• Title/Summary/Keyword: wall-frame

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Seismic Performance of Precast Infill Walls with Strain-Hardening Cementitious Composites (변형경화형 시멘트 복합체를 사용한 프리캐스트 끼움벽의 내진성능)

  • Kim, Sun-Woo;Yun, Hyun-Do;Jang, Gwang-Soo;Yun, Yeo-Jin
    • Journal of the Korea Concrete Institute
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    • v.21 no.3
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    • pp.327-335
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    • 2009
  • In the seismic region, non-ductile structures often form soft story and exhibit brittle collapse. However, structure demolition and new structure construction strategies have serious problems, as construction waste, environmental pollution and popular complain. And these methods can be uneconomical. Therefore, to satisfy seismic performance, so many seismic retrofit methods have been investigated. There are some retrofit methods as infill walls, steel brace, continuous walls, buttress, wing walls, jacketing of column or beam. Among them, the infilled frames exhibit complex behavior as follows: flexible frames experiment large deflection and rotations at the joints, and infilled shear walls fail mainly in shear at relatively small displacements. Therefore, the combined action of the composite system differs significantly from that of the frame or wall alone. Purpose of research is evaluation on the seismic performance of infill walls, and improvement concept of this paper is use of SHCCs (strain-hardening cementitious composites) to absorb damage energy effectively. The experimental investigation consisted of cyclic loading tests on 1/3-scale models of infill walls. The experimental results, as expected, show that the multiple crack pattern, strength, and energy dissipation capacity are superior for SHCC infill wall due to bridging of fibers and stress redistribution in cement matrix.

A Study on the Generation of Ultrasonic Binary Image for Image Segmentation (Image segmentation을 위한 초음파 이진 영상 생성에 관한 연구)

  • Choe, Heung-Ho;Yuk, In-Su
    • Journal of Biomedical Engineering Research
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    • v.19 no.6
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    • pp.571-575
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    • 1998
  • One of the most significant features of diagnostic ultrasonic instruments is to provide real time information of the soft tissues movements. Echocardiogram has been widely used for diagnosis of heart diseases since it is able to show real time images of heart valves and walls. However, the currently used ultrasonic images are deteriorated due to presence of speckle noises and image dropout. Therefore, it is very important to develop a new technique which can enhance ultrasonic images. In this study, a technique which extracts enhanced binary images in echocardiograms was proposed. For this purpose, a digital moving image file was made from analog echocardiogram, then it was stored as 8-bit gray-level for each frame. For an efficient image processing, the region containing the heat septum and tricuspid valve was selected as the region of interest(ROI). Image enhancement filters and morphology filters were used to reduce speckle noises in the images. The proposed procedure in this paper resulted in binary images with enhanced contour compared to those form the conventional threshold technique and original image processing technique which can be further implemented for the quantitative analysis of the left ventricular wall motion in echocardiogram by easy detection of the heart wall contours.

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Development of A Prototype for Wall Formwork Designs using Open BIM (개방형 BIM을 활용한 벽체 거푸집설계 프로토타입 개발)

  • Jin, Chengquan;Kim, Hyunjoo;Hyun, Chang-Taek;Han, Sang-Won
    • Korean Journal of Construction Engineering and Management
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    • v.19 no.6
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    • pp.3-13
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    • 2018
  • The formwork cost amounts for a significant proportion of project construction costs. It costs 10-15% of the total construction cost and 30-40% of the frame structure construction cost. In addition, the formwork collapse accidents are frequently causing deaths in the construction industry, and thus, is known to be of relatively high degree of risk. As so, the accuracy of structural calculation and quantity take-off when planning the formwork in a construction project are a very important matter. Accordingly, this study develops a BIM based formwork design prototype, that enables the construction manager to optimize the design through applying the proposed new IFC entities associated with the formwork design. The approach proposed in this study is expected to support the construction manager with accurate quantity calculation and rapid planning and construction. Since this study considered specific small-scale buildings using Euro-form and show the possibility of utilizing BIM entities in the formwork design process, further research is recommended towards the limitations in applying the system to other types of formworks.

