures. In such structures, to perform structural analysis, behaviour of connections must be determined. In this study, elastic rotation stiffness of semi-rigid bolted beam connections, applied in industrial precast structures, are determined by finite element methods. The results obtained from numerical solutions are compared with an experimental study carried out for the same connections. Furthermore, stress distributions of the connection zone are determined and a reinforcement scheme is proposed. Thus, a more appropriate reinforcement arrangement for the connection zone is enabled. The connection joint of the prefabricated frame is described as rigid, hinged or elastic, and a static analysis of the frame system is performed for each case. Values of bending moments and displacements obtained from the three solutions are compared and the effects of elastic connection are discussed.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.530-533
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• 2006

This thesis investigates the behavior of precast wall systems with a new vertical connection which are proportioned by the displacement based design. The proposed precast wall systems are supposed to provide additional spaces and seismic strengthening in remodeling existing residential buildings. For a fast remodeling constructions using PC walls require an efficient, economic fabrication method. A C-type vertical connections for PC wall systems is proposed for transfer of bending moment between walls in the vertical direction while a shear key in the center of wall is prepared to transfer shear forces by bearing. The proposed vertical connection allows us easy fabrication because of different direction of slots at the edges of wall. The dimension of C-type connection components are determined by engineering models and a series of test.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.05a
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• pp.10-11
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• 2013

Green Frame is a column-beam system formed by composite precast concrete column and beam connected with steel buried in both members. During the installation of Green columns, the columns of Green Frame, covering 3 floors per each piece and beams, the eccentricity can be observed due to the construction error and the weight of beam itself. Such eccentricity may have a little influence on a single frame, yet, it can develop critical issues to the installation of subsequent beams or beams on the upper floors in the context of a building as a whole that has multiple frames. These issues lead to delay in frame installation, decrease of productivity and increase of cost, etc. Therefore, this study presents a steel-joint connection method in order to solve the issues. The steel-joint connection method exists on slope plane and reinforcing plate in steel frame buried in composite PC members. Through this method, the issues can be resolved without requiring additional equipment or manpower.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.11a
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• pp.169-170
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• 2011

In the connection of green frame, the bottom rebar of the precast concrete beam needs joint or anchorage to ensure structural integrity. However, given the characteristics of composite precast concrete joint, enough length over which rebar can be anchored or lap-spliced is not secured. In addition, due to issues with constructability, cost or quality, it is difficult to apply welding or mechanical connection techniques. Therefore, this study analyze the requirement for a bolt-type rebar coupler as a solution for the coupling issue between the lower rebars of green frame beam. The requirement for bolt-type rebar coupler proposed herein will provide basic data for development studies of the rebar coupler.