철골 트러스 구조의 자동화 최적설계

편해완,김용주,김수원,강문명 한국공간구조학회 2001 한국공간구조학회지 Vol.1 No.1

Generally, truss design has been determined by the designer's experience and intuition. But if we perform the most economical structural design we must consider not only cross-sections of members but also configurations(howe, warren and pratt types etc.) of single truss as the number of panel and truss height. The purpose of this study is to develope automated optimum design techniques for steel truss structures considering cross-sections of members and shape of trusses simultaneously. As the results, it could be possible to find easily the optimum solutions subject to design conditions at the preliminary structural design stage of the steel truss structures. In this study, the objective function is expressed as the whole member weight of trusses, and the applied constraints are as stresses, slenderness ratio, local buckling, deflection, member cross-sectional dimensions and truss height etc. The automated optimum design algorithm of this study is divided into three-level procedures. The first level on member cross-sectional optimization is performed by the sequential unconstrained minimization technique(SUMT) using dynamic programming method. And the second level about truss height optimization is applied for obtaining the optimum truss height by three-equal interval search method. The last level of optimization is applied for obtaining the optimum panel number of truss by integer programming method. The algorithm of multi-level optimization programming technique proposed in this study is more helpful for the economical design of plane trusses as well as space trusses.

Rehabilitation of a distressed steel roof truss - A study

M.A. Dar,N. Subramanian,A.R. Dar,J. Raju 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.62 No.5

Structural failures are undesirable events that devastate the construction industry resulting in loss of life, injury, huge property loss, and also affect the economy of the region. Roof truss failures occur mainly due to excessive loading, improper fabrication, deterioration, inadequate repair, etc. Although very rare, a roof truss may even fail due to inappropriate location of supports. One such case was reported from the recent failure of a steel roof truss used in an indoor stadium at Kargil in India. Kargil region, being mountainous in nature, receives heavy snowfall and hence the steel roof trusses are designed for heavy snow loads. Due to inappropriate support location, the indoor stadium’s steel roof truss had failed under heavy snow load for which it was designed and became an interesting structural engineering problem. The failure observed was primarily in terms of yielding of the bottom chord under the supports, leading to partial collapse of the roof truss. This paper summarizes the results of laboratory tests and analytical studies that focused on the validation of the proposed remedial measure for rehabilitating this distressed steel roof truss. The study presents the evaluation of (i) significant reduction in strength and stiffness of the distressed truss resulting in its failure, (ii) desired recovery in both strength and stiffness of the rectified truss contributed by the proposed remedial measure. Three types of models i.e., ideal truss model, as build truss model and rectified truss model were fabricated and tested under monotonic loading. The structural configuration and support condition varied in all the three models to represent the ideal truss, distressed truss and the rectified truss. To verify the accuracy of the experimental results, an analytical study was carried out and the results of this analytical study are compared with the experimental ones.

근대건축문화재의 목조지붕트러스에 관한 연구

박창범,김태영 대한건축학회지회연합회 2008 대한건축학회지회연합회 학술발표대회논문집 Vol.2008 No.1

This paper is aimed to clarify the characteristics of wooden roof trusses in modern age of Korea. These western roof trusses are largely classified with king post roof truss, queen post roof truss, and so on. The king and queen post roof truss are respectively classified with 3 types by the roof span. The king post roof trusses are composed with the principal rafter, tie beam, strut, braces, purlins, and so on. They are spanning up to about 4.5-8m, 9-12m, 12.5-16.2m, each of them has 6, 4, 2 struts and lattice members But there are practically no 6 struts and lattice members in the king post roof truss of wooden architectural properties. The queen post roof truss enable the construction of the very large roof trusses than the king post roof trusses, the knee brace are when bay is more than 5m between the queen posts. An further innovation was the use of iron tie bars in lieu of timber for tensile lattice members(struts) in the trusses.