Effect of Aspect Ratio and Diagonal Reinforcement on Shear Performance of Concrete Coupling Beams Reinforced with High-Strength Steel Bars (세장비 및 대각철근 유무에 따른 고강도 철근보강 콘크리트 연결보의 전단성능)

  • Kim, Sun-Woo;Jang, Seok-Joon;Yun, Hyun-Do;Seo, Soo-Yeon;Chun, Young-Soo
    • Journal of the Korea Concrete Institute
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    • v.29 no.1
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    • pp.43-51
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    • 2017
  • As per current seismic design codes, diagonally reinforced coupling beams are restricted to coupling beams having aspect ratio below 4. However, a grouped diagonally reinforcement detail makes distribution of steel bars in the beam much harder, furthermore it may result in poor construction quality. This paper describes the experimental results of concrete coupling beam reinforced with high-strength steel bars (SD500 & SD600 grades). In order to improve workability for fabricating coupling beams, a headed large diameter steel bar was used in this study. Two full-scale coupling beams were fabricated and tested with variables of reinforcement details and aspect ratio. To reflect real behavior characteristic of the beam coupling shear walls, a rigid steel frame system with linked joints was set on the reaction floor. As a test result, it was noted that cracking and yielding of reinforcement were initially progressed at the coupling beam-to-shear wall joint, and were progressed to the mid-span of the coupling beam, based on the steel strain and failure modes. It was found that the coupling beams have sufficient deformation capacity for drift ratio of shear wall corresponding to the design displacement in FEMA 450-1. In this study, the headed horizontal steel bar was also efficient for coupling beams to exhibit shear performance required by seismic design codes. For detailed design for coupling beam reinforced with high-strength steel, however, research about the effect of variable aspect ratios on the structural behavior of coupling beam is suggested.

Analyzing the Design Competition Entries for the Hoehyeon Section of Namsan from a Perspective of the Historic Urban Landscape (남산 회현자락 설계 공모 출품작에 대한 역사도시경관적 분석)

  • Seo, Young-Ai
    • Journal of the Korean Institute of Landscape Architecture
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    • v.43 no.4
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    • pp.27-36
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    • 2015
  • This study analyzed the characteristics of the entries at the design competition for the Hoehyeon section of Namsan from a perspective of the Historic Urban Landscape and made suggestions from them. Hoehyeon, located at the foot of Namsan, is the most changing site in the park and Seoul City Wall. Recent excavation of the old city walls of the Joseon Era has uncovered evidence of the Japanese occupation period, making it a site where park facilities in modern and contemporary history coexist. The frame analysis has been made by the concept of the Historic Urban Landscape, the methods of approach, specialists' discussion and the guidelines of the competition. The entries were analyzed by classification of the understanding of the spatiality and cultural diversity, the recognition of the periodic layers of time, and the design implementation, the preservation, the park plan, and the future management plan. From a perspective of an Historic Urban Landscape, this study has found that each entry placed priority on the objects for preservation and suggested creative involvement and comprehensive designs for the preservation and the park plan through the understanding of the spatiality and cultural diversity and the reflection of the periodic layers of time in the designs. This study provided two implications. Firstly, there was a possibility for new recognition and the methods of approach for preservation and development. Secondly, the basic plan for the Historic Landscape should be established through research and mapping for the preservation and management of objects in Seoul having valuable historic variability. Further study for resident participation and the process by network from public to private should be taken. This study looks forward to the consideration of the direction for the design plans of places with historic and cultural value.

