• Journal of the Earthquake Engineering Society of Korea
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• v.16 no.2
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• pp.25-33
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• 2012

To examine the performance of a thin plate damper attached to coupling beam of bearing wall system, 5 specimens were designed with the variable parameters of the thickness and length of a thin steel plate, which was constructed and tested with a lateral load with up to a 5% drift ratio. The result was that the total amount of the energy dissipation of the specimen with the thin plate damper was greater than that of the standard RC specimen, and the plate buckling and plastic deformation could be seen in steel plate. The shorter the length of the damper, the higher was the lateral resistant force, but there was no apparent increase in the energy dissipation. By comparison of the experiments with the elastic buckling analysis, it was shown that the buckling force from the analysis could properly estimate the maximum value of the linear elastic range.

• Steel and Composite Structures
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• v.48 no.4
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• pp.385-403
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• 2023

To avoid premature damage to the connection joints of a conventional precast concrete shear wall, a new precast concrete shear wall system (NPSW) based on a plastic damage relocation design concept was proposed. Five specimens, including one monolithic cast-in-place concrete shear wall (MSW) as a reference and four NPSWs with different connection details (TNPSW, INPSW, HNPSW, and TNPSW-N), were designed and tested by lateral low-cyclic loading. To accurately assess the damage relocation effect and quantify the damage and deformation, digital image correlation (DIC) and conventional data acquisition methods were used in the experimental program. The concrete cracking development, crack area ratio, maximum residual crack width, curvature of the wall panel, lateral displacement, and deformed shapes of the specimens were investigated. The results showed that the plastic damage relocation design concept was effective; the initial cracking occurred at the bottom of the precast shear wall panel (middle section) of the proposed NPSWs. The test results indicated that the crack area ratio and the maximum residual crack width of the NPSWs were less than those of the MSW. The NPSWs were deformed continuously; significant distortions did not occur in their connection regions, demonstrating the merits of the proposed NPSWs. The curvatures of the middle sections of the NPSWs were lower than that of the MSW after a drift ratio of 0.5%. Among the NPSWs, HNPSW demonstrated the best performance, as its crack area ratio, concrete damage, and maximum residual crack width were the lowest.

• Journal of the Earthquake Engineering Society of Korea
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• v.28 no.2
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• pp.93-101
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• 2024

Code-compliant seismic design should be essentially applied to realize the so-called emulative performance of precast concrete (PC) lateral force-resisting systems, and this study developed simple procedures to design precast industrial buildings with intermediate precast bearing wall systems considering both the effect of seismic and blast loads. Seismic design provisions specified in ACI 318 and ASCE 7 can be directly adopted, for which the so-called 1.5S_y condition is addressed in PC wall-to-wall and wall-to-base connections. Various coupling options were considered and addressed in the seismic design of wall-to-wall connections for the longitudinal and transverse design directions to secure optimized performance and better economic feasibility. On the other hand, two possible methods were adopted in blast analysis: 1) Equivalent static analysis (ESA) based on the simplified graphic method and 2) Incremental dynamic time-history analysis (IDTHA). The ESA is physically austere to use in practice for a typical industrial PC-bearing wall system. Still, it showed an overestimating trend in terms of the lateral deformation. The coupling action between precast wall segments appears to be inevitably required due to substantially large blast loads compared to seismic loads with increasing blast risk levels. Even with the coupled-precast shear walls, the design outcome obtained from the ESA method might not be entirely satisfactory to the drift criteria presented by the ASCE Blast Design Manual. This drawback can be overcome by addressing the IDTHA method, where all the design criteria were fully satisfied with precast shear walls' non-coupling and group-coupling strength, where each individual or grouped shear fence was designed to possess 1.5S_y for the seismic design.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.3 s.55
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• pp.209-216
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• 2009

Flexible frames on their own offer little resistance to lateral forces, resulting often in large deflections and rotations at the joints. On the other hand, walls subjected to lateral loads fail mainly in shear at relatively small displacements. Therefore, when the nonductile frames and wall act together, the combined action of the composite system differs significantly from that of the frame or wall alone. The objective of the study is to evaluate seismic response of infill walls with notched midsection. Reinforcement detail of wall was main variable in the experiment. Also SHCC was used in order to prevent damage concentration into notched midsection of walls. Test results, SHCC infill walls show the multiple crack patterns as expected. However, PIW-ND specimen exhibits less story drift, stiffness and energy dissipation capacity than those of PIW-NC specimen.

• International Journal of Concrete Structures and Materials
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• v.18 no.1E
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• pp.55-61
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• 2006

RC shear walls are frequently used as lateral force-resisting system in building construction because they have sufficient stiffness and strength against damage and collapse. If RC shear walls are properly designed and proportioned, these walls can also behave as ductile flexural members like cantilevered beams. To achieve this goal, the designer should provide adequate strength and deformation capacity of shear walls corresponding to the anticipated deformation level. In this study, the level of demands for deformation of shear walls was investigated using a displacement-based design approach. Also, deformation capacities of shear walls are evaluated through laboratory tests of shear walls with specific transverse confinement widely used in Korea. Four full-scale wall specimens with different wall boundary details and cross-sections were constructed for the experiment. The displacement-based design approach could be used to determine the deformation demands and capacities depending on the aspect ratio, ratio of wall area to floor plan area, flexural reinforcement ratio, and axial load ratio. Also, the specific boundary detailing for shear wall can be applied to enhance the deformation capacity of the shear wall.

