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Park H.-G.,Seoul National University | Hwang H.-J.,Seoul National University | Lee C.-H.,Seoul National University | Park C.-H.,Seoul National University | Lee C.-N.,SEN Structural Engineers Co.
Engineering Structures | Year: 2012

Concrete filled U-shaped steel beams are used to increase the flexural strength and stiffness of the steel beams by using concrete fill. In this study, a seismic detail for the concrete filled U-shaped steel beam-RC column connection was developed. A special detail using diagonal re-bars and welded re-bar connections was used to strengthen the beam-column joints. To verify the seismic performance of the beam-column connection, two full-scale specimens were tested under cyclic loading. The test parameter was the size of the U-shaped steel beam. The depths of the composite beams were 610. mm (steel plate thickness = 6. mm) and 710. mm (steel plate thickness = 8. mm) including the slab depth of 160. mm. The test results showed that the specimens exhibited good strength, deformation, and energy dissipation capacities. The deformation capacity exceeded 4% inter-story drift ratio. The primary failure mode of the specimens was buckling and fracture of the steel plate in the beam. © 2011 Elsevier Ltd.


Kim D.-K.,SEN Structural Engineers Co.
International Journal of Concrete Structures and Materials | Year: 2016

During earthquake, reinforced concrete walls show complicated post-yield behavior varying with shear span-to-depth ratio, re-bar detail, and loading condition. In the present study, a macro-model for the nonlinear analysis of multi-story wall structures was developed. To conveniently describe the coupled flexure-compression and shear responses, a reinforced concrete wall was idealized with longitudinal and diagonal uniaxial elements. Simplified cyclic material models were used to describe the cyclic behavior of concrete and re-bars. For verification, the proposed method was applied to various existing test specimens of isolated and coupled walls. The results showed that the predictions agreed well with the test results including the load-carrying capacity, deformation capacity, and failure mode. Further the proposed model was applied to an existing wall structure tested on a shaking table. Three-dimensional nonlinear time history analyses using the proposed model were performed for the test specimen. The time history responses of the proposed method agreed with the test results including the lateral displacements and base shear. © 2016, The Author(s).


Hwang H.-J.,Hunan University | Hwang H.-J.,Seoul National University | Eom T.-S.,Dankook University | Park H.-G.,Seoul National University | And 2 more authors.
Journal of Structural Engineering (United States) | Year: 2015

Prefabricated 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 ASCE design guidelines. © 2015 American Society of Civil Engineers.


Eom T.-S.,Dankook University | Hwang H.-J.,Seoul National University | Park H.-G.,Seoul National University | Lee C.-N.,SEN Structural Engineers Co. | Kim H.-S.,SEN Structural Engineers Co.
Journal of Structural Engineering (United States) | Year: 2014

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. © 2013 American Society of Civil Engineers.


Lee C.-H.,Seoul National University | Park H.-G.,Seoul National University | Park C.-H.,Seoul National University | Hwang H.-J.,Seoul National University | And 3 more authors.
Journal of Structural Engineering (United States) | Year: 2013

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. © 2013 American Society of Civil Engineers.

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