A Study on the Pan-Jang in the Joseon Dynasty (조선시대 판장(板墻)에 관한 연구)

  • Oh, Jun-young;Kim, Young-mo
    • Korean Journal of Heritage: History & Science
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    • v.49 no.1
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    • pp.68-83
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    • 2016
  • Pan-jang(板墻) has become the lost facility, and the examples of its original form can be found no more due to its variable material characteristics. In order to study panjang as a lost facility, the following are needed: - To bring to light its usage and examples. - To investigate its components and structure. Panjang refers to the wall made of wooden plate and is classified as a special wall according to its material characteristics. In addition, Chinese mokyeongbyuk(木影壁) and Japanese panbyeong(板?) are similar to Korean panjang in terms of the materials, but there are clear differences in their structures. Panjang was also transformed into various types according to their materials or forms. As the wooden elements of panjang, sinbang(信防), pillars, do-ri(道里), jungbang(中枋), inbang(引枋), parn(板), dae(帶), choyeop(草葉), bangyeon(方椽), gaeparn(蓋板), pyeonggodae(平高臺), and yeonharm(椽檻) were selectively used, and they are similar, in particular, to the components of ilgakmoon(一角門). The stylobate of panjang is largely classified into three according to the kinds and structures of the wooden elements; and its frame into two according to whether sanginbang(上引枋) is used or not. The materials for the roof area include planks(蓋板) and tiles and have the distinct structural differences according to each material.

The Characteristics of Traditional Representation in the Artist's Garden of the Garden Exposition seen through the Design Process (설계과정을 통해 본 정원박람회 작가정원의 전통재현 특성)

  • Lee, Song-Min;So, Hyun-Su
    • Journal of the Korean Institute of Traditional Landscape Architecture
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    • v.38 no.4
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    • pp.101-110
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    • 2020
  • This study was conducted through the analysis of literature and on-site research as a case study of 14 artists' gardens with traditional themes presented at the garden fair. With Focusing on the design process for determining traditional reproduction, the following characteristics and implications were derived by analyzing the design goals, selection of subjects for traditional reenactment, determination of methods for reproduction, and design stages of landscape components. First, the pattern of selecting traditional structures as subjects for reproduction in many artist gardens can be understood as an advantage of being suitable for narrow sites and having remarkable topic communicability. They directly delivered the design intent by adding the names of traditional structures such as Madang, Wool, Buttumak, Jangdokdae, Chuibyeong and Seokgasan. Works expressed indirectly, such as Wall, Korean Garden, Suwon, and Seoul craftsmen, have relatively weak topic communicability. There were also symbolic representations of objects to be reproduced, such as Seonbi, marginal spaces, and Pung-lyu. Second, while reproducing Hanok Madang, separate the gardens paved with grass and stone, the fortress wall of Suwon Hwaseong and the northwest Gongsimdon of the watchtower. Also the garden with a miniature version of the extraneous Yong-yeon and the garden, which was reproduced as a low decorative wall in the rest area based on Nakan-Eupseong Fortress, shows the need for a deep understanding of tradition. On the other hand, the reproducting works of choosing the location of the traditional garden, the Korean Garden showed the importance of systematic arrangement with the surrounding environment, the beauty of the space in the courtyard of Hanok, the beauty of the slowness enjoyed by the scholars and the reenactments of the Pung-lyu culture of Moonlight boating are not only imitating traditional structures but also spreading understanding of tradition to garden culture and sentiment. Third, there were many works that reconstructed the real-size traditional structure in a straightforward way in relation to design. The garden was divided into Chuibyeong and the living space was decorated with Buttumak, chimneys, and gardens, and facilities representing Gyeongbokgung Palace, Soswaewon, and Seoseokji were systemically arranged. However it recognized the importance of selecting the key design elements, constructing the elevation of the structure, and the sense of scale of the space from works that reproduced the large Suwon Hwaseong and Nakan-Eupseong in an abstract way. While there are examples gardens of Hanok yards and Bazawul, which are far from the original image among the gardens that chose the dismantling method, the Blank-space garden expressed only by a frame composed of cubes, and Seonbi's Sarangbang garden, that permeated the moonlight with many traditional structures are the positive examples. The Seoul Artisan Garden, Jikji Simche Garden and Pung-lyu Garden, which display modernly designed landscape components, need an explanation to understand the author's intention.