• International Journal of High-Rise Buildings
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• v.5 no.1
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• pp.21-30
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• 2016

The structural efficiency of tall buildings heavily depends on the lateral stiffness and resistance capacity. Among those structural systems for tall buildings, outrigger system is one of the most common and efficient systems especially for those with relatively regular floor plan. The use of outriggers in building structures can be traced back from early 50 from the concept of deep beams. With the rise of building height, deep beams become concrete walls or now in a form of at least one story high steel truss type of outriggers. Because of the widened choice in material to be adopted in outriggers, the form and even the objective of using outrigger system is also changing. In the past, outrigger systems is only used to provide additional stiffness to reduce drift and deflection. New applications for outrigger systems now move to provide additional damping to reduce wind load and acceleration, and also could be used as structural fuse to protect the building under a severe earthquake condition. Besides analysis and member design, construction issue of outrigger systems is somehow cannot be separated. Axial shortening effect between core and perimeter structure is unavoidable. This paper presents a state-of-the-art review on the outrigger system in tall buildings including development history and applications of outrigger systems in tall buildings. The concept of outrigger system, optimum topology, and design and construction consideration will also be discussed and presented.

• Proceedings of the IEEK Conference
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• 2004.06b
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• pp.355-358
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• 2004

In this work, N-LDMOSFET(Lateral Double diffused MOSFET) was designed and fabricated on SOI(Silicon-On-Insulator) substrate, for such applications as motor controllers and high voltage switches, fuel injection controller systems in automobile and SSR(Solid State Rexay)etc. The LDMOSFET was designed to overcome the floating body effects that appear in the conventional thick SOI MOS structure by adding p+ region in source region. Also, RESURF(Reduced SURface Field) structure was proposed in this work in order to reduce a large on-resistance of LDMOSFET when operated keeping high break down voltage. Breakdown voltage was 268v in off-state ($V_{GS}$=OV) at room temperature in $22{\mu}m$ drift length LDMOSFET. When 5V of $V_{GS}$ and 30V of $V_{DS}$ applied, the on resistance(Ron), the transcon ductance($G_m$) and the threshold voltage($V_T$) was 1.76k$\Omega$, 79.7uA/V and 1.85V respectively.

• Journal of the Korean Society for Advanced Composite Structures
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• v.6 no.1
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• pp.14-20
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• 2015

In this study, we propose an innovative lateral force distribution building system between tall buildings by utilizing the difference of moment of inertia, as the alternative design for highly integrated city area. Considering a tri-axial symmetric conditions and boundary conditions for the three-dimensional building structure system, a two-dimensional model is composed. In the proposed indeterminate structural model, important design variables are determined for obtaining minimum horizontal deflections, reactions and bending moments at the ground level of the buildings. Regarding a case of the provided two spatial structures connected to 4 buildings, the optimum location of middle located spatial structure is 45% from the top of the building, which minimize the end moments at the bottom of the buildings. In the considered verification examples, reduced drifts at the top location of the building systems are validated against static wind pressure loads and static earthquake loads. The suggested hybrid building system will improve the safety and reliability of the system due to the added internal truss-dome structures in terms of more than 30% reduced drift and vibration through the development of convergence of tall buildings and spatial structures.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.05a
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• pp.257-262
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• 2002

Numerical model introduced in this study combines wave refraction-diffraction, breaking, bottom friction, lateral mixing, and critical shear stress and three sub-models for simulating waves, currents, and bottom change were briefly discussed. Simulations of beach processes and harbor sedimentation were also described at the coast neighboring Bangpo Harbor, Anmyundo, Chungnam, where the area has suffered from accumulation of drifting sand in a small fishing harbor with a wide tidal range. We also made model test for the case of a narrow tidal range at Nakdong river's estuary area to understand the effect of water level variation on the littoral drift. Simulations are conducted in terms of incident wave direction and tidal level. Characteristics of wave transformation, nearshore current, sediment transport, and bottom change are shown and analyzed. We found from the simulation that the tidal level impact to the sediment transport is very important and we should apply the numerical model with different water level to analyze sediment transport mechanism correctly. Although the model study gave reasonable description of beach processes and harbor sedimentation mechanism, it is necessary to collect lots of field observation data, including waves, tides and bottom materials, etc. for better prediction.

• Earthquakes and Structures
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• v.9 no.1
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• pp.145-171
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• 2015

Due to earthquakes, many structures suffered extensive damages that were attributed to the torsional effect caused by mass, stiffness or strength eccentricity. Due to this type of asymmetry torsional moments are generated that are imposed by means of additional shear forces developed at the vertical resisting structural elements of the buildings. Although the torsional effect on the response of reinforced concrete buildings was the subject of extensive research over the last decades, a quantitative index measuring the amplification of the shear forces developed at the vertical resisting elements due to lateral-torsional coupling valid for both elastic and elastoplastic response states is still missing. In this study a reliable index capable of assessing the torsional effect is proposed. The performance of the proposed index is evaluated and its correlation with structural response quantities like displacements, interstorey drift, base torque, shear forces and upper diaphragm's rotation is presented. Torsionally stiff, mass eccentric single-story and multistory structures, subjected to bidirectional excitation, are considered and nonlinear dynamic analyses are performed using natural records selected for three hazard levels. It was found that the proposed index provides reliable prediction of the magnitude of torsional effect for all test examples considered.