• Computational Structural Engineering
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• v.10 no.4
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• pp.281-290
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• 1997

Current seismic design code is based on the assumption that the designed structures would be behaved inelastically during a severe earthquake ground motion. For this reason, seismic design forces calculated by seismic codes are much lower than the forces generated by design earthquakes which makes structures responding elastically. Present procedures for calculating seismic design forces are based on the use of elastic spectra reduced by a strength reduction factors known as "response modificaion factor". Because these factors were determined empirically, it is difficult to know how much inelastic behaviors of the structures exhibit. In this study, lateral strength required to maintain target ductility ratio was first calculated from nonlinear dynamic analysis of the single degree of freedom system. At the following step, base shear foeces specified in seismic design code compare with above results. If the base shear force required to maintain target ductility ratio was higher than the code specified one, the lack of required strength should be filled by overstrength and/or redundancy. Therefore, overstrength of moment resisting frame structure will be estimated from the results of push-over analysis.

• Structural Engineering and Mechanics
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• v.52 no.2
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• pp.427-443
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• 2014

This paper presents detailed analysis of the internal forces of interior beam-column joints of reinforced concrete (RC) frames under seismic action, identifies critical joint sections, proposes consistent definitions of average joint shear stress and average joint shear strain, derives formulas for calculating average joint shear and joint torque, and reports simplified analysis of the effects of joint shear and torque on the flexural strengths of critical joint sections. Numerical results of internal joint forces and flexural strengths of critical joint sections are presented for a pair of concentric and eccentric interior connections extracted from a seismically designed RC frame. The results indicate that effects of joint shear and torque may reduce the column-to-beam flexural strength ratios to below unity and lead to "joint-yielding mechanism" for seismically designed interior connections. The information presented in this paper aims to provide some new insight into the seismic behavior of interior beam-column joints and form a preliminary basis for analyzing the complicated interaction of internal joint forces.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.53-56
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• 2008

A reinforced concrete (RC) cast-in-place (CIP) infill wall retrofitting method may provide an improved seismic performance and economical efficiency for the non-ductile rahmen structures. In this study, four one story-one bay non-ductile frame were constructed and retrofitted with CIP infill wall to evaluate seismic performance of CIP infill wall-frame. From the test results, infill wall-frame exhibited a marked increase in shear strength compared to non-ductile RC frame specimen. But the ductility and story-drift at maximum load were decreased when shear strength of infill wall larger than that of existing RC frame. Therefore, it is confirmed that adequate reinforcement detail is required to assure sufficient seismic performance.

• Steel and Composite Structures
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• v.24 no.1
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• pp.1-13
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• 2017

In order to improve the deformation capacity of the high-strength concrete shear wall, five high-strength concrete shear wall specimens confined with high-strength rectangular spiral reinforcement (HRSR) possessing different parameters, were designed in this paper. One specimen was only adopted high-strength rectangular spiral hoops in embedded columns, the rest of the four specimens were used high-strength rectangular spiral hoops in embedded columns, and high-strength spiral horizontal distribution reinforcement were used in the wall body. Pseudo-static test were carried out on high-strength concrete shear wall specimens confined with HRSR, to study the influence of the factors of longitudinal reinforcement ratio, hoop reinforcement form and the spiral stirrups outer the wall on the failure modes, failure mechanism, ductility, hysteresis characteristics, stiffness degradation and energy dissipation capacity of the shear wall. Results showed that using HRSR as hoops and transverse reinforcements could restrain concrete, slow load carrying capacity degeneration, improve the load carrying capacity and ductility of shear walls; under the vertical force, seismic performance of the RC shear wall with high axial compression ratio can be significantly improved through plastic hinge area or the whole body of the shear wall equipped with outer HRSR.

• Journal of the Earthquake Engineering Society of Korea
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• v.19 no.4
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• pp.173-181
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• 2015

In this study, material tests were performed on the masonry specimens constructed with bricks and mortar used in Korea. The specimens included two types of thickness(0.5B and 1.0B) and physical conditions (good and poor). It was shown that 1.0B specimens have 3.2~1.8 times larger shear strength than 0.5B specimens and shear strength of specimens in poor condition was 66%~38% of those in good condition. Average shear stress of masonry-infills was calculated from previous experimental studies, and relationships with failure mode, material strength of masonry, aspect ratio, and frame-to-infill strength ratio were investigated. In addition, the effects of masonry strength on the seismic performance of a masonry-infilled frame was studied using a simple example building. It can be seen that the obtained average shear stress were considerably higher than the default masonry shear strength recommended by the ASCE 41, and low values the strength of masonry does not guarantee conservative evaluation results due to the early shear failure of frame members.