Cost minimization of prestressed steel trusses considering shape and size variables

Zekeriya Aydın,Ebru Cakir 국제구조공학회 2015 Steel and Composite Structures, An International J Vol.19 No.1

There are many studies on the optimization of steel trusses in literature; and, a large number of them include a shape optimization. However, only a few of these studies are focused on the prestressed steel trusses. Therefore, this paper aims to determine the amounts of the material and cost savings in steel plane trusses in the case of prestressing. A parallel-chord simply supported steel truss is handled as an example to evaluate the used approach. It is considered that prestressing tendon is settled under the bottom bar, between two end supports, using deviators. Cross-sections of the truss members and height of the truss are taken as the design variables. The prestress losses are calculated in two steps as instantaneous losses and time-dependent losses. Tension increment in prestressing tendon due to the external loads is also considered. A computer program based on genetic algorithm is developed to solve the optimization problem. The handled truss is optimized for different span lengths and different tendon eccentricities using the coded program. The effects of span length and eccentricity of tendon on prestressed truss optimization are investigated. The results of different solutions are compared with each other and those of the non-prestressed solution. It is concluded that the amounts of the material and the cost of a steel plane truss can be reduced up to 19.9% and 14.6%, respectively, by applying prestressing.

A Numerical Study to Evaluate the Changes in Dynamic Properties of Various Steel Truss Types Under Fire Conditions

R. Sibil,E. Ozyurt 한국강구조학회 2023 International Journal of Steel Structures Vol.23 No.6

This study numerically examines the changes in dynamic properties of fire-damaged steel trusses made of square hollow sections subjected to uniform and non-uniform heating scenarios. After verifying the numerical models at both ambient and elevated temperatures, a vast number of the simulations were analysed using non-linear finite element software to evaluate the effects of fire scenarios, truss types, and fire-damaged levels on the fire dynamic characteristics of square hollow section Warren, Howe, and Pratt trusses. The results indicated that the natural frequency of steel trusses significantly decreased as the fire-damaged level increased. In the case of local fire, the natural frequencies of the trusses began to drop suddenly at temperatures above 550 °C. Whereas the drop in the natural frequency of the uniformly heated trusses started at even much lower temperature levels. Moreover, the decrease in the natural fundamental frequencies of the uniformly heated trusses was lower than the reduction rate of the modulus of elasticity at high temperatures due to the large non-linear deformations. Since the modification of the stiffness of the truss by simply the reduction factor of the elastic modulus of the steel may be inappropriate to calculate the fundamental frequency of the trusses in the local and global fires, a new method was introduced to calculate the fundamental frequency value of the steel trusses in the fire.

Research on a New Class of Planar Tensegrity Trusses Consisting of Repetitive Units

Sili Li,Xian Xu,Jiaqi Tu,Yafeng Wang,Yao-Zhi Luo 한국강구조학회 2020 International Journal of Steel Structures Vol.20 No.5

Tensegrity structure is a prestressed self-equilibrated system consisting of compressed struts and tensioned cables. Planar truss is one of the most common forms of engineering structures with a wide application. This paper proposes a new class of planar tensegrity trusses whose prototype is unintentionally found by a topology optimization algorithm. The prototype truss is composed of two basic units which are combined alternately. In this paper, the state of prestress of the truss is analytically determined from the equilibrium conditions. The stiff ness and strength of the structure are analytically formulated by using the principle of virtual work. Parametric analysis of geometrical parameters on the stiff ness and strength of the structure is carried out. By changing the shape of the basic units, the uniform planar tensegrity truss is extended to a fi sh-bellied truss. Parametric analysis is also carried out for the fi sh-bellied truss. An example of extending the planar tensegrity truss into a three-dimensional latticed tensegrity truss is also given.