Development of the Drift Design Method of High-rise Buildings using Weight Control Factors (중량 조절계수를 이용한 고층 건물 변위설계법 개발)

  • Park, Hyo Seon;Seo, Ji Hyun
    • Journal of Korean Society of Steel Construction
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    • v.17 no.3 s.76
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    • pp.285-294
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    • 2005
  • Drift design is one of the core techniques in the structural design of high-rise buildings and resizing technique is regarded as a practical drift design method for high-rise buildings. In the resizing technique, the structural weight is re-distributed to minimize the target displacement without a change in structural weights. However, the structural weight determined from resizing algorithm is bound to the structural weight based on the preliminary design. Therefore, in this paper, a drift design method that can control the weight of the structure without causing drift control performance to deteriorate is proposed by incorporating the weight control factor in the formulation of resizing algorithm. The proposed drift design method is applied to the drift design of two frame-shear wall systems. The proposed drift design method, in this study, makes it possible to control both the drift and weight of a high-rise building.

The Nonlinear Direct Spectrum Method Improving Application and Reliability of Existing Approximate Nonlinear Methods (기존 비선형약산법들의 신뢰성 개선을 위한 비선형직접스펙트럼법)

  • Kim, Jae-Ung;Kang, Pyeong-Doo;Jun, Dae-Han
    • Journal of the Earthquake Engineering Society of Korea
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    • v.10 no.4 s.50
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    • pp.55-66
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    • 2006
  • This paper considers the nonlinear direct spectrum method to estimate seismic performance of mixed building structures without iterative computations, given dynamic property $T_1$ from stiffness skeleton curve and nonlinear pseudo acceleration $A_{1y}/g$ and/or ductility ratio p from response spectrum. Nonlinear response history analysis has been performed and analysed with various earthquakes for evaluation of correctness and confidence of nonlinear direct spectrum method. The conclusions of this study are as follows; (1) Nonlinear direct spectrum method is considered as a practical method which is applicable to compute the structural initial elastic period and the yielding strength from stiffness skeleton owe and calculate the nonlinear maximum response of structure directly from nonlinear response spectrum. (2) The comparison of the analysis results from NDSM and NRHA showed that the average errors were less than 20% in about 3/4 of the analysis cases, and that the results obtained from NDSM turned out to be generally larger than those from NRHA.

A correlation between moisture and compressive strength of a damaged 15-year-old rammed soil house

  • Preciado, Adolfo;Santos, Juan Carlos;Ramirez-Gaytan, Alejandro;Ayala, Karla;Garcia, Jose de Jesus
    • Geomechanics and Engineering
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    • v.23 no.3
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    • pp.227-244
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    • 2020
  • Earthen structures have an excellent bioclimatic performance, but they are vulnerable against earthquakes. In order to investigate the edification process and costs, a full-scale rammed soil house was constructed in 2004. In 2016-2019, it was studied its seismic damage, durability and degradation process. During 2004-2016, the house presented a relatively good seismic performance (Mw=5.6-6.4). The damaged cover contributed in the fast deterioration of walls. In 2018 it was observed a partial collapse of one wall due to recent seismicity (Mw=5.6-6.1). The 15-year-old samples presented a reduced compressive strength (0.040 MPa) and a minimum moisture (1.38%). It is estimated that the existing house has approximately a remaining 20% of compressive strength with a degradation of about 5.4% (0.0109 MPa) per year (considering a time frame of 15 years) if compared to the new soil samples (0.2028 MPa, 3.52% of moisture). This correlation between moisture and compressive strength degradation was compared with the study of new soil samples at the same construction site and compared against the extracted samples from the 15-year-old house. At 7-14-days, the specimens presented a similar compressive strength as the degraded ones, but different moisture. Conversely, the 60-days specimens shown almost five times more strength as the existing samples for a similar moisture. It was observed in new rammed soil that the lower the water content, the higher the compressive/shear strength.