• Structural Engineering and Mechanics
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• v.22 no.3
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• pp.371-399
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• 2006

The theoretical background and capabilities of the developed program, SAR-CWF, for stochastic analysis of 3D reinforced-concrete shear wall-frame structures subject to seismic excitations is presented. Incremental stiffness and strength properties of system members are modeled by extended Roufaiel-Meyer hysteretic relation for bending while shear deformations for walls by Origin-Oriented hysteretic model. For the critical height of shear-walls, division to sub-elements is performed. Different yield capacities with respect to positive and negative bending, finite extensions of plastic hinges and P-${\delta}$ effects are considered while strength deterioration is controlled by accumulated hysteretic energy. Simulated strong motions are obtained from a Gaussian white-noise filtered through Kanai-Tajimi filter. Dynamic equations of motion for the system are formed according to constitutive and compatibility relations and then inserted into equivalent It$\hat{o}$-Stratonovich stochastic differential equations. A system reduction scheme based on the series expansion of eigen-modes of the undamaged structure is implemented. Time histories of seismic response statistics are obtained by utilizing the computer programs developed for different types of structures.

• Journal of the Earthquake Engineering Society of Korea
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• v.20 no.4
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• pp.191-199
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• 2016

Piloti-type building is one of typical vertical atypical buildings. These buildings can fail by weak-story or flexible-story mechanism on the first story. They should be designed by taking into account the special seismic load, but those less than six stories are not required to confirm the seismic performance from structural engineers in Korea. For this reason, small-size pilloti-type RC buildings need to be checked for seismic performance. Based on this background, this study performed nonlinear dynamic analysis using the PERFORM-3D for small-size pilloti-type RC buildings and assessed their seismic performance. Examples are two through four story buildings with and without walls in the first story. The walls and columns in the first story satisfied the target performance in the basic of flexural behavior due to quite a large size and reinforcement. However, wall shear demands exceed shear strength in some buildings. When designed for KBC2009, wall shear strength exceed shear demand in some buildings, but still does not in others. Consequently, wall shear must be carefully checked in both existing and new small-size pilloti-type RC buildings.

• Journal of the Korean Society of Safety
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• v.28 no.4
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• pp.58-65
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• 2013

Transportation and further expansion of social infrastructure was needed along the development of urbanization and population concentration. To use the underground space due to the lack of availability of land, it is inevitable to intersect between present structure and tunnel during construction. Soil grouting is one of the ground improvement methods to reinforce weak soil around the underground structures by injection of grouting liquid. Some of central columns of an upper structure are damaged during injection of grouting liquid by injection pressure. To investigate and improve the stability of the tunnel, three dimensional analysis are performed with full construction stages which includes the construction of present underpass, damaging columns of the underpass, reinforcing the columns by H-pile and shear walls, and excavation and construct tunnel. The arrangement of grouting holes such as curtain and horizontal type affects largely to the stability of upper structure and horizontal arrangement diminish the shear forces which is the cause of damage of central columns. The liquid injection type of reinforcement for tunnel is not recommended while the presence of upper structure with columns. Wall type reinforcing is utilize for permant support of upper structures which is affected by grouting injection pressure. H-pile is utilize for temporary support, but not for permanent since the sharing of shear forces is not much to shear wall during tunnel construction.

• Journal of the Earthquake Engineering Society of Korea
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• v.3 no.2
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• pp.29-40
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• 1999

This study presents a simplifled calculation method for required ductility of coupling beams in precast coupled shear walls at preliminary seismic design stages. Deflection of precast coupled shear walls based on a continuum approach is combined with inelastic gap opening of horizontal connection of panels to provide a relationship between the system-level ductility and the element-level ductility in a precast coupled shear wall. The equation proposed herein for ductility requirement for coupling beams shows that higher stiffness and lower strength of coupling beams result in high ductility reuqirement. The equation also shows that the ductility requirement is proportional to the degree of gap opening of the story in question. However, the coupling beam ductility in higher stories are not affected by gap openings of horizontal connections of panel.

• Journal of the Earthquake Engineering Society of Korea
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• v.27 no.2
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• pp.91-99
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• 2023

Structural vibration induced by earthquake hazards is one of the most significant concerns in structure performance-based design. Structural hazards evoked from seismic events must be properly identified to make buildings resilient enough to withstand extreme earthquake loadings. To investigate the effects of combined earthquake-resistant systems, shear walls and five types of dampers are incorporated in nineteen structural models by altering their arrangements. All the building models were developed as per ACI 318-14 and ASCE 7-16. Seismic fragility curves were developed from the incremental dynamic analyses (IDA) performed by using seven sets of ground motions, and eventually, by following FEMA P695 provisions, the collapse margin ratio (CMR) was computed from the collapse curves. It is evident from the results that the seismic performance of the proposed combined shear wall-damper system is significantly better than the models equipped with shear walls only. The scrutinized dual seismic resisting system is expected to be applied practically to ensure a multi-level shield for tall structures in high seismic risk zones.

