• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2409-2421
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• 2011

This paper will present hybrid tests to a one bay-one story steel frame structure under ground excitation. A structure used in this paper for hybrid test, to evaluate performance and behavior, is divided into two models; one is numerical model with one column element, and a truss or a beam element, the other is physical substructural model with one beam-column element. All tests considered one or three degrees of freedom to implement real-time hybrid test, and two control algorithms to control hardware are used; one using MATLAB/Simulink, the other using OpenSees, OpenFresco and xPCTarget. In addition, for real-time data communication between numerical and physical substructural models SCRAMNet was used. The results of hybrid tests were compared with one of numerical analysis of numerical model with fiber force-based beam-column elements using OpenSees. Real-time hybrid tests were implemented for the validation of control system with simple structure, and then it will be extended to hybrid test for higher nonlinear or complex structure later on.

• Journal of Korean Society of Steel Construction
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• v.24 no.1
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• pp.73-80
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• 2012

The adoption of a composite beam system is regarded as a simple but effective solution because it improves the overall stiffness, strength and stability of the structure by welding shear studs. However, welding shear studs poses problems including electric shock and weld defects. Mechanical methods have emerged as an alternative to metallurgical methods for connecting the H-beam and shear connector. Four specimens were tested in order to compare the structural behavior of the proposed composite beams with that of the classical composite beam given the condition of horizontal loading. With the original composite beam (FCB-SB specimen) using stud bolts, hysteresis loops are stable, but its strength decreased with the crashing of the concrete slab around the column. The suggested composite beams using shear connectors also yielded stable hysteresis loops. Consequently, use of the suggested composite beams instead of the original composite beam are recommended.

• Journal of Korean Society of Steel Construction
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• v.21 no.4
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• pp.375-384
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• 2009

The application of the diagrid structural system has increased of late, but cyclic loadings such as winds and earthquakes cannot be fully understood through only an analytical study due to the difficulty of considering its welding property. In this study, diagrid nodes that had been scaled down to 1/5 of their full sizes were tested to find out their structural behavior under seismic or wind loads. Four specimens were used with five parameters, including the welding method and the design details. Cyclic loading tests were carried out, where a tensile load was applied to one brace member and a compression load to the other. The major failure modes in the tests were only failure of bending with tensile stress and tension failure. The welding method and the design details had no effect on the initial stiffness and yielding stress but play a significant role in the failure mode and energy dissipation, respectively.

• Journal of the Korea Concrete Institute
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• v.14 no.6
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• pp.989-1000
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• 2002

As advanced earthquake design methods using nonlinear static analysis are developed, it is required to estimate precisely the cyclic behavior of reinforced concrete members that is characterized by strength, deformability, and energy dissipation. In a recent study, a simplified method which can estimate accurately the energy dissipation capacity of flexure-dominated RC members subjected to repeated cyclic load was developed. Based on the previously developed method, in the present study, simple equations that can be used for calculating the energy dissipation capacity were derived and verified by the comparison with experimental results. Through parametric study using the proposed equations, effects of axial load, reinforcement ratio, rebar arrangement, md ductility on the dissipated energy were investigated. The proposed equations can accurately estimate the energy dissipation capacity compared with the existing empirical equations, and therefore they will be useful for the nonlinear static analysis/design methods.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.453-454
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• 2009

In this dissertation, experimental program was carried out to study the hysteretic behavior of the reinforced different floor type interior beam-column joint repeated cyclic loads under seismic actions. The test results was as follow. The reinforced interior beam-column joint, designed by the different floor type, was increased energy dissipation capacity and maximum load carrying capacity according to the increase of different floor in comparison to standard specimen. And it was also dissimilar to failure mode adjacent to joint region. energy dissipation capacity of each specimen, designed by the different floor type, was increased 1.1${\sim}$1.35 times in comparison to standard specimen.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.5
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• pp.471-482
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• 2016

