• Journal of Korean Society of Steel Construction
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• v.17 no.5 s.78
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• pp.581-591
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• 2005

This paper proposes a design formulae that evaluates the design strength of T-joints made of cold-formed square hollow steel sections with longitudinal branch plate. The T-joints had a configuration that a branch member used to longitudinal plate to the main chord in the plane. This study focused on the branch plate T-joints governed by the main chord flange failure mode among the experimental results. Based on the test results of the longitudinal branch plate T-joint in the square hollow sections, the ultimate strength on the T-joints was defined as 1.5 times the load at 1% B the strength of joints that governed the serviceability in control for $16.7{\leq}2\gamma(B/T){\leq}31.3$ and $0.20{\leq}{\beta}(b1/B){\leq}0.75$. Existing yield line models for normal T-joints were investigated to be the main chord flange failure for the branch plate T-joint, and this proposal design formula was based on the theory of the yield line model. Finally, the value of the finite element method compared with the value of the test and theory for the T-joints verified the validity of the design formulae.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.3
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• pp.21-31
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• 2018

This paper presents an experimental investigation on the structural performance of precast ribbed panel specimens and bridge deck specimens fabricated from the panels. The panel specimens are developed for permanent deck forms of railway bridges (PSC girder). The decks of railway bridges have short lengths compared with highway bridges. Therefore, precast panels for railway bridges are different from those of highway bridges. The precast panels have ribs designed for crack control at the bottom of the sections. Two kinds of specimens were examined: one with 400-mm width and one with 1200-mm width. Three specimens of each type were fabricated, and a total of 12 specimens were tested. In this test, the ultimate load, strain of the reinforcement and concrete, crack width, deformation, and slip were measured. The structural performance of the specimens was assessed using the Korea railway bridge design code and Eurocode. All specimens met the current design criteria for structural strength and serviceability.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.6
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• pp.617-627
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• 2011

This paper presents the results of analytical simulation of shake-table responses of a 1:5 scale 10-story reinforcement concrete(RC) residential building model by using the PERFORM-3D program. The following conclusion are drawn based on the observation of correlation between experiment and analysis; (1) The analytical model simulated fairly well the global elastic behavior under the excitations representative of the earthquake with the return period of 50 years. Under the design earthquake(DE) and maximum considered earthquake(MCE), this model shows the nonlinear behavior, but does not properly simulate the maximum responses, and stiffness and strength degradation in experiment. The main reason is considered to be the assumption of elastic slab. (2) Although the analytical model in the elastic behavior closely simulated the global behavior, there were considerable differences in the distribution of resistance from the wall portions. (3) Under the MCE, the shear deformation of wall was relatively well simulated with the flexural deformation being overestimated by 10 times that of experiment. This overestimation is presumed to be partially due to the neglection of coupling beams in modeling.

• Journal of the Korea Concrete Institute
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• v.16 no.6 s.84
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• pp.733-740
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• 2004

This study presents the behaviors of the typical architectural precast prestressed concrete beams, inverted tee and rectangular beams, subjected to combined flexural and torsional loads. For this purpose, two inverted-tee beams were designed with a parking live load, $5 kN/m^2$, and a market load $12 kN/m^2$ according to the currently used typical shape in the domestic building site. Also, two rectangular beams were also designed as the same bottom dimension and area, and reinforced for similar strength as in the cases of inverted tee beams. Total of four beams were tested, under combined bending and torsion, analysed and compared. Test results showed that the cracking and ultimate flexural strength of the beams decreased under torsional loading. However, two different shaped-beams had roughly the same load resisting capacity in service and ultimate states.

• Journal of the Korea Concrete Institute
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• v.18 no.6 s.96
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• pp.729-736
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• 2006

It has been shown that many Reinforced Concrete(RC) structures designed without seismic details have experienced brittle shear failures in the beam-column joint area and resulted in large permanent deformations and structural collapse. In this study, experimental investigations into the performance of exterior reinforced concrete beam-column joints strengthened with the carbon fiber-reinforced polymer(CFRP) under cyclic loading were presented. The CFRP has been applied by choosing different combinations and locations to determine the effective way to improve structural performances of joints. Eight beam-column joints were tested to investigate behaviors of each specimen under cyclic load and to compare performances of seismic retrofit. According to the experimental study, the retrofit strengthened with the CFRP provides significant improvements of flexural capacity and ductility of beam-column joints originally built without seismic details.