• Journal of the Korea Concrete Institute
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• v.27 no.6
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• pp.625-632
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• 2015

In this study, a comparative analysis have been conducted to examine seismic reinforcement effect of a school building that is designed with a CBD (Channel Beam Damper) system supported by H-frame with existing non-seismic RC frame. As a result of experiment, seismic reinforcement specimen with CBD system showed hysteretic characteristics of a large ellipse with great energy dissipation ability and increased strength and stiffness, while non-seismic design specimen showed rapid reduction in strength and brittle shear failure at top and bottom of the left and right column. In addition, comparing the stiffness reduction between the two specimens, CBD system was effective in preventing the reduction of stiffness. Energy dissipation ability of specimen reinforced by CBD system was about 4.0 times higher than the non-reinforced specimen. Such enhancement in energy dissipation ability could be considered as the result of improved strength and deformation for further application in designing of seismic reinforcement.

• Journal of the Earthquake Engineering Society of Korea
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• v.17 no.1
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• pp.43-51
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• 2013

In this paper, analytical models for reinforced concrete shear wall systems designed based on Korean Building Code (KBC2009) are proposed, which have special and semi-special seismic details and are compared with experimental results for a verification of analytical models. In addition, semi-special seismic details aimed to improve constructability and enhance economic efficiency were proposed and evaluated. The analytical models were performed based on nonlinear static and dynamic analysis. Through the nonlinear analyses, two seismic details showed the similar seismic behavior from the cyclic test and the analytical models for the two different seismic details represented the behavior in terms of the initial stiffness, maximum strength and strength degradation. And newly proposed seismic details(semi-special) provided with similar hysterestic behavior as well as the maximum drift.

• Earthquakes and Structures
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• v.23 no.3
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• pp.271-282
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• 2022

Seismic resisting self-centering bridge piers with high energy dissipation and negligible residual displacement after an earthquake event are focus topics of current structural engineering. The energy dissipation components of typical bridge piers are often relatively single; and exhibit a certain level of damage under earthquakes, leading to large residual displacements and low cumulative energy dissipation. In this paper, a novel socket self-centering bridge pier with a hybrid energy dissipation system is proposed. The seismic resilience of bridge piers can be improved through the rational design of annular grooves and rubber cushions. The seismic response was evaluated through the finite element method. The effects of rubber cushion thickness, annular groove depth, axial compression ratio, and lateral strength contribution ratio of rubber cushion on the seismic behavior of bridge piers are systematically studied. The results show that the annular groove depth has the greatest influence on the seismic performance of the bridge pier. Especially, the lateral strength contribution ratio of the rubber cushion mainly depends on the depth of the annular groove. The axial compression ratio has a significant effect on the ultimate bearing capacity. Finally, the seismic design method is proposed according to the influence of the above research parameters on the seismic performance of bridge piers, and the method is validated by an example. It is suggested that the range of lateral strength contribution ratio of rubber cushion is 0.028 ~ 0.053.

• Journal of the Korean Society of Safety
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• v.17 no.2
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• pp.76-84
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• 2002

The seismic behaviors of steel moment connections with different structural characteristics are investigated. The rupture index, which represents the fracture potential, is adopted to study the effect of concrete slab and the relative strength between the coin the beam, and Panel zone on the ductility of connections. The results show that the presence of slab increases the beam strength, imposes constraint near the beam top flange, and consequently, induces concentrated deformation near the beam access hall, which reduces the ductility of the connection. The total deformation capacity of the connection depends not only on the beam but also on the column and panel zone. Therefore, the detrimental slab effects and the relative strength should be considered in the seismic design of the connection.

• Structural Engineering and Mechanics
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• v.31 no.1
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• pp.93-112
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• 2009

In this study seismic analyses of steel structures were carried out to examine the effect of ground motion characteristics and structural properties on energy demands using 100 earthquake ground motions recorded in different soil conditions, and the results were compared with those of previous works. Analysis results show that ductility ratios and the site conditions have significant influence on input energy. The ratio of hysteretic to input energy is considerably influenced by the ductility ratio and the strong motion duration. It is also observed that as the predominant periods of the input energy spectra are significantly larger than those of acceleration response spectra used in the strength design, the strength demand on a structure designed based on energy should be checked especially in short period structures. For that reason framed structures with buckling-restrained-braces (BRBs) were designed in such a way that all the input energy was dissipated by the hysteretic energy of the BRBs, and the results were compared with those designed by conventional strength-based design procedure.