• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 2003.09a
• /
• pp.191-198
• /
• 2003

Flat slab system has been adopted in many buildings constructed recently because of the advantage of reduced floor heights to meet the economical and architectural demands. Structural engineers commonly use the equivalent frame method(EFM) with equivalent beams proposed by Jacob S. Grossman in practical engineering for the analysis of flat slab structures. However, in many cases, when it is difficult to use the EFM, it is necessary to use a refined finite element model for an accurate analysis. But it would take significant amount of computational time and memory if the entire building structure were subdivided into a finer mesh. An efficient analytical method is proposed in this study to obtain accurate results in significantly reduced computational time. The proposed method employs super elements developed using the matrix condensation technique and fictitious beams are used in the development of super elements to enforce the compatibility at the interfaces of super elements. The stiffness degradation of flat slab system considered in the EFM was taken into account by reducing the elastic modulus of floor slabs in this study. Static and dynamic analyses of example structures were peformed and the efficiency and accuracy of the proposed method were verified by comparing the results with those of the refined finite element model and the EFM.

• Structural Engineering and Mechanics
• /
• v.6 no.3
• /
• pp.305-325
• /
• 1998

A method that determines the minimum stiffness of baracing to achieve non-sway buckling conditions at a given story level of a multi-column elastic frame is proposed. Condensed equations that evaluate the required minimum stiffness of the lateral and torsional bracing are derived using the classical stability functions. The proposed method is applicable to elastic framed structures with rigid, semirigid, and simple connections. It is shown that the minimum stiffness of the bracing required by a multi-column system depends on: 1) the plan layout of the columns; 2) the variation in height and cross sectional properties among the columns; 3) the applied axial load pattern on the columns; 4) the lack of symmetry in the loading pattern, column layout, column sizes and heights that cause torsion-sway and its effects on the flexural bucking capacity; and 5) the flexural and torsional end restrains of the columns. The proposed method is limited to elastic framed structures with columns of doubly symmetrical cross section with their principal axes parallel to the global axes. However, it can be applied to inelastic structures when the nonlinear behavior is concentrated at the end connections. The effects of axial deformations in beams and columns are neglected. Three examples are presented in detail to show the effectiveness of the proposed method.

• Journal of the Korea Society for Simulation
• /
• v.30 no.3
• /
• pp.31-39
• /
• 2021

During artillery fire, an excessive level of impulse noise propagating in the form of a storm wave is generated. Since the sound of impact from the fire affects the stability of the surrounding structures, the artillery and the structures must be separated from each other by the proper distance to avoid damages from friendly fire. However, if they have already been built within the distance, it is possible to prevent the damages by building sound barriers between them. In this study, the proper separation distance between the artillery and the structure was calculated, and the insertion losses due to various heights and shapes of the sound barrier were simulated by using the BEM(Boundary Element Method), and conclusively the optimal sound barrier was selected.

• Wind and Structures
• /
• v.35 no.6
• /
• pp.385-394
• /
• 2022

The energy demand of the world is increasing rapidly, mainly using fossil energy, which causes environmental damage. The wind is free and clean energy to solve the environmental problems. Thailand is one of the developing nations, and the majority of its energy is obtained from petroleum, natural gas and coal. The objective of this study is to test the characteristics of wind energy at Khon Kaen in Thailand. The wind measurement tools, the 3-cup anemometers to measure wind speed, and wind vanes to measure wind direction, were mounted on a wind tower mast to record wind data at the heights of 60, 90 and 120 meters above ground level (AGL) for 5 years between January 2012 and December 2016. The results show that the annual mean wind speeds were 3.79, 4.32 and 4.66 m/s, respectively. The highest mean wind speeds occurred in June, August and December, in order, and the lowest occurred in September. The majority of prevailing wind directions were from the North-East and South-West directions. The average annual wind shear coefficient was 0.297. Furthermore, five wind turbines with rated power from 0.85 to 4.5 MW were selected to estimate the wind energy output and it was found that the maximum AEP and CF were achieved from the low cut-in speed and high hub-height wind turbines. This important information will help to develop wind energy applications, such as the plan to produce electricity and the calculation of the wind load that affects tall and large structures.

• Earthquakes and Structures
• /
• v.21 no.5
• /
• pp.461-475
• /
• 2021

Strategic structures are a potential target of the growing terrorist attacks, so their performance under explosion hazard has been paid attention by researchers in the last years. In this regard, the aim of this study is to evaluate the blast-resistance performance of lead-rubber bearing (LRB) base isolation system based on a probabilistic framework while uncertainties related to the charge weight and standoff distance have been taken into account. A sensitivity analysis is first performed to show the effect of explosion uncertainty on the response of base-isolated buildings. The blast fragility curve is then developed for three base-isolated steel moment-resisting buildings with different heights of 4, 8 and 12 stories. The results of sensitivity analysis show that although LRB has the capability of reducing the peak response of buildings under explosion hazard, this control system may lead to increase in the peak response of buildings under some explosion scenarios. This shows the high importance of probabilistic-based assessment of isolated structures under explosion hazard. The blast fragility analysis shows effective performance of LRB in mitigating the probability of failure of buildings. Therefore, LRB can be introduced as effective control system for the protection of buildings from explosion hazard regarding uncertainty effect.

