• Computers and Concrete
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• v.22 no.3
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• pp.279-289
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• 2018

Shear walls are one of the important structural elements for bearing loads imposed on buildings due to winds and earthquakes. Composite shear walls with high lateral resistance, and high energy dissipation capacity are considered as a lateral load system in such buildings. In this paper, a composite shear wall consisting of steel faceplates, infill concrete and tie bars which tied steel faceplates together, and concrete filled steel tubular (CFST) as boundary columns, was modeled numerically. Test results were compared with the existing experimental results in order to validate the proposed numerical model. Then, the effects of some parameters on the behavior of the composite shear wall were studied; so, the diameter and spacing of tie bars, thickness and compressive strength of infill concrete, thickness of steel faceplates, and the effect of strengthening the bottom region of the wall were considered. The seismic behavior of the modeled composite shear wall was evaluated in terms of stiffness, ductility, lateral strength, and energy dissipation capacity. The results of the study showed that the diameter of tie bars had a trivial effect on the performance of the composite shear wall, but increasing the tie bars spacing decreased ductility. Studying the effect of infill concrete thickness, concrete compressive strength, and thickness of steel faceplates also showed that the main role of infill concrete was to prevent buckling of steel faceplates. Also, by strengthening the bottom region of the wall, as long as the strengthened part did not provide a support performance for the upper part, the behavior of the composite shear wall was improved; otherwise, ductility of the wall could be reduced severely.

• Journal of Biomedical Engineering Research
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• v.13 no.3
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• pp.253-262
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• 1992

The wall shear stress in the vicinity of end-to end anastomoses under steady flow condi- tions was measured using a flush-mounted hot-film anemometer(FMHFA) probe. The experi- mental measurements were in good agreement lith numerical results except In flow with low Reynolds numbers. The wall shear stress increased proximal to the anastomosis in flow from the Penrose tubing (simulating an artery) to the PTFE graft. In flow from the PTFE graft to the Penrose tubing, low wall shear stress was observed distal to the anastomosis. Abnormal distributions of wall shear stress in the vicinity of the anastomosis, resulting from the compli- ance mismatch between the graft and the host artery, might be an important factor of ANFH formation and the graft failure. The present study suggests a correlation between regions of the low wall shear stress and the development of anastomotic neointimal fibrous hyperplasia (ANFH) in end-to-end anastomoses.

• Structural Engineering and Mechanics
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• v.69 no.6
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• pp.651-665
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• 2019

Past earthquakes have shown that appropriately designed and detailed buildings with shear walls have great performance such a way that a considerable portion of inelastic energy dissipation occurs in these structural elements. A plastic hinge is fundamentally an energy diminishing means which decrease seismic input energy through the inelastic deformation. Plastic hinge development in a RC shear wall in the areas which have plastic behavior depends on the ground motions characteristics as well as shear wall details. One of the most generally used forms of structural walls is flanged RC wall. Because of the flanges, these types of shear walls have large in-plane and out-of-plane stiffness and develop high shear stresses. Hence, the purpose of this paper is to evaluate the main characteristics of these structural components and provide a more comprehensive expression of plastic hinge length in the application of performance-based seismic design method and promote the development of seismic design codes for shear walls. In this regard, the effects of axial load level, wall height, wall web and flange length, as well as various features of earthquakes, are examined numerically by finite element methods and the outcomes are compared with consistent experimental data. Based on the results, a new expression is developed which can be utilized to determine the length of plastic hinge area in the flanged RC shear walls.

• Structural Engineering and Mechanics
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• v.88 no.2
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• pp.129-140
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• 2023

To increase the stiffness and strength of a reinforced concrete shear wall, steel plates are bolted to the sides of the wall. The general behavior of a composite concrete-steel shear wall is dependent on the buckling of the steel plates that should be prevented. In this paper, the unilateral buckling of steel plates of a composite shear wall is studied using the Rayleigh-Ritz method. To model the unilateral buckling of steel plate, the restraining concrete wall is described as an elastic foundation with high stiffness in compression and zero stiffness in tension. To consider the effect of bolt connections on the plate's buckling, a constrained optimization problem is solved by using Lagrange multipliers method. This process is used to obtain the critical elastic local buckling coefficients of unilaterally-restrained steel plates with various numbers of bolts, subjected to pure compression, bending and shear loading, and the interaction between them. Using these results, the spacing between shear bolts in composite steel plate shear walls is estimated and compared with the results of the AISC seismic provisions (2016). The results show that the AISC seismic provisions(2016) are overly conservative in obtaining the spacing between shear bolts.

