<DOWNLOAD>

• An integrated evaluation of productivity, cost and CO2 emission between prefabricted and conventional columns

– 저 자 : 정재욱, 홍태훈, 지창윤, 김지민, 이민현, 정광복, 이승환
The off-site prefabrication construction method offers several advantages that have positioned it as a good alternative to the conventional method. Recently in South Korea, a form-latticed prefabricated steel reinforced concrete (Form-LPSRC) column was invented as substitute for a conventional steel reinforced concrete (SRC) column. This study evaluates the productivity, cost, and CO2 emission of Form-LPSRC column with those of SRC column through a case study. Two factory projects utilizing same-size Form-LPSRC and SRC columns are studied. In addition, Web-CYCLONE simulation and equation-based methods are utilized to calculate the productivity, cost, and CO2 emission of the two column methods. In particular, Web-CYCLONE simulation is used for considering the idle time during the construction process. The Form-LPSRC column improved productivity by 42.5% and provided costs savings of 1.32% compared with the SRC column. Thus, the Form-LPSRC column is excellent for projects where construction duration and cost are of utmost importance. However, the CO2 emission of the Form-LPSRC column is 72.18% higher than that of the SRC column.

<DOWNLOAD>

• 고강도 앵글을 적용한 선조립 합성기둥의 압축 실험

– 저자 : 황현종, 엄태성, 박홍근, 이창남, 김형섭

본 연구에서는 고강도 앵글을 사용한 선조립 합성기둥(PSRC 합성기둥)을 연구하였다. 2/3 축소모델의 PSRC 실험체 및 단면 중앙부에 H형강을 매입한 일반 SRC 실험체를 제작하여 중심압축실험을 수행하였다. 강재비와 횡철근 간격을 실험 변수로 고려하였다. 실험결과 단면 코너부 앵글에 의한 콘크리트 구속효과로 인하여 PSRC 합성기둥 실험체는 일반 SRC 합성기둥과 비교하여 하중 재하능력 및 변형능력이 우수한 것으로 나타났다. 또한 KBC 2009 설계기준에 의한 공칭압축강도보다 높은 하중저항능력을 나타냈다. 기존의 횡보강 콘크리트 재료모델을 적용하여 단면해석을 수행한 결과, 초기강성, 최대강도, 최대강도 이후의 강도 및 강성 저하 등에서 실험 및 해석결과가 비교적 잘 일치하는 것으로 나타났다.

In this study, prefabricated composite columns using high-strength angles (PSRC composite column) was studied. Concentric axial loading tests were performed for 2/3 scale PSRC specimens and an conventional SRC specimen with H-steel at the center of the cross-section. The test parameters were the steel ratio of angles and the spacing of lateral re-bars. The test results showed that by placing the angles at the corners of the cross-section for confinement with provided for the core concrete, the PSRC column specimens exhibited greater load-carrying capacity and deformation capacity than those of the conventional SRC column. The axial load-carrying capacity of the PSRC columns was greater
than the prediction by KBC 2009. Using existing stress-strain relationship of confined concrete, the axial load-deformation relationship of the specimens were predicted. The numerical predictions correlated well with the test results in terms of initial stiffness, load-carrying capacity, and post-peak strength- and stiffness- degradations

<DOWNLOAD>

• 앵글과 철근을 조립한 PSRC 합성기둥의 휨 실험

– 저자 : 엄태성, 황현종, 박홍근, 이창남, 김형섭

PSRC column is a concrete encased steel angle column. In the PSRC column, the steel angles placed at the corner of the cross-section resists bending moment and compression load. The lateral re-bars welded to steel angles resist the column shear and the bond between the steel angle and concrete. In the present study, current design procedures in KBC 2009 were applied to the flexure-compression, shear, and bond design of the PSRC composite column. To verify the validity of the design method and failure mode, simply supported 2/3 scaled PSRC and correlated SRC beams were tested under two point loading. The test parameters were the steel angle ratio and lateral bar spacing. The test results showed that the bending, shear, and bond strengths predicted by KBC 2009 correlated well with the test results. The flexural strength of the PSRC specimens was much greater than that of the SRC specimen with the same steel ratio because the steel angles were placed at the corner of the column section. However, when the bond resistance between the steel angle and concrete was not sufficient, brittle failures such as bond failure of the angle, spalling of cover concrete, and the tensile fracture of lateral re-bar occurred before the development of the yield strength of PSRC composite section. Further, if the weldability and toughness of the steel angle were insufficient, the specimen was failed
by the fracture of the steel angle at the weld joint between the angle and lateral bars.

