• Journal of the Korean Wood Science and Technology
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• v.45 no.5
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• pp.640-649
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• 2017

A comparative research on the traditional standard wood walls and other light-frame wood walls is necessary to expand the base of wooden buildings and improve consumer satisfaction. Therefore, in this research we looked for new possibilities through comparison of performance between standard wood wall and newly presented staggered stud wood wall. First, the strength characteristics of staggered stud wood walls were evaluated and the those of standard wood walls were compared. The ultimate load of the standard wall was larger than that of the staggered stud wood wall, because the cross section of the wood making up the standard wood wall was larger than that of the staggered stud wood wall. However, the statistical analysis between the two groups didn't showed a significance of 95% confidence level. This means that, staggered stud wood walls have shown the possibility of replacing the standard wood wall. Because the cross-section of the stud in the staggered stud wood walls is smaller than that of the standard wall, the material can be saved. Therefore, staggerd wood stud wall is judged to be more economical than the standard wall. In addition, since the area of the insulation also increases, improvement of the heat bridge is also expected.

• Earthquakes and Structures
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• v.5 no.5
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• pp.607-624
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• 2013

In this study the seismic risk assessments of six- and twelve-story staggered wall system structures with three different structural variations were performed. The performances of staggered wall structures with added columns along the central corridor and the structures with their first story walls replaced by beams and columns were compared with those of the regular staggered wall structures. To this end incremental dynamic analyses were carried out using twenty two pairs of earthquake records to obtain the failure probabilities for various intensity of seismic load. The seismic risk for each damage state was computed based on the fragility analysis results and the probability of occurrence of earthquake ground motions. According to the analysis results, it was observed that the structures with added columns along the central corridor showed lowest probability of failure and seismic risk. The structures with their first story walls replaced by beams and columns showed lowest margin for safety.

• International Journal of Concrete Structures and Materials
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• v.11 no.2
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• pp.285-300
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• 2017

This study investigates the seismic performance of a staggered wall structure designed with conventional strength based design, and compares it with the performance of the structure designed by capacity design procedure which ensures strong column-weak beam concept. Then the seismic reinforcement schemes such as addition of interior columns or insertion of rotational friction dampers at the ends of connecting beams are validated by comparing their seismic performances with those of the standard model structure. Fragility analysis shows that the probability to reach the dynamic instability is highest in the strength designed structure and is lowest in the structure with friction dampers. It is also observed that, at least for the specific model structures considered in this study, R factor of 5.0 can be used in the seismic design of staggered wall structures with proposed retrofit schemes, while R factor of 3.0 may be reasonable for standard staggered wall structures.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.5
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• pp.397-404
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• 2012

Fragility curves show the probability of a system reaching a limit state as a function of some measure of seismic intensity. To obtain fragility curves of six and twelve story staggered wall structures with middle corridor, incremental dynamic analyses were carried out using twenty two pairs of earthquake records, and their failure probabilities for various intensity of seismic load were investigated. The performances of staggered wall structures with added columns along the central corridor and the structures with their first story walls replaced by columns were compared with those of the regular staggered wall structures. Based on the analysis results it was concluded that staggered wall structures with central columns have the largest safety margin for the same level of seismic load.

• International Journal of Concrete Structures and Materials
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• v.10 no.3
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• pp.355-371
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• 2016

In this study seismic performance of reinforced concrete staggered wall system structures were investigated and their behavior factors such as overstrength factors, ductility factors, and the response modification factors were evaluated from the overstrength and ductility factors. To this end, 5, 9, 15, and 25-story staggered wall system (SWS) structures were designed and were analyzed by nonlinear static and dynamic analyses to obtain their nonlinear force-displacement relationships. The response modification factors were computed based on the overstrength and the ductility capacities obtained from capacity envelopes. The analysis results showed that the 5- and 9-story SWS structures failed due to yielding of columns and walls located in the lower stories, whereas in the 15- and 25-story structures plastic hinges were more widely distributed throughout the stories. The computed response modification factors increased as the number of stories decreased, and the mean value turned out to be larger than the value specified in the design code.

• Tribology and Lubricants
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• v.18 no.1
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• pp.24-33
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• 2002

The basic equations are derived for the analysis of a staggered labyrinth gas seal which are generally used in high performance compressors and steam turbines. The Bulk-flow is assumed for a single cavity control volume and the flow is assumed to be completely turbulent in circumferential direction. Moody's wall-friction-factor formula is used for the calculation of wall shear stresses in the single cavity control volume. For the reaction force developed by the seal, linearized zeroth-order and first-order perturbation equations are developed for small motion about a centered position. Integration of the resultant first-order pressure distribution along and around the seal defines the rotordynamic coefficients of the staggered labyrinth gas seal. Theoretical results of leakage and rotordynamic characteristics for the staggered labyrinth gas seal are compared with those of the plain seal and see-through labyrinth seal.