• Journal of the Korea Concrete Institute
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• v.20 no.6
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• pp.785-796
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• 2008

Longitudinal elongation develops in reinforced concrete beams that exhibit flexural yielding during cyclic loading. The longitudinal elongation can decrease the shear strength and deformation capacity of the beams. In the present study, nonlinear truss model analysis was performed to study the elongation mechanism of reinforced concrete beams. The results showed that residual tensile plastic strain of the longitudinal reinforcing bar in the plastic hinge is the primary factor causing the member elongation, and that the shear-force transfer mechanism of diagonal concrete struts has a substantial effect on the magnitude of the elongation. Based on the analysis results, a simplified method for evaluating member elongation was developed. The proposed method was applied to test specimens with various design parameters and loading conditions.

• Journal of the Korea Institute of Building Construction
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• v.17 no.5
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• pp.403-409
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• 2017

In this study, mix proportioning of porous concrete with compressive strength and porosity exceeding 3MPa and 30%, respectively, was examined and then load capacity and flexural toughness of the porous concrete block were evaluated according to the different arrangements of the GFRP bars. To achieve the designed requirements of porous concrete, it can be recommended that water-to-cement ratio and cement-to-coarse aggregate ratio are 25% and 20%, respectively, under the aggregate particle distribution of 15~20mm. The failure mode of porous concrete blocks reinforced with GFRP bars was governed by shear cracks. As a result, very few flexural resistance of the GFRP was expected. However, the enhanced shear strength of porous concrete due to the dowel action of the GFRP bars increased the load capacity and toughness of the blocks. The porous concrete blocks reinforced with one GFRP bar at each compressive and tensile regions had 2.1 times higher load capacity than the companion non-reinforced block and exhibited a high ductile behavior with the ultimate toughness index ($I_{30}$) of 43.4.

• Journal of Korean Society of Steel Construction
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• v.28 no.2
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• pp.85-96
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• 2016

Double split tee connection has various strength, stiffness, and energy dissipation capacity according to changes of thickness of T-stub flange and gauge distance, number, and diameter of high-strength bolt. If the double split tee connection is applied to a low- or medium-rise steel structure, a shear tab can't be applied for supporting shear force because of geometrical limitation. So it is required to propose details of improved double split tee connection to support shear force as well as flexural force. This research was performed to see if enough rotational stiffness is found when the double split tee connection without shear tab which was obtained through analytic and experimental researches by Yang et al. is applied to a low- or medium-rise steel structure. Also, it was seen if the low- or medium-rise steel structure having double split tee connection without shear tab has safe structural behavior, as well as material saving effect.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.5
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• pp.182-189
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• 2021

VPS(Void Plywood Slab System, VPS) has optimized the shape of the hollow material. In addition, it has a function to prevent the floating of the hollow material and the separation due to the working load. In this study, the punching shear capacity of flat plate was performed using Void Plywood Slab System with form work panel proposed in the previous study. As a result of the test, the strength of the VSPS specimen in which the hollow material was placed beyond 2.0 times the column width from the loading point was reduced by 9.4% compared to the reference specimen. However, the strength value was about 1.57 times higher than the design value suggested by KBC 2016. It was found that there was no change in stiffness compared to the reference specimen until shear failure occurred in the VSPS specimen in which the hollow material was placed. It can be seen that this experiment is being destroyed by shear as the flexural reinforcing bars are sufficiently reinforced.

• Journal of the Society of Disaster Information
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• v.15 no.2
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• pp.206-213
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• 2019

Purpose: This study aims to develop eco - friendly paving materials using Sawdust and EPDM chips. Method: Materials are eco-friendly materials and have no environmental problems. By using EPDM chip, the walking feeling can be increased. Results: In this study, the optimum mixing ratio was calculated through mixing design test. Based on the blending ratio, the surface layer of the sidewalk is made of fine sawdust and EPDM chips. We used only sawdust of grain - 107 -size to make the base layer of the sidewalks and the surface layer of the bicycle road with the permeability and the anti - resilience, and suggested the application method through the test construction. Conclusion: This study the expected that the recent efforts of the government to reduce the elastic paving material, which is the environmentally harmful problem with the complete eco-friendly paving material, are expected to revive.