In this study, we focused on a speed-up of KIESSI-3D program, which is based on FE-IE techniques, by introducing a p-version dynamic infinite element method. In order to evaluate performance of the KIESSI-3D, numerical analyses for eight real-scale SSI problems are carried out. We considered three types of KIESSI-3D numerical models whose radii of near-field soil region($r_0$)are 1.2, 1.5, and 3.0 times of basemat radius of structure(R). In addition, SSI analyses using the SASSI2010 program are carried out used for comparison of accuracy and runtime against those of the KIESSI-3D. Numerical results show that the KIESSI-3D model of $r_0=1.2R$ is enough to give accurate solution. In view of the computing speed, the new KIESSI-3D was up to 25 times faster than the old KIESSI-3D.

• Journal of Korean Society of Steel Construction
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• v.21 no.3
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• pp.257-266
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• 2009

The results of the analysis of the structural behavior of diagrid nodes that were subjected to cyclic loads such as wind and earthquakes was not fully understood due to difficulties in considering the welding type. In this study, diagrid nodes were tested to determine their behavior when they are subjected to seismic or wind loads. Five specimens were designed and fabricated. The corresponding test parameters were the welding type for each point and the length of the overlap of the side stiffener and the brace web. Tensile force was applied to one diagrid brace member, and compression force was applied to the other diagrid brace member. Cyclic loading was applied until the failure. The test showed that failures are due to axial stress from axial force and the additional bending moment of the two combined axial forces that have different directions. Tensile failure was observed from the tensile force, and local buckling was observed from the compressive force at the flange of the brace member. In addition, the welding type and the length overlap affected the initial stiffness, the yielding stress, and the energy absorption of the diagrid node.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.4
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• pp.2917-2923
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• 2015

The three dimensional inelastic response characteristics of the standard school buildings depending on hysteresis models are reviewed. Three artificial earthquake records in accordance with KBC(Korea Building Code) are used and the inelastic response characteristics such as story shear force, story drift ratio, story displacement, hinge distribution state are reviewed with four hysteresis models. As results, story shear force is increased by maximum 27% and story drift ratio is increased by maximum 30% according to hysteresis models. Modified Takeda Model shows maximum story shear and story drift raio in longitudinal and short direction, expecting higher safety. Story shear shows minimum value with Clough Model in both directions and story drift ratio shows minimum with Takeda model in longitudinal and with Clough model in short direction, so these models are expected to decrease the safety ratio.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.6
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• pp.205-214
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• 2010

Masonry structures have been used throughout the world for the construction of residential buildings. However, from a structural point of view, the masonry material is characterized by a very low tensile strength. Moreover, the bearing and shear capacity of masonry walls have been found to be vulnerable to earthquakes. In this study, to improve the seismic performance of masonry walls, hexagonal blocks were developed and six masonry walls made with hexagonal block were tested to failure under reversed cyclic lateral loading. This paper focuses on an experimental investigation of different types of wall with hexagonal blocks, i.e. walls with different hexagonal blocks and with different reinforcing bar arrangements, subjected to applied cyclic loads. The cracking, damage patterns and hysteretic feature were evaluated. Results from the hexagonal masonry wall were shown more damage reduction and less brittle failure in comparison to the existing rectangular masonry walls.

• Journal of Korean Association for Spatial Structures
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• v.10 no.3
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• pp.65-74
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• 2010

In this study, the vibration control effect according to the installation location of the sky-bridge and the difference of natural periods of the connected buildings has been investigated. To this end, 40-story and 50-story building structures connected by a sky-bridge were used as example structures and the equivalent modeling method was used. Boundary nonlinear time history analyses were performed using El Centro and Taft earthquakes to investigate the dynamic behavior of the example structures and vibration control effect of the sky-bridge. Based on numerical results, it has been shown that displacement responses can be effectively controlled as the installation floor of the sky-bridge increases and acceleration responses can be effectively reduced when the sky-bridge is installed on the mid-stories of the example building.