• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring
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• pp.275-282
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• 2000

The seismic behavior of moment connections consisting of reinforced concrete columns and steel beams is investigated based on four 2/3 scale tests of exterior beam-column joints subject to reversed cyclic loading. The major test parameters were the number of hoops the isolated concrete contribution and the use of headed studs in the joint regions between columns and beams. Their influence on the seismic response of the connections is presented and compared. Among them the CF3 specimen containing two hoops each in the joint and column regions above and below exhibited the most favourable hysteretic response. This indicates that this type of joint details can be used in the low seismic areas such as Korea.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
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• pp.173-178
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• 2002

Flat plate is susceptible to punching shear failure at the slab-column connection, which may cause catastrophic structural collapse. To prevent such brittle failure, strength and ductility of the connection should be ensured. However, since it is very difficult to experimentally simulate the actual load and boundary conditions of the flat plate system, it is not easy to obtain reliable information and data regarding to the strength and ductility of the flat plate-column edge connection. In the present study, numerical studies were performed for edge connections of continuous flat plate. The results were compared with the existing experiments, and the variations of bending moment, drift, effective width around the connection were investigated. Based on tile findings of the numerical studies, the disadvantages of current design methods were discussed.

• 한국지진공학회논문집
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• 제19권6호
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• pp.283-292
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• 2015

In the moment frame subjected to earthquake loads, beam-column joint is structurally important for ductile behavior of a system. ACI Committee 352 proposed guidelines for designing beam-column joint details. The guidelines, however, need to be updated because of the lack of data regarding several factors that may improve the performance of joints. The purpose of this study is to investigate the seismic performance of reinforced concrete exterior joints with high-strength materials and unbonded tendons. Three specimens with different joint shear demand-to-strength ratios were constructed and tested, where headed bars were used to anchor the beam bars into the joint. All specimens showed satisfactory seismic behavior including moment strength of 1.3 times the nominal moment, ductile performance (ductility factor = at least 2.4), and sufficiently large dissipated energy.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.179-184
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• 2001

The objective of this study is to clarify the seismic capacity and the characteristics in the hysteretic behavior of RC structures with nonseismic detailing. To do this, an exterior beam-column subassemblage was selected from a 10-story RC building and 6 1/3-scale specimens were manufactured with 3 variables; ⑴ with and without slab, ⑵ upward and downward direction of anchorage for the bottom bar in beams, and ⑶ with and without hoop bars in the joint region. The test results have shown that ⑴ the existence of slab increased the strength in positive and negative moment, 25% and 62%, respectively; ⑵ the Korean practice of anchorage (downward and 25 $d_{b}$ anchorage length) caused the 8% reduction of strength and the early strength degradation when compared with the case of seismic details; and ⑶ the existence of hoop bars in the joint region does not show significant difference because the size of column is much larger than that of beam.m.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.506-509
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• 2004

This paper proposes Headed bar as reinforcement of beam-column joint, and proves seismic performance and reduction of reinforcement congestion. In these case, the use of Headed bars have obvious advantages. The greatest benefit of using Headed bars is not only improved structural performance of beam-column joints, but also the ease of fabrication, construction, and placement. Three-dimensional finite element analysis model is compared with test program which was fulfilled by the proposed model with Headed bar. Also, the plastic hinge region is relocated to the center of the longitudinal beam length according to the strong column-weak beam design philosophy, so Headed bar is used as the joint reinforcement. Therefore, this paper presents results of a computer analysis of a practical solution for relocating potential beam plastic hinge regions by the placing of straight - Headed bar.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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• pp.42-45
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• 2006

This study investigated headed bar anchorage of exterior beam column joints in nuclear power plants. In nuclear power plant structures, anchorage of headed bar is recommended to satisfy ACI 349-01 App. B that are based on the Concrete Capacity Design (CCD) method. However, CCD method may lead to very conservative results for beam column joints where head is anchored within the diagonal strut and concrete is confined by transverse rebar. Compared with results of 5 joint specimens, the anchorage capacities calculated by ACI 349-01 are underestimated by 70-90%. Therefore, it is necessary to amend ACI 349-01 for the mechanical anchorage in beam column joints.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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• pp.454-457
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• 2006

This study presents a strut-and-tie model for the development of headed bars in an exterior beam-column joint with transverse reinforcements. The tensile force of a headed bar is considered to be developed by head bearing together with bond along a bonded length as a partial embedment length. The model requires construction of struts with biaxially compressed nodal zones for head bearing and fan-shaped stress fields against neighboring nodal zones for bond stresses along the bonded length. Due to the existence of transverse reinforcements, the fan-shaped stress fields are divided into direct and indirect fan-shaped stress fields. A required development length and head size of a headed bar can be optimally designed by adjusting a proportion between a bond contribution and bearing contribution.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회 논문집(II)
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• pp.851-856
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• 2000

When subjected to the strong earthquake ground motion, upper-wall lower-frame structures have high possibility of the weak-story failure in the lower frame part. Sufficient strength, energy dissipation capacity and ductility should be provided at the joint between the deep beam and the lower column. In this study, a typical structure was selected for a prototype and four 1:2.5 scaled models, representing the subassemblage including the exterior column and the deep beam, were constructed. The transverse reinforcement was designed according to ACI procedure¹ and the procedure proposed by Sheikh². The inelastic behavior of the subassemblages subjected to the cyclic lateral displacement were evaluated through investigation of the ultimate strength, ductility, load-deformation characteristics. From the test of 4 specimens, it is concluded that the specimens designed according to Sheikh's procedure revealed higher ductility than that by ACI procedure.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회 논문집(II)
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• pp.977-982
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• 2000

As a newly structural system, RCS composite system has been researched last two decades. However mechanism of exterior T-type joint for RCS composite system is not well known. This research is focus on the exterior T-type joint for RCS composite system. Specimens are designed by the ASCE guideline, tested and compared with the inner RCS joint. Test variables include face bearing plate(FBP), extended face bearing plate(E-FBP) and U-bar. The tests indicate that the strength of exterior T-type joint is higher than that of the guideline by ASCE. The U-bar has a significant effect on the joint strength and absorbing the strain energy.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(I)
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• pp.239-242
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• 2005

The purpose of this research was focused on substantiating an effects of tendon-layouts and compressed stress($=f_{pc}$) induced by post-tensioning on seismic performance of post-tensioned flat plate slab-column connection designed as non-participating system. To accomplish this purpose, an experimental research of flat plate exterior slab-column connections subjected to gravity load and reversed lateral displacement history are presented. As a result, tendon-layout is a main variable to influence failure mechanism, dissipated energy and lateral deformation capacity. Furthermore, compressed stress ($=f_{pc}$) induced by post-tensioning enhanced the seismic performance of flat plate slab.