• The KSFM Journal of Fluid Machinery
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• v.7 no.6 s.27
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• pp.45-54
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• 2004

Governing equations and numerical solution methods are derived for the analysis of a combination-type-staggered-labyrinth seal used in high performance steam turbines. A bulk flow is assumed for each combination-type-staggered-labyrinth cavity. Axial flow through a throttling labyrinth strip is determined by Neumann's leakage equation and circumferential flow is assumed to be completely turbulent in the labyrinth cavity. Moody's wall-friction-factor formula is used for the calculation of wall shear stresses. For the reaction force developed by the seal, linearized zeroth-order and first-order perturbation equations are developed for small motion near the centered position. Integration of the resultant first-order pressure distribution along and around the seal defines the rotordynamic coefficients of the combination-type-staggered-labyrinth seal. Theoretical results of leakage and rotordynamic characteristics for the IP4-stage seal of USC (ultra super critical) steam turbine are shown with the effect of sump pressure, the number of throttling labyrinth strip, and rotor speed.

• Journal of the Earthquake Engineering Society of Korea
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• v.16 no.3
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• pp.43-50
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• 2012

The FEMA P695 document proposed a methodology to evaluate the collapse safety of a structure and the validity of the seismic design coefficients. In this study, the seismic performance of six- and twelve-story staggered wall structures with a middle corridor was evaluated based on the FEMA P695 procedure. The analysis results of the prototype structures were compared with those of the structures with an increased coupling beam depth or an increased re-bar ratio of the coupling beams in order to investigate the effect of retrofit. The adjusted collapse margin ratios (ACMR) of the model structures obtained from incremental dynamic analyses turned out to be larger than the specified limit states of an ACMR of 20%, which implies that the analysis model structures have enough strength against design level earthquakes. It was also observed that the increase in the re-bar ratio of the coupling beams between the staggered walls was more effective in increasing the ACMR than an increase in the depth of the coupling beams.

• Journal of computational fluids engineering
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• v.7 no.1
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• pp.10-19
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• 2002

The non-staggered(collocated) grid approach in which all the solution variables are located at the centers of control volumes is very popular for incompressible flow analyses because of its numerical efficiency on the curvilinear or unstructured grids. Rhie and Chow's paper is the first in using non-staggered grid method for SIMPLE algorithm, where pressure weighted interpolation was used to prevent decoupling of pressure and velocity. But it has been known that this non-staggered grid method has stability problems when pressure fields are nonlinear like in natural convection flows. Also Rhie-Chow scheme generates large numerical diffusion near curved walls. The cause of these unwanted problems is too large pressure damping term compared to the magnitude of face velocity. In this study the magnitude of pressure damping term of Rhie-Chow's method is limited to 1∼10% of face velocity to prevent physically unreasonable solutions. The wall pressure extrapolation which is necessary for cell-centered FVM is another source of numerical errors. Some methods are applied in a unstructured FV solver and analyzed in view of numerical accuracy. Here, two natural convection problems are solved to check the effect of the Rhie-Chow's method on numerical stability. And numerical diffusion from Rhie-Chow's method is studied by solving the inviscid flow around a circular cylinder.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.20 no.1
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• pp.37-50
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• 2016

A large eddy simulation (LES) of a turbulent channel flow is performed by using the third order low-storage Runge-Kutta method in time and second order finite difference formulation in space with staggered grid at a Reynolds number, $Re_{\tau}=590$ based on the channel half width, ${\delta}$ and wall shear velocity, $u_{\tau}$. To reduce the calculation cost of LES, algebraic wall model (AWM) is applied to approximate the near-wall region. The computation is performed in a domain of $2{\pi}{\delta}{\times}2{\delta}{\times}{\pi}{\delta}$ with $32{\times}20{\times}32$ grid points. Standard Smagorinsky model is used for subgrid-scale (SGS) modeling. Essential turbulence statistics of the flow field are computed and compared with Direct Numerical Simulation (DNS) data and LES data using no wall model. Agreements as well as discrepancies are discussed. The flow structures in the computed flow field have also been discussed and compared with LES data using no wall model.