사재 형식별 트러스 구조물의 안전성 평가 연구

송영봉(Song Young Bong),채원규(Chai Won Kyu) 한국지적정보학회 2008 한국지적정보학회지 Vol.10 No.1

본 연구에서는 사재 형식에 따른 트러스 구조물의 안전성을 검토하였다. 이를 위해 트러스 구조물의 종류별 부재력과 절점 변위의 변화를 알아보기 위하여 하우트러스, 와렌트러스, 프래트트러스에 대하여 각각 구조해석을 수행하였다. 구조해석 결과 절점하중 재하시 수직재의 부재력은 하우트러스에서 크게 나타났으며, 상현재의 부재력은 와렌트러스의 중앙부 부재에서 가장 크게 나타남을 알 수 있었다. 또한 온도하중 재하 시 상현재의 수직방향 변형률은 와렌트러스의 중앙부 부재에서 가장 크게 나타남을 알 수 있었다. In this thesis, the structural analysis was performed on the truss structures to investigate the member forces and the joint displacements of the truss structures. The howe truss, the warren truss, and the pratt truss are used in the structural analysis. From the structural analysis results, the maximum member force of the upper chord member was occurred in the warren truss, and that of the vertical member was occurred in the howe truss. According to the deformation diagrams by the temperature load, it was found that the maximum deformations were occurred in the warren truss structure.

방울토마토의 적엽이 수량과 품질에 미치는 영향

박한영,도명자 建國大學校附設 農業資源開發硏究所 1998 農資源開發論集 Vol.20 No.-

Abstract Six different defoliation patterns were applied to investigate the effect of defoliation on the yield and characteristics of fruit of cherry tomato, 'Mini Carol'. Total fruit yield was maximized in the treatment in which all the lower leaves were defoliated except for the first four leaves under 3rd flower truss. Total fruit yield decreased with increasing defoliation rate, resulting in the least flower truss were defoliated. However, truss from 2nd to 5th flower except for 1st flower truss showed a similar pattern in yield. With respect to fruit's characteristics, the height, diameter, soluble solids concentration, and maturity of fruit were most desirable when 2∼4 leaves under the 3rd flower truss were left and all the below leaves were defoliated. The data suggested that the most appropriate defoliation method for cherry tomato cultivation appeared to be when all the below leaves were defoliated except for 2∼4 leaves under the 3rd flower truss, on the basis of evaluation of yield, height, diameter, soluble solids concentration, and maturity. Six different defoliation patterns were applied to investigate the effect of defoliation on the yield and characteristics of fruit of cherry tomato, 'Mini Carol', Total fruit yield was maximized in the treatment in which al1 the lower leaves were defoliated except for the first four loaves under 3rd flower truss. Total fruit yield decreased with increasing defoliation rate, resulting in the least flower truss were defoliated. However, truss from 2nd to 5th flower except for 1st flower truss showed a similar pattern in yield. With respect to fruit's characteristics, the height, diameter, soluble solids concentration, and maturity of fruit were most desirable when 2~4 leaves under the 3rd flower truss were left and all the below leaves were defoliated. The data suggested that the most appropriate defoliation method for cherry tomato cultivation appeared to be when all the below leaves were defoliated except for 2~4 leaves under the 3rd flower truss, on the basis of evaluation of yield, height, diameter, soluble solids concentration, and maturity.

