• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.9-12
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• 2008

The semi-rigid joint is the shape of middle that can supplement the defect of pin joints and accept the good point of rigid joints. Recently, a study on the pin joints is activated in the country, but because the study on semi-rigid joints is not many, this study tried to prove with producing test model of three shape. The test models are rigid joint HI-R, semi-rigid joint HI-S, pin joint HI-P. As a result of the test, respectively HI-R, HI-S, HI-P appeared shear failure of joint, flexure failure of the top fixing, flexure failure of the lower part slipping stair slab, and the maximum strength is measured to 51.74, 51.4, 24.63kN, the stiffness is appeared 1.58, 1.19, 0.37 respectively, The yield strength is respectively kept 44.5, 47.3, 24kN, and ductility ratio is appeared to 3.31, 2.32, 1.54, when is based on KBC code, sag of the acting service load is appeared that HI-P model is over the standard. When is based on distribution of bars strain ratio, HI-S seems similar behavior incipiently, but after the yield, the semi-rigid joint was able to be judged better than pin joint because of the stress allotment of joint internal elements.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.13 no.1
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• pp.13-24
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• 2000

Current specification prescribes that upper and lower reinforcement mat is required in the same amount to resist negative and positive moment in bridge decks. But the negative moment is much smaller than positive moment because the actual behavior of decks consists of local deflection of slab and global deflection of girder. From this study, the analysis method based on harmonic analysis and slope-deflection method was developed and verified by finite element method. The negative moment, obtained from this method, were smaller than those computed based on the KHBDC specifications as much as 40∼50% in the middle of bridge. The amount of reduction of the design negative moment was shown herein to be dependent on variable parameters as shape factor(S/L) of slab, relative stiffness ratio of girder and deck slab, and so on. This investigations indicate that the upper reinforcement mat to resist negative moment can be removed. But further experimental study is required to consider durability and serviceability. From this new design concept, the construction expense can be reduced and the problem of decreasing durability resulting from corrosion of upper reinforcement steel settled.

• Journal of the Korean Society of Clothing and Textiles
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• v.11 no.3 s.25
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• pp.89-99
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• 1987

The purpose of this present study is not only to investigate mutal relationship between the preference of clothing design and the nature of Reflectiveness-Impulsiveness, but to offer clothing design for desirably developing of child, especially of preschool children. And the practical research was performed for 166 preschool children who are in kindergarten located in Seoul and are selected according to their sex and social class. This study used Kagan's MFFT and Personality Inventory of Hwang Eung-Yeon for the test of Reflectiveness-Impulsiveness, while for the preference of clothing design used the photo deck which is showed to children. The data analysis was based on frequency, percentage, mean, standard deviation, chi-square ($x^2$) test, t-test, F-test, and Duncan's Multiple Range Test. It can be concluded that girls rather than toys, high class children rather than middle or low class children were more reflective as a general trend. The relationship between the preference of clothing design and the nature of Reflectiveness and Impulsiveness is as follows : 1. In color, reflective boy liked blue series and reflective girl liked pastel coloring series, while they disgusted red series and non-coloring series. The group of impulsiveness liked red series, while they disgusted non-coloring series. 2. In color combination, group of reflectiveness liked similar color, while group of impulsiveness liked contrasting color. 3. In texture, group of reflectiveness liked soft and shiny texture, while they disgusted thick and rough texture. Also Group of impulsiveness liked soft texture. 4. In pattern, reflective boy liked lettering pattern and reflective girl liked flower pattern, while she disgusted lettering pattern. Impulsive boy liked stripe pattern and limpulsive girl liked flower pattern. 5. In pattern size, group of reflectivenss liked small size, while group of impulsiveness liked large one. 6. In style, group of reflectiveness liked formal style.