• Journal of the Korean Society of Visualization
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• v.20 no.2
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• pp.45-54
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• 2022

We analyzed the low wall-shear stress area in the intracranial aneurysm that occurred at an anterior communicating artery with a special emphasis on vortical structures close to the wall. We reconstructed the aneurysm model from patient CTA data. We assumed blood as an incompressible Newtonian fluid and treated the blood vessel as a solid wall. The pulsatile boundary condition was applied at the inlet of the anterior cerebral artery. From the instantaneous flow field, we computed the histogram of the wall-shear stress over the aneurysm wall and found the low wall-shear stress event (< 0.4 Pa). This extreme event was due to the low wall-shear stress area that occurred at the daughter sac. We found that the merging of two vortices induced the low wall-shear stress area; one arises from the morphological characteristics of the daughter sac, and the other is formed by a jet flow into the aneurysm sac. The latter approaches the daughter sac, which ultimately leads to the strong ejection event near the daughter sac.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.10a
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• pp.325-332
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• 2003

The tube structures act like cantilevered box beams and effectively resist lateral loads. In result, they are adopted as a high-rise buildings system. However, the shear lag in tube system prevents the idealized tube behavior such as a cantilevered box beam. Therefore, the studies on shear lag phenomena are necessarily requested. The presented papers are almost studied on framed tube structures and tube in tube structures. However, the study on the shear lag in the tube structure with core wall is lack. Thus, in this paper, the shear lag of the structure is studied. The shear lag coefficient is defined to investigate shear lag phenomena. However, existing shear lag coefficients are not adequate for understanding them. Therefore, on this study, new shear lag coefficient is suggested. In addition, the shear lag in the tube structure with core wall is analyzed by changing the five structural parameters of stiffness factor in frame, stiffness factor in wall, stiffness ratio, the number of stories and the number of bays.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.500-503
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• 2011

Blood flow simulations in an idealized carotid bifurcation model with considering wall compliance were carried out to investigate the effect of wall elasticity on the wall shear stress and wall solid stress. Canonical waveforms of flowrates and pressure in the carotid arteries were imposed for the boundary conditions. Comparing to rigid wall model, generally, we could find an increased recirculation region at the carotid bulb and an overall reduced wall shear stress. Also, there was appreciable change of flowrate and pressure waveform in longitudinal direction. Solid and wall shear stress concentration occurs at the bifurcation apex.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.185-190
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• 2002

Recently, a concern to verify the displacement capacity of shear wall has been arised to produce suitable data for the performance based design. In this paper, a process is presented In evaluate the displacement capacity of shear wall. The displacement of shear wall is expressed as the superpositopn of shear and flexural deformation. Variable crack angle truss model with a modification and existing analysis program(XTRACT) are used in calculating shear and flexural displacement, respectively. The accuracy of proposed method is evaluated by the comparison calculation results with previous test results. From the comparison, it was shown that the displacement capacity of shear wall could be well predicted by using the process.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.03a
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• pp.321-328
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• 2003

The objective of this study is to investigate the seismic response of high-rise RC bearing-wall structures with irregularity. For this purpose, three 1:12 scale 17-story reinforced concrete model structures were constructed according to the similitude law, in which the upper 15 stories have a bearing-wall system while the lower 2-story frames have three different layouts of the plan : The first one is a moment-resisting frame system, the second has a infilled shear wall with symmetric plan and the third has a infilled shear wall with eccentricity, Then, these models were subjected to a series of earthquake excitations. The test results show the followings: 1) the existence of shear wall reduced greatly shear deformation at the piloti frame, but has almost the negligible effect on the reduction of the overturning-moment angle, 2) the frame with shear wall resists most of overturning moment in severe earthquake, 3) the torsional behavior is almost independent of the translational, 4) the absorbed energy due to the overturning deformation has the largest portion in the total absorbed energy.

• Journal of Biomedical Engineering Research
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• v.21 no.4
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• pp.363-372
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• 2000

The present study investigated flow dynamics of a straight elastic blood vessel under sinusoidal flow conditions in order to understand influence of wall motion and impedance phase angle(time delay between pressure and flow waveforms) on wall shear stress distribution using computational fluid dynamics. For the straight elastic tube model considered in the our method of computation. The results showed that wall motion induced additional terms in the axial velocity profile and the pressure gradient. These additional terms due to wall motion reduced the amplitude of wall shear stress and also changed the mean wall shear stress. Te trend of the changes was very different depending on the impedance phase angle. As the wall shear stress increased. As the phase angle was reduced from 0$^{\circ}$to -90$^{\circ}$for ${\pm}$4% wall motion case, the mean wall shear stress decreased by 10.5% and the amplitude of wasll shear stress increased by 17.5%. Therefore, for hypertensive patients vulnerable state to atherosclerosis according to low and oscillatory shear stress theory.