근대기 목조 지붕트러스의 부재 크기에 관한 연구

정훈철,권순찬,김태영 대한건축학회지회연합회 2011 대한건축학회연합논문집 Vol.13 No.4

근대기 목조 지붕트러스 55건 중 왕대공트러스 35건, 쌍대공트러스 20건을 대상으로, 각각의 부재들에 대하여 근대기 기술서상에서 나타난 부재의 크기와 기록화 조사보고서를 통해 조사된 부재의 크기를 비교, 분석한 결과 다음과 같은 특징이 나타났다. 왕대공 지붕트러스의 부재 크기인 폭과 높이에 있어서, 人자보와 평보는 1920년 이전 「(화양)건축설계제도」의 치수인 150☓210㎜와 150☓240㎜를 따르고, 이후 부재의 폭이 감소하면서 「양식건축구조추형」의 치수인 120☓150㎜와 120☓240㎜를 따르고 있다. 왕대공에서는 1940년대를 전후하여 이전에는 「(화양)건축설계제도」와 「양식건축구조추형」의 치수인 120☓120㎜와 150☓150㎜의 정방형 각재를 따르고, 이후에는 부재의 폭이 감소하면서 부재 치수 120☓180㎜ 전후의 직사각형 각재가 사용되었다. 빗대공과 달대공은 1940년 이전 왕대공과 유사하거나 작게 나타나고, 이후 「건축구조학」에서 제시하는 부재 크기인 60∼90☓120㎜로 유사하게 나타났다. 쌍대공 지붕트러스의 부재 크기는 왕대공 지붕트러스와 같이 시기적인 특징을 보이지 않고 용도에 따라 업무시설의 人자보, 평보, 쌍대공은 「(화양)건축설계제도」의 치수인 180☓210㎜와 180☓300㎜, 180☓180㎜를 따르고, 교육시설의 人자보, 평보, 쌍대공은 「양식건축구조추형」의 치수인 120☓210㎜, 120☓240㎜, 120☓180㎜를 따라 나타난다. 버팀대공, 빗대공, 달대공의 부재 크기는 다른 트러스의 주요부재와는 달리 보조하는 부재로서 주요부재에서 나타난 경향과 다르게 나타났고 주로 정방형에 가까운 각재가 사용되었다. The purpose of this study is to find out changes and characteristics on sizes of members on wooden roof trusses of Modern Architectural Properties. The types of wooden roof trusses in this times are generally classified into king post truss and queen post truss. The sizes of the principal rafter and tie beam of the king post roof truss are 150⨯210㎜ and 150⨯240㎜ each by the book "Western Architectural Design and Drafting(和洋建築設計製圖)" until 1920. The sizes of the principal rafter and tie beam of the king post roof truss are 120⨯150㎜ and 120⨯240㎜ each by the book "Early Pattern of Construction in Western Architectural Style(洋式建築構造雛形)" after 1920. The size of the king post is 120⨯120㎜ by the book "Early Pattern of Construction in Western Architectural Style" and 150⨯150㎜ by the book "Western Architectural Design and Drafting" before 1940. The size of the king post is 120⨯180㎜ afterwards. The member size of the queen post roof truss did not show a periodic feature like the king post roof truss. The sizes of the principal rafter, tie beam, and queen post are 180⨯210㎜, 180⨯300㎜, and 180⨯180㎜ each in office facilities by the book "Western Architectural Design and Drafting". The sizes of the principal rafter, tie beam, and queen post are 120⨯210㎜, 120⨯240㎜, and 120⨯180㎜ each in educational facilities by the book "Early Pattern of Construction in Western Architectural Style".

근대기 목조 지붕트러스의 유형분류 및 특징에 관한 연구

박창범(Park Chang-Beom),김미연(Kim Mi-Yeon),김태영(Kim Tai-Young) 대한건축학회 2008 대한건축학회논문집 Vol.24 No.8

This paper is aimed to clarify the type and its characteristics of wooden roof truss in modern age of Korea focused 64 architectural properties. These are largely classified with traditional korean and japanese roof structure, western king and queen post roof truss, and so on. The roof structure of korean architecture have been evolved into combining traditional wooden structure(rafter) with wooden roof truss. Korean carpenters have tried to improve wood structure by using the principal rafter, bracing, and tie beam, and had continually efforts to receive the roof style of west. The king and queen post roof truss are respectively classified with 3 types by the roof span. The king post roof trusses are composed with the principal rafter, tie beam, strut, braces, purlins, and so on. They are spanning up to about 4.5-8m, 9-12m, 12.5-16.2m, each of them has 6, 4, 2 struts and lattice members But there are practically no 6 struts and lattice members in the king post roof truss of wooden architectural properties. The queen post roof trusses enable the construction of the very large span than the king post roof trusses, the knee brace are used when bay is more than 5m between the queen posts. An further innovation was the use of iron tie bars in lieu of timber for tensile lattice members in the trusses.