• Journal of the Korea Concrete Institute
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• v.26 no.4
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• pp.421-428
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• 2014

This paper describes the experimental results of insulated concrete sandwich wall panels (CSWP) with corrugated glass fiber-reinforced polymer (GFRP) shear connectors under in-plane shear loading. Corrugated GFRP shear connectors were used to improve the thermal property of insulated CSWP and to achieve composite action between the interior and exterior concrete wall panels. Test specimens were consist of three concrete panels with two insulation layers between concrete panels and middle concrete panels was loaded in the direction of gravity. To evaluate the effects of insulation types (extruded polystyrene, XPSS and expanded polystyrene, EPS), shear connector pitch (300 and 400 mm) and width (10 and 15 mm) on in-plane shear behavior of insulted CSWP, failure mode and shear flow-average relative slip relationship of specimens were investigated. Test results indicate that the bond stress between concrete panel and insulation is considerable initially. Especially in case of insulated CSWP without shear connector, initial stiffness of CSWP with XPSS is superior to that of CSWP with EPS. The shear connector's contribution to in-plane shear performance of insulated CSWP depends on the type of insulation.

• Korea-Australia Rheology Journal
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• v.16 no.2
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• pp.75-83
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• 2004

The purpose of the present study is to investigate fluid mechanical interactions between two major abdominal aortic branches under both steady and pulsatile flow conditions. Two model branching systems are considered: two branches emerging off the same side of the aorta (model 1) and two branches emerging off the opposite sides of the aorta (model 2). At higher Reynolds numbers, the velocity profiles within the branches in model 1 are M-shaped due to the strong skewness, while the loss of momentum in model 2 due to turning effects at the first branch leads to the absence of a reversed flow region at the entrance of the second branch. The wall shear stresses are considerably higher along the anterior wall of the abdominal aorta than along the posterior wall, opposite the celiac-superior mesenteric arteries. The wall shear stresses are higher in the immediate vicinity of the daughter branches. The peak wall shear stress in model 2 is considerably lower than that in the model 1. Although quantitative comparisons of our results with the physiological data have not been possible, our results provide useful information for the localization of early atherosclerotic lesions.

• Journal of the Earthquake Engineering Society of Korea
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• v.17 no.2
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• pp.79-88
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• 2013

Steel plate concrete (SC) composite structure is now being recognized as a promising technology applicable to nuclear power plants as it is faster and suitable for modular construction. It is required to identify its dynamic characteristics prior to perform the seismic design of the SC structure. Particularly, the damping ratio of the structure is one of the critical design factors to control the dynamic response of structure. This paper compares the criteria for the damping ratios of each type of structures which are prescribed in the regulatory guide for the nuclear power plant. In order to identify the damping ratio of SC shear wall, this study made SC wall specimens and conducted experiments by cyclic lateral load tests and vibration tests with impact hammer. During the lateral loading test, SC wall specimens exhibited large ductile capacities with increasing amplitude of loading due to the confinement effects by the steel plate and the damping ratios increased until failure. The experimental results show that the damping ratios increased from about 6% to about 20% by increasing the load from the safe shutdown earthquake level to the ultimate strength level.

• Journal of Korean Society of Steel Construction
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• v.25 no.5
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• pp.531-541
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• 2013

This paper investigated the structural capacity of the CT shear connectors, which is a kind of the perfobond rib and functions as an anchor transferring the tension force in the joint between a composite PHC wall pile and a bottom slab. The direct pull-out test was performed for various specimens. From failure modes and load-displacement curves, it was found that transverse rebars should be placed to holes in a web to restrict pull-out failure of CT shear connectors. The results of additional tests for specimens with transverse rebars and various support lengths indicated that all specimens were failed by the tension failure of PHC pile before pull-out failure of CT shear connector and concrete pull-out failure. Thus, the CT shear connector could endure the tension force between the PHC wall pile and the bottom slab.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.2
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• pp.139-152
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• 1998

In the present study, the flow characteristics of developing laminar oscillatory flows in a square -sectional 180 deg. curved duct are investigated experimentally. The experimental study using air in a square-sectional 180 deg. curved duct is carried out to measure velocity distributions with a data acquisition and LDV (Laser Doppler Velocimetry) processing system. In this system, Rotating Machinery Resolver (RMR) and PHASE program are used to obtain the results of unsteady flows. The major flow characteristics of developing oscillatory flows are found by analyzing velocity curves, mean velocity profiles, time-averaged velocity distribution of secondary flow, wall shear stress distributions, and entrance lengths. In a lower dimensionless angular frequency, the axial velocity distribution of laminar oscillatory flow in a curved duct shows a convex shape in a central part and axial symmetry. The maximum value of wall shear stress in a lower dimensionless angular frequency is located in an outside wall, but according to increasing the dimensionless angular frequency, the maximum of wall shear stress is moved to inner wall. The entrance lengths of laminar oscillatory flows in a square-sectional 180 deg. curved duct is obtained to 90 deg. of bended angle of duct in this experimental conditions.