• Journal of the Korea Furniture Society
• /
• v.25 no.4
• /
• pp.331-337
• /
• 2014

The purpose of this paper is to evaluate the moment resistance of glulam post-to-base connections by applying quasi-static cyclic loads. The connectors consisted of inserted plates and drifted pins according to the load direction. The connection types employed in this study were total three including two unidirectional types (H, V) and the multi-directional type (M). The moment resistance of 8 mm-plate M-type is compared to 6 mm plate. Total four types of Post-to-base connection are prepared and tested under pseudo-static reversed cyclic loading. Test results showed that the yield moment of multi-directional connection is about 2 times higher than that uni-directional connections. The ductility ratio of multi-directional connection determined by EEEP was higher that that of uni-directional connection. It was becoming higher as the thickness of plate is increased. The Finite Element Analysis was conducted to estimate the stress distribution behavior of tested connections. Results showed the failure of multi-directional type were caused by the split of pined hole and the shear failure of lifted part of post.

• Earthquakes and Structures
• /
• v.7 no.5
• /
• pp.843-859
• /
• 2014

In the present study, the seismic performance of structural walls with boundary elements confined by conventional tie hoops and steel fiber concrete (SFC) was investigated. Cyclic lateral loading tests on four wall specimens under constant axial load were performed. The primary test parameters considered were the spacing of boundary element transverse reinforcement and the use of steel fiber concrete. Test results showed that the wall specimen with boundary elements complying with ACI 318-11 21.9.6 failed at a high drift ratio of 4.5% due to concrete crushing and re-bar buckling. For the specimens where SFC was selectively used in the plastic hinge region, the spalling and crushing of concrete were substantially alleviated. However, sliding shear failure occurred at the interface of SFC and plain concrete at a moderate drift ratio of 3.0% as tensile plastic strains of longitudinal bars were accumulated during cyclic loading. The behaviors of wall specimens were examined through nonlinear section analysis adopting the stress-strain relationships of confined concrete and SFC.

• Steel and Composite Structures
• /
• v.44 no.6
• /
• pp.899-912
• /
• 2022

To study the seismic performance of the all-steel buckling-restrained brace (BRB) using the novel soft steel LY315 for core member, a total of three identical BRBs were designed and a series of experimental and numerical studies were conducted. First, monotonic and cyclic loading tests were carried out to obtain the mechanical properties of LY315 steel. In addition, the parameters of the Chaboche model were calibrated based on the test results and then verified using ABAQUS. Second, three BRB specimens were tested under cyclic loads to investigate the seismic performance. The failure modes of all the specimens were identified and discussed. The test results indicate that the BRBs exhibit excellent energy dissipation capacity, good ductility, and excellent low-cycle fatigue performance. Then, a finite element (FE) model was established and verified with the test results. Furthermore, a parametric study was performed to further investigate the effects of gap size, restraining ratio, slenderness ratio of the yielding segment, and material properties of the core member on the load capacity and energy dissipation capacity of BRBs.

• Earthquakes and Structures
• /
• v.25 no.4
• /
• pp.283-296
• /
• 2023

This paper presents experimental and numerical studies of seismic performance on reinforced concrete (RC) wide beam (WB) joints. Two RC-WB joint specimens and one conventional RC joint specimen were fabricated using the reinforcing details of longitudinal reinforcing bars in a beam as a variable, and quasi-static cyclic loading tests were performed. The results were used to compare and analyze the load-drift ratio relationship, failure mode, and seismic performance of the specimens quantitatively. In addition, a finite element (FE) analysis of the RC-WB joint was conducted, and the rationality of the FE model was validated by comparing it with the test results. Based on the FE model, a parametric study was conducted, where the ratio of longitudinal reinforcing bars placed on the outer and inner parts of the joint (𝜌_ex/𝜌_in) was a key variable. The results showed that, in the RC-WB joint, an increase of 𝜌_ex/𝜌_in leads to more severe damage to concrete, which reduces the seismic performance of the RC-WB joints.

• Steel and Composite Structures
• /
• v.18 no.4
• /
• pp.971-983
• /
• 2015

To promote greater acceptance and use of composite RCS systems, a two-bay two-story frame specimen with improved composite RCS joint details was tested in the laboratory under reversed cyclic loading. The test revealed superior seismic performance with stable load versus story drift response and excellent deformation capacity for an inter-story drift ratio up to 1/25. It was found that the failure process of the frame meets the strong-column weak-beam criterion. Furthermore, cracking inter-story drift ratio and ultimate inter-story drift ratio both satisfy the limitation prescribed by the design code. Additionally, inter-story drift ratios at yielding and peak load stage provide reference data for Performance-Based Seismic Design (PBSD) approaches for composite RCS frames. An advantage over conventional reinforced concrete and steel moment frame systems is that the displacement ductility coefficient of the RCS frame system is much larger. To conclude, the test results prove that composite RCS frame systems perform satisfactorily under simulated earthquake action, which further validates the reliability of this innovative system. Based on the test result, some suggestions are presented for the design of composite RCS frame systems.