• Smart Structures and Systems
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• v.6 no.4
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• pp.373-388
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• 2010

The updated finite element model of K$\ddot{o}$m$\ddot{u}$rhan Highway Bridge on the Firat River located on the $51^{st}$ km of Elazi$\breve{g}$-Malatya highway is obtained by using analytical and experimental results. The 2D and 3D finite element model of the bridge is created by using SAP2000 structural analyses software, and the dynamic characteristics of the bridge are determined analytically. The experimental measurements are carried out by Operational Modal Analysis Method under traffic induced vibrations and the dynamic characteristics are obtained experimentally. The vibration data are gathered from the both box girder and the deck of the bridge, separately. Due to the expansion joint in the middle of the bridge, special measurement points are selected when experimental test setups constitute. Measurement duration, frequency span and effective mode number are determined by considering similar studies in literature. The Peak Picking method in the frequency domain is used in the modal identification. At the end of the study, analytical and experimental dynamic characteristic are compared with each other and the finite element model of the bridge is updated by changing some uncertain parameters such as material properties and boundary conditions. Maximum differences between the natural frequencies are reduced from 10% to 2%, and a good agreement is found between natural frequencies and mode shapes after model updating.

• Journal of the Korean Institute of Landscape Architecture
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• v.31 no.5
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• pp.58-72
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• 2003

Rooftop greenery has been used as a way to solve urban environmental problems by creating green space in densely populated cities. This study was carried out to suggest more effective designs for roof-garden at hospitals through a post-occupancy evaluation. The roofgarden of Asan Medical Center was evaluated with regards to setting, proximate environmental context, users, and design activity by a multi-method including plan investigations, observations, in-depth interviews and questionnaires. The results are summarized as follows; the users' main activities included resting, walking, and talking. A number of users were observed at shaded spaces sitting on such things as benches, pergolas, and shelters. The satisfaction of the users showed high satisfaction level except in the amount of shade, facilities, and shelter. The variables affecting a overall satisfaction were ‘accessibility’, ‘safety’, ‘quality of surroundings’, and ‘suitability for speculation’. By comparing the design concept with using pattern, designer's intention was not reflected sufficiently in several aspects such as ‘event deck for therapy programs’, ‘grove and path’, and ‘low planters’. This study suggests some design implications; it is necessary to furnish shaded sitting places for passive behaviors and pathways for walking or a light exercise. A wind-break wall with glass windows could widen the users' views in a limited space. Natural shade like tree shade or pergola are more desirable than artificial shades. As for the vertical location of the roofgarden, the middle floor could be better than top area for accessibility. Characteristics of building and users should be considered in detail to provide distinct spaces. Proper technical standards for the greening of artificial ground should be established.

• Wind and Structures
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• v.35 no.4
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• pp.255-268
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• 2022

Light-weight or low-damped structures may encounter the unsteady galloping instability that occurs at low reduced wind speeds, where the classical quasi-steady assumption is invalid. Although this unsteady phenomenon has been widely studied for rectangular cross sections with one side perpendicular to the incidence flow, the effect of the mean wind angle of attack has not been paid enough attention yet. With four sectional models of different side ratios and geometric shapes, the presented research focuses on the effect of the wind angle of attack on unsteady galloping instability. In static tests, comparatively strong vortex shedding force was noticed in the middle of the range of flow incidence where the lift coefficient shows a negative slope. In aeroelastic tests with a low Scruton number, the typical unsteady galloping, which is due to an interaction with vortex-induced vibration and results in unrestricted oscillation initiating at the Kármán vortex resonance wind speed, was observed for the wind angles of attack that characterize relatively strong vortex shedding force. In contrast, for the wind angles of attack with relatively weak shedding force, an "atypical" unsteady galloping was found to occur at a reduced wind speed clearly higher than the Kármán-vortex resonance one. These observations are valid for all four wind tunnel models. One of the wind tunnel models (with a bridge deck cross section) was also tested in a turbulent flow with an intensity about 9%, showing only the atypical unsteady galloping. However, the wind angle of attack with the comparatively strong vortex shedding force remains the most unfavorable one with respect to the instability threshold in low Scruton number conditions.