• Structural Engineering and Mechanics
• /
• v.87 no.4
• /
• pp.347-361
• /
• 2023

This research aims to assess the behavior of reinforced concrete (RC) residential buildings when moment-resisting frames (MRFs) are used as the lateral resisting system. This investigation was conducted using MIDAS Gen v.19.0. Buildings with various plan footprints (Square, Rectangular, Circular, Triangular, and Plus-Shaped), and different heights (15 m, 30 m, 45 m, and 60 m) are investigated. The defined load cases, the equivalent static lateral load pattern, and the response spectrum function were defined as stated by the American Standard (ASCE 7-16), the 1997 Uniform Building Code (UBC97), the Egyptian Code for Loads (ECP-201), and the European Standard (EC8). Extensive comparisons of the results obtained by the different codes (including the story displacement, the story drift, and the base shear) were undertaken; to assess the response of moment-resisting multi-story framed buildings under lateral loads. The results revealed that, for all study cases under consideration, both ECP-201 and EC8 gave smaller base shear, displacement, and drift by one third to one fourth, around one fourth, around one fifth, respectively for both the ELF and RSA methods if compared to ASCE 7-16 and UBC97.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.35 no.1 s.120
• /
• pp.1-8
• /
• 2007

The purpose of this study is to suggest the minimum distance needed between landscape trees and apartment buildings. in order for the trees to grow soundly and maintain constant growth. Therefore, this study investigated and analyzed the present conditions of the green-spaces contiguous to apartment buildings and the trees inside the apartment complex. The following general problems were identified : (1) the tree growth conditions, (2) the planting intervals, and (3) the planting methods in the apartment complexes. The method of this study was to survey areas, measure the trees and analyze the results. Ten apartment complexes located in Seoul were randomly selected for this study. To analyze the greens contiguous to the building of each apartment complex, the greens were divided into three types, including the front greens, the side greens, and the rear greens. The study surveyed the width of all contiguous greens and the distance from trees to my given building. Four representative sites were specifically investigated to measure the crown widths, heights, and diameters of the trees. These investigations were carried out over 3 months from August to December 2006. According to the results of the study, it was found that the greens are narrower in width and the more closer to a building. The study identified a correlation between the tree and the passage of time after the completion of construction of an apartment complex, showing that the malformation of the trees worsened as time passed. As a result of measuring the right crown and left crown width with the tree trunk as the center, a broad difference was found between coniform trees and trees that tend to branch out more. For example, the ratio of the width of the Acer palmatum is 1:6. However, the ratio of the Metasequoia glyptostroboide is 1:1.7. Based on the overall analysis, it was concluded that the maintained minimum width must be greater than one meter over the green space according to the 'Landscape Standard 2000'. However, that is only applicable to cases such as apartment buildings that present no obstacles. In conclusion having greens placed within one meter of width to a building is not an appropriate environment for the healthy growth of trees. To create sound green spaces, sustainable, long-term growth rate and size should be considered. It is necessary to prepare new standards for the computation of planting trees and the measurement of square landscapes. Wall greenery and shrubberies could be an alternative in the case of a narrow-width green space.

• Journal of the Korean Geosynthetics Society
• /
• v.17 no.4
• /
• pp.119-128
• /
• 2018

Limit state design has been implemented in Korea since 2015; however, there exists no specification of lateral load determination on retaining wall due to the Korean standard traffic load on retaining wall's backfill surface. The lateral load from traffic depends on lane number, standard truck's axle loads and locations, loading distance from the inner wall. The concept of equivalent height of soil accounting for traffic loadings is typically used for design of retaining walls to quantify the traffic loads transmitted to the inner wall faces. Due to the different characteristics of the standard design trucks between Korea and US (AASHTO), the direct use of the guidelines from AASHTO LRFD leads to incorrect estimation of traffic load effects on retaining walls. This paper presents the results of evaluation of equivalent height of soil to reflect the Korean standard truck, based on the findings from analytical solutions using Bounessq's theory and numerical assessment using 2D finite element method. Consequently, it was found that the equivalent heights of soil from the Korean standard truck load were lower for lower retaining wall height.

• Journal of the Korea Institute of Building Construction
• /
• v.20 no.3
• /
• pp.269-278
• /
• 2020

In this study, we analyzed the safety accidents that occurred in the apartment construction site and the correlations between the victims according to the type of work accidents through multiple correspondence analysis. There is a lack of disaster-related studies on apartment construction sites, the third most frequent building type in Korea, and most of them have used survey techniques. Therefore, the exploratory data analysis was conducted in industrial accident cause data, and derived the correlation analysis between each disaster victim through multiple correspondence analysis. The results of the study are summarized in two as follows. First, as the number of heights increased due to the high rise and complexity of apartments, the fall rate and mortality rate were high. In addition, deaths are mostly caused by very few experienced workers or those with more than 10 years of experience, resulting from safety training, lack of experience, and insensitivity to safety. Second, multi-correspondence analysis showed that most safety accidents can be prevented by wearing safety equipment, and following proper work process and its safety action. The key factors derived from this study can be used for safety education, supervision, and management in apartment construction sites.

• Journal of the Korean earth science society
• /
• v.41 no.2
• /
• pp.111-128
• /
• 2020

This study presents a possibility of intensification of fine dust mass concentration due to the complex urban structure using data mining technique and clustering analysis. The data mining technique showed no significant correlation between fine dust concentration and regional-use public urban data over Seoul. However, clustering analysis based on nationwide-use public data showed that building heights (floors) have a strong correlation particularly with PM₁₀. The modeling analyses using the single canopy model and the micro-atmospheric modeling program (ENVI-Met. 4) conducted that the controlled atmospheric convection in urban area leaded to the congested flow pattern depending on the building along the distribution and height. The complex structure of urban building controls convective activity resulted in stagnation condition and fine dust increase near the surface. Consequently, the residual effect through the changes in the thermal environment caused by the shape and structure of the urban buildings must be considered in the fine dust distribution. It is notable that the atmospheric congestion may be misidentified as an important implications for providing information about the residual probability of fine dust mass concentration in the complex urban area.