<DOWNLOAD>

• Flexural Test for Steel-Concrete Composite Members Using Prefabricated Steel Angles

-저자 : 엄태성, 황현종, 박홍근, 이창남, 김형섭

In the proposed composite [prefabricated steel-reinforced concrete (PSRC)] column, steel angles located at the corners of the cross section are weld connected with tie bars to provide a bond for the steel angles, shear resistance, and lateral confinement. In this paper, simply supported PSRC specimens were tested to investigate their flexural strength and ductility. For comparison, a conventional concrete-encased H-section specimen was also tested. The test parameters were the steel ratio of the angle section and the spacing of the tie bars. The flexural, shear, and bond strengths of the test specimens correlated well with predictions. The flexural strength and stiffness of the PSRC specimens were significantly greater than those of the conventional composite specimen with the same steel area. However, at large inelastic deformations, the PSRC specimens were vulnerable to the bond failure between the steel angle and concrete and the tensile fracture of the angle at the weld-connection to the tie bars. When the bond strength between the steel angles and concrete was greater than the demand, the PSRC specimens exhibited ductile behavior after flexural yielding.

<DOWNLOAD>

• TSC 합성보 – PSRC 합성기둥 접합부에 대한 주기하중 실험 (Cyclic Loading Test for TSC Beam – PSRC Column Connections)

– 저자 : 황현종, 엄태성, 박홍근, 이창남, 김형섭

In the present study, details of the TSC beam-to-PSRC column connection for low and middle seismic zones were developed. For ease construction, the top and bottom flanges of the steel section of the TSC beam were discontinuous at the joint face on purpose, while the web passes through the joint. Thus, tensile resistance of the top and bottom flanges is not considered in the calculation of nominal strength of the connection. Cyclic loading tests on two interior connections and an exterior connection were performed to verify the seismic performance. The test parameter for two interior connections was the depth of the TSC beams: 600 and 700 mm including the slab depth. The test results showed that the nominal strength of the connections predicted by KBC 2009 correlated well with the test results. The connection specimens exhibited relatively good deformation and energy dissipation capacities, greater than the requirements for the ordinary and intermediate moment frames. Ultimately, the connection specimens were failed at the story drift ratios of 3.0 to 4.0 % due to local buckling and tensile fracture of the web of the TSC beam passing through the joint. By modifying the existing provisions of ASCE, the joint shear strength of the TSC beam-PSRC column connection was evaluated.

<DOWNLOAD>

• PSRC 합성기둥의 반복가력 실험 (Cyclic Loading Tests for Prefabricated Composite Columns Using Steel Angle and Reinforcing Bar)

– 저자 : 황현종, 엄태성, 박홍근, 이창남, 김형섭

PSRC composite column is a concrete encased steel angle column. In the PSRC composite column, the steel angles placed at the corner of the cross-section resists bending moment and compression load. In the present study, using the performance criteria in KBC 2009, cyclic lateral loading test was performed for PSRC columns to verify the seismic performance. The test parameters were the column type, the use of continuous hoop, and the use of studs for steel angle. 2/3 scale specimens of a conventional composite column and three PSRC columns were tested. The test results showed that the load-carrying capacity predicted by KBC 2009 correlated well with the test results. The specimens also exhibited good deformation and energy dissipation capacities. After concrete cover spalling under cyclic loading, the load-carrying capacity were decreased by buckling of longitudinal bars and steel angles. When continuous hoop was used, the deformability of the PSRC column was improved, preventing early buckling of the steel angles.