• Wind and Structures
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• v.16 no.4
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• pp.301-322
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• 2013

Recent major post-hurricane damage assessments in the United States have reported that the most common damages result from the loss of building roof coverings and subsequent wind driven rain intrusion. In an effort to look further into this problem, this paper presents a full-scale (Wall of Wind --WoW--) investigation of external and underneath wind pressures on roof tiles installed on a low-rise building model with various gable roofs. The optimal dimensions for the low-rise building that was tested with the WOW are 2.74 m (9 ft) long, 2.13 m (7 ft) wide, and 2.13 m (7 ft) high. The building is tested with interchangeable gable roofs at three different slopes (2:12; 5:12 and 7:12). The field tiles of these gable roofs are considered with three different tile profiles namely high (HP), medium (MP), and low profiles (LP) in accordance with Florida practice. For the ridge, two different types namely rounded and three-sided tiles were considered. The effect of weather block on the "underneath" pressure that develops between the tiles and the roof deck was also examined. These tests revealed the following: high pressure coefficients for the ridge tile compared to the field tiles, including those located at the corners; considerably higher pressure on the gable end ridge tiles compared to ridge tiles at the middle of the ridge line; and marginally higher pressure on barrel type tiles compared to the three-sided ridge tiles. The weather blocking of clay tiles, while useful in preventing water intrusion, it doesn't have significant effect on the wind loads of the field tiles. The case with weather blocking produces positive mean underneath pressure on the field tiles on the windward side thus reducing the net pressures on the windward surface of the roof. On the leeward side, reductions in net pressure to a non-significant level were observed due to the opposite direction of the internal and external pressures. The effect of the weather blocking on the external pressure on the ridge tile was negligible.

• Structural Engineering and Mechanics
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• v.78 no.1
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• pp.41-52
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• 2021

Inelastic static pushover analysis has been used in the academic-research widely for seismic analysis of structures. Nowadays, the variety pushover analysis methods have been developed, including Modal pushover, Adaptive pushover, and Cyclic pushover, in which some weaknesses of the conventional pushover method have been rectified. In the conventional pushover analysis method, the effects of cumulative growth of cracks are not considered on the reduction of strength and stiffness of RC members that occur during earthquake or cyclic loading. Therefore, the Cyclic Pushover Analysis Method (CPA) has been proposed. This method is a powerful technique for seismic evaluation of regular reinforced concrete buildings in which the first mode of them is dominant. Since the bridges have different structures than buildings, their results cannot necessarily be attributed to bridges, and more research is needed. In this study, a cyclic pushover analysis with four loading protocols (suggested by valid references) by the Opensees software was conducted for seismic evaluation of two regular reinforce concrete bridges. The modeling method was validated with the comparison of the analytical and experimental results under both cyclic and dynamic loading. The failure mode of the piers was considered in two-mode of flexural failure and also a flexural-shear failure. Along with the cyclic analysis, conventional analysis has been studied. Also, the nonlinear incremental dynamic analysis (IDA) method has been used to examine and compare the results of pushover analyses. The time history of 20 far-field earthquake records was used to conduct IDA. After analysis, the base shear vs. displacement in the middle of the deck was drawn. The obtained results show that the cyclic pushover analysis method is able to evaluate an accurate seismic behavior of the reinforced concrete piers of the bridges. Based on the results, the cyclic pushover has proper convergence with IDA. Its accuracy was much higher than the conventional pushover, in which the bridge piers failed in flexural-shear mode. But, in the flexural failure mode, the results of each two pushover methods were close approximately. Besides, the cyclic pushover method with ACI loading protocol, and ATC-24 loading protocol, can provided more accurate results for evaluating the seismic investigation of the bridges, specially if the bridge piers are failed in flexural-shear failure mode.