Hyoung-Seop Kim

Flexural Test for Prefabricated Composite Columns Using Steel Angle and Reinforcing Bar

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.

Cyclic Loading Test for Beam-Column Connections of Concrete-Filled U-Shaped Steel Beams and Concrete-Encased Steel Angle Columns

AbstractPrefabricated steel–reinforced concrete angle columns and concrete-filled U-shaped steel beams were recently developed for efficient steel-concrete composite construction. In the present study, seismic details of TSC beam–PSRC column connections were developed, taking into consideration constructability and cost efficiency. A cyclic loading test was performed on the beam-column connections to investigate load-carrying capacity, deformation capacity, failure mode, and energy dissipation capacity. For the test parameters, the connection type (interior or exterior) and the depth of the TSC beams were considered. The test results showed that the deformation and energy dissipation capacities of the specimens satisfied the requirements for intermediate moment frames specified in the AISC standard. Further, the moment-carrying capacities predicted using plastic stress distribution were found to be in agreement with the test results. The joint shear capacities of the specimens were evaluated according to ...

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

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.

Cyclic Seismic Testing of Composite Concrete-Filled U-Shaped Steel Beam to H-Shaped Column Connections

In this study, the cyclic seismic performance of a concrete-filled U-shaped steel beam to H-shaped steel column connections was experimentally evaluated. The concrete-filled U-shaped steel beams were compositely attached to the concrete floor slab. The test was conducted in two stages. The first testing program was carried out on one-sided moment connections to find the most promising connecting scheme. The strengthening scheme, or welding steel plates to the beam bottom flange with minimized stress concentration, was shown to be the most satisfactory, and it was used in the second-stage test on two full-scale cruciform specimens. Considering the unique constructional nature of the proposed composite connections, the critical limit states such as weld fracture, local buckling, concrete crushing, and rebar buckling were carefully addressed in designing specimens. Test results showed that the connection details and design procedures proposed in this study can successfully control the critical limit states mentioned previously. The proposed connection detail successfully pushed the plastic hinging to the tip of the strengthened zone as intended in design, thus effectively protecting the more vulnerable beam-to-column welded joint. The specimens typically exhibited a maximum story drift capacity of more than 5.5% rad, exceeding the minimum limit of 4% rad required of special moment frames. Four of the five specimens tested in this study eventually failed because of a low-cycle fatigue fracture across the beam bottom flange at a high story drift greater than 5.0% rad.

Seismic Performance Test of TSC Composit Beam to CRC Composit Column Connections

The Centrifugal Reinforced Concrete(CRC) column developed by SEN Engineering is a method utilizing PHC(Prestressed High Strength Pre-Stressed Concrete) piles as columns. The CRC column is able to obtain the maximum capacity as for a reinforced concrete column due to its manufacturing method using centrifugal force to produce high strength concrete same for PHC and inserting a reinforced cage instead of a pre-stressed wire decreasing compressive strength in PHC. This expeditious and economical way to produce concrete of strength more than 80MPa by centrifugal casting makes CRC columns be easily and quickly applied to the construction site than PC(Precast Concrete). CRC column is not only improve applicability but it also enhances constructability because its buckling capacity higher than H-section column leads to increase the depth of penetration. If a required service load is higher than the capacity of the CRC column, it can be reinforced by additional concrete casting with re-bars in the site to obtain sufficient strength. The seismic resistance performance of the CRC column-to-TSC beam connection is previously demonstrated in accordance with KBC 2009 by experimental test, and the real scale test of the connection is conducted in this study. As a result, the seismic resistance performance of the connection meets the requirements of KBC2009; therefore, the CRC column-to-TSC beam connection can be used as IMF or SMF.