• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.6
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• pp.2343-2350
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• 2013

The wave height distributions in front of a vertically perforated wall structures for obliquely incident uni-directional irregular waves are mainly investigated by using 3D hydraulic experiments. The difference and similarity of wave propagation along the plain and perforated wall structures are investigated and particularly the effects of side walls in chamber and relative chamber width are analyzed. This study shows that the wave height distribution patterns for normalized wave heights in front of structure is significantly different between the plain and perforated wall structures, and the side wall in the chamber suppresses the growth of waves.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.5 no.2
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• pp.66-75
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• 1993

Hydraulic experiments were performed in order to gain an insight into the quantitative differences between the perforated wall caisson and its solid wall counterpart in the local pressure distribution and caisson stability. The results showed that the wave forces acting on local walls were smaller in the perforated wall caisson than in the solid wall caisson. For the caisson stability, the critical weights of the perforated wall caisson also turned out to be smaller than those of the solid wall caisson. The Phenomenon was attributed to the dual effects inherent to the perforated wall caisson, which are the decrease of total horizontal force and the phase difference between the total horizontal and vertical forces.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.6B
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• pp.633-639
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• 2006

The validity of the existing formulas for the estimation of reflection coefficient of waves due to perforated wall is investigated using the result of hydraulic experiments conducted with perforated walls of various thickness. The result shows that, when the wall is thick, the energy loss coefficient is reduced to 62% of the value evaluated using the existing formula for sharp-crested orifice. The result also shows that the length of inertia resistance increases linearly as the thickness of the wall increases. The width of chamber to achieve the minimum reflection of waves decreases as the length of inertia resistance increases. Thus, the result found in the present study can be usful for the design of perforated wall.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.4
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• pp.1455-1462
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• 2013

This study examines the reflection of a partially perforated wall with single chamber by 2D and 3D hydraulic experiments. The effects of slit shape on the front wall, relative chamber width and wave steepness were discussed. For the normal incident wave condition, the reflections of horizontal slit case were lower than that of the vertical slit with the similar porosity, but the differences are not significant. When the wave steepness is relatively small, the reflection coefficients are large. In the oblique incidence, the normalized wave heights along a perforated wall with similar porosity are almost same for the vertical and horizontal slit walls and therefore the difference by slit shape can be ignored.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.3
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• pp.194-204
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• 2007

A numerical analysis and hydraulic experiments were undertaken to investigate the head loss occurring when a flow passes through vertical perforated walls. The numerical analysis applied continuity, momentum and energy equations to the control volumes that were set near the perforated wall. Non-dimensional equations were then derived to calculate both upstream depth and head loss for the given values of downstream depth and velocity. The hydraulic experiments were performed with several single and triple perforated plates varying their opening ratios and intervals. The numerical results with the single plates were compared with the experimental results, and it was shown that the contraction coefficient of the vertical line jet formed after the perforated plates relies on downstream Froude number as well as opening ratio. Based on the experimental results, empirical formulas were formulated. Finally, the formulas were applied to the triple plates sequentially from downstream side to upstream side, and it was found that in general the predicted values nicely agreed with the experimental results.

• Structural Engineering and Mechanics
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• v.36 no.3
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• pp.247-278
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• 2010

The study of the seismic vulnerability of masonry buildings requires structural properties of walls such as stiffness, ultimate load capacity, etc. In this article, a method is suggested for modeling the masonry walls under in-plane loading. At the outset, a set of analytical equations was established for determining the elastic properties of an equivalent homogeneous material of masonry. The results for homogenized unreinforced brick walls through detailed modeling were compared in different manners such as solid and perforated walls, in-plane and out-of-plane loading, etc, and it was found that this method provides suitable accuracy in estimation of the wall linear properties. Furthermore, comparison of the results of proposed modeling with experimental out coming indicated that this model considers the non linear properties of the wall such as failure pattern, performance curve and ultimate strength, and would be appropriate to establish a parametric study on those prone factors. The proposed model is complicated; therefore, efforts need to be made in order to overcome the convergency problems which will be included in this study. The nonlinear model is basically semi-macro but through a series of actions, it can be simplified to a macro model.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.6
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• pp.2317-2328
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• 2013

In this study, the effect of wave chamber slab on wave pressure along the first and second wall of the perforated caisson breakwater was investigated by performing physical experiment. The experiment was performed without and with the wave chamber slab of the perforated caisson by varying the front wall porosity. The discrepancy in magnitudes of the measured wave pressure along the both walls of the perforated caisson was apparent according to the existence of the wave chamber slab as significantly greater pressures were acquired for all the test cases when the wave chamber was closed upward by the slab. As a result, the magnitudes of the total wave force calculated by integration of the measured wave pressure also were much larger for the caisson breakwater having the wave chamber slab, exceeding the value based on the well known Takahashi's formula (Takahashi and Shimosako, 1994). With respect to the porosity of the front wall, meanwhile, higher pressures were obtained with a larger porosity, at both the first and second wall of the breakwater.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.18 no.4
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• pp.321-328
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• 2006

In the present study extensisve numerical experiments are conducted using the CFD code, FLUENT, to investigate the energy dissipation due to perforated walls for various wall-thickness and flow conditions. A new empirical formula for energy loss coefficient considering the effect of the thickness of perforated wall is obtained based on the results of computational experiments. It is found that the energy loss coefficient decreases as the wall-thickness increases and the maximum coefficient reduction reaches upto 40% of the value calculated using the conventional formulas for the sharp-crested orifice. To check the validity of the new formula the reflection coefficient of waves due to perforated wall is evaluated and compared with the results of existing theories and hydraulic experiments. The result shows that the new formula is superior to the conventional ones.

• Journal of Navigation and Port Research
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• v.38 no.5
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• pp.503-509
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• 2014

In this study, a new concept perforated breakwater is proposed, which is having resonant channels. In the channel, perforated plate is installed for dissipating wave energy induced by flow separations. The breakwater has two advantages compared with conventional perforated breakwater having wave chamber with slotted walls. One is easy to control the target wave condition for dissipating wave energy, and the other is having the high structural safety because the structural members are not exposed to impact waves, directly. To evaluate wave reflection characteristics of the proposed breakwater, numerical experiment was carried out by using Galerkin's finite element model based on the linear potential theory. The results indicated that considerable energy dissipation occurs near the resonant period of channel, and wave reflection characteristics are affected by channel shape, location and opening ratio.

• Steel and Composite Structures
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• v.29 no.6
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• pp.771-783
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• 2018

In this paper, topology optimization (TO) is applied to find a new configuration for the perforated steel plate shear wall (PSPSW) based on the maximization of reaction forces as the objective function. An infill steel plate is introduced based on an experimental model for TO. The TO is conducted using the sensitivity analysis, the method of moving asymptotes and SIMP method. TO is done using a nonlinear analysis (geometry and material) considering the buckling. The final area of the optimized plate is equal to 50% of the infill plate. Three plate thicknesses and three length-to-height ratios are defined and their effects are investigated in the TO. It indicates the plate thickness has no significant impact on the optimization results. The nonlinear behavior of optimized plates under cyclic loading is studied and the strength, energy and fracture tendency of them are investigated. Also, four steel plates including infill plate, a plate with a central circle and two types of the multi-circle plate are introduced with equal plate volume for comparing with the results of the optimized plate.