• Proceedings of the KSME Conference
• /
• 2008.11a
• /
• pp.1527-1532
• /
• 2008

45% of the sports accidents is the knee damage and the representative case is the damage of an Anterior Cruciate Ligament (ACL) and the Posterior Cruciate Ligament(PCL). Although the past different views of ACL reconstruction comes to an agreement, the disputes of PCL is remained yet. The most important engineering approach for these various surgery techniques is accurately to understand and to evaluate the fatigue behavior depending on the stress flow and the stress distribution under the allotted load and the cyclic load, which are caused by the graft fixing device, the proximal tibia of the PCL reconstructing structure. Therefore, this study is the basic research of these above facts. The current transtibial tunnel surgery using the cadaveric Achilles tendon grafts is chosen for the various PCL reconstruction. The relationships between the slippage, the extension ratio, and the slippage ratio by the heel bone fixing method and the soft tissue fixing method of the Achilles tendon were also defined. This research will be the essential data to help the resonable operating techniques for the next PCL reconstruction.

• Computers and Concrete
• /
• v.15 no.1
• /
• pp.1-20
• /
• 2015

Many existing reinforced concrete (RC) columns in structures tend to become substandard RC ones due to updated standards or environmental changes. These substandard columns may alter the behaviors of the whole structure and therefore are in urgent need of seismic retrofitting. Owing to their superior advantages, carbon fiber reinforced polymer (CFRP) composites are widely used to retrofit RC columns. The applications mainly focus on various substandard RC columns, but few deals with substandard columns with deteriorated concrete, especially damaged by earthquake. The purpose of this paper is to investigate the seismic behaviors of CFRP reinforced partially deteriorated RC columns and to evaluate the effect of CFRP sheets on them. Six flexure-dominant columns were tested under a constant axial load and transverse cyclic displacements. It is found that the seismic behaviors of partially deteriorated columns can be recovered by wrapping CFRP sheets on them. Numerical analysis is then conducted using finite element methods and verified with experimental results. The effects of the axial load ratio, the ratio of the thickness of CFRP sheet to the column diameter, and the slenderness ratio on the seismic behaviors of CFRP reinforced RC columns are evaluated. Finally, a method is proposed to determine the required thickness of CFRP sheet.

• Steel and Composite Structures
• /
• v.32 no.3
• /
• pp.411-422
• /
• 2019

Six shear-critical square tubed steel reinforced concrete (TSRC) columns using the high-strength concrete ($f_{cu,150}=86.6MPa$) were tested under constant axial and lateral cyclic loads. The height-to-depth ratio of the short column specimens was specified as 2.6, and the axial load ratio and the number of shear studs on the steel shape were considered as two main parameters. The shear failure mode of short square TSRC columns was observed from the test. The steel tube with diagonal stiffener plates provided effective confinement to the concrete core, while welding shear studs on the steel section appeared not significantly enhancing the seismic behavior of short square TRSC columns. Specimens with higher axial load ratio showed higher lateral stiffness and shear strength but worse ductility. A modified ACI design method is proposed to calculate the nominal shear strength, which agrees well with the test database containing ten short square TSRC columns with shear failure mode from this study and other related literature.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.24 no.6
• /
• pp.59-66
• /
• 2020

Two octagonal RC bridge columns of small scale model were tested under cyclic lateral load with constant axial load. One in two specimens was solid cross section, the other was hollow cross section. The volumetric ratio of transverse spiral hoop of all specimens is 0.00206. The columns showed flexure-shear failure. Failure behavior and seismic performance were investigated. The test results showed that the structural performance of the hollow specimen such as initial crack pattern, initial stiffness, and energy dissipation performance was comparable to that of the solid specimen, but the lateral strength, ultimate displacement, energy dissipation performance of hollow specimen noticeably decreased after drift ratio of 3%.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.25 no.5
• /
• pp.191-199
• /
• 2021

In seismic design, hollow section concrete columns offer advantages by reducing the weight and seismic mass compared to concrete section RC bridge columns. However, the flexure-shear behavior and spirals strain of hollow section concrete columns are not well-understood. Octagonal RC bridge columns of a small-scale model were tested under cyclic lateral load with constant axial load. The volumetric ratio of the transverse spiral hoop of all specimens is 0.00206. The test results showed that the structural performance of the hollow specimen, such as the initial crack pattern, initial stiffness, and diagonal crack pattern, was comparable to that of the solid specimen. However, the lateral strength and ultimate displacement of the hollow specimen noticeably decreased after the drift ratio of 3%. The columns showed flexure-shear failure at the final stage. Analytical and experimental investigations are presented in this study to understand a correlation confinement steel ratio with neutral axis and a correlation between the strain of spirals and the shear resistance capacity of steel in hollow and solid section concrete columns. Furthermore, shear strength components (V_c, V_s·, V_p) and concrete stress were investigated.