• 한국해양공학회지
• /
• 제27권5호
• /
• pp.36-42
• /
• 2013

We present the optimum design for the cross-sectional(sizing) and shape optimization of truss structures with natural frequency constraints. The optimum design method used in this paper employs continuous design variables and the Harmony Search Algorithm(HSA). HSA is a meta-heuristic search method for global optimization problems. In this paper, HSA uses the method of random number selection in an update process, along with penalty parameters, to construct the initial harmony memory in order to improve the fitness in the initial and update processes. In examples, 10-bar and 72-bar trusses are optimized for sizing, and 37-bar bridge type truss and 52-bar(like dome) for sizing and shape. Four typical truss optimization examples are employed to demonstrate the availability of HSA for finding the minimum weight optimum truss with multiple natural frequency constraints.

• 한국강구조학회 논문집
• /
• 제22권2호
• /
• pp.197-208
• /
• 2010

언더텐션이란 상부에서의 하중을 하부 케이블의 인장력을 이용하여 그 하중을 양 단부로 전달하는 시스템을 말하며 처짐과 부재 크기를 제어하기 위해 장스팬 구조물에 주로 적용된다. 하지만 수많은 단면 중에서 여러 조건을 만족하며 최소의 물량, 즉 최대의 경제성에 부합하는 최적의 단면을 찾는 것은 매우 어려운 일이다. 이에 본 연구에서는 마이크로 유전알고리즘을 이용하여 언더텐션 형태의 트러스 구조물에 단면 최적화 연구를 수행하였으며 처짐과 허용응력 그리고 좌굴이 제약조건으로 고려되었다. 최적화 검증 예제로 자주 사용되는 10-bar 트러스 예제의 이전 연구 결과와의 비교를 통하여 개발된 프로그램을 검증하였다. 이를 바탕으로 프리텐션 크기를 변수로 설정하여 언더텐션 구조물의 최적 설계를 수행하였다. 본 연구에서 제시된 최적설계 그래프를 통하여 설계자가 일정 조건을 만족하는 최적의 단면을 쉽게 선택할 수 있을 것으로 사료된다.

• Steel and Composite Structures
• /
• 제44권5호
• /
• pp.603-617
• /
• 2022

Structural design, in general, is developed through trial and error technique which is guided by standards criteria and based on the intuition and experience of the engineer, a context that leads to structural over-dimensioning, with uneconomic solutions. Aiming to find the optimal design, structural optimization methods have been developed to find a balance between cost, structural safety, and material performance. These methods have become a great opportunity in the steel structural engineering domain since they have as their main purpose is weight minimization, a factor directly correlated to the real cost of the structure. Assuming an objective function of minimum weight with stress and displacement constraints provided by Brazilian standards, the present research proposes the sizing optimization and combined approach of sizing and shape optimization, through a software developed to implement the Simulated Annealing metaheuristic algorithm. Therefore, two steel plane frame layouts, each admitting four typical truss geometries, were proposed in order to expose the difference between the optimal solutions. The assessment of the optimal solutions indicates a notable weight reduction, especially in sizing and shape optimization combination, in which the quantity of design variables is increased along with the search space, improving the efficiency of the optimal solutions achieved.

• 한국강구조학회 논문집
• /
• 제10권3호통권36호
• /
• pp.487-495
• /
• 1998

스페이스 프레임 구조물은 내부 기둥이 없는 대공간을 덮을 수 있다는 장점 때문에 현재의 많은 구조가와 설계자들에게 큰 관심을 받고 있다. 본 연구에서 다루는 강성구조 이산화시스템인 스페이스 트러스는 기하학적 비선형항이 포함된 대변형 이론을 이용한 유한요소법을 응력해석 방법으로 사용하며, 비선형최적화에 적합한 GINO(General Interactive Nonlinear Optimizer) 프로그램을 이용하여 구조물에 대한 전체체적을 목적함수로 하고 부재의 축력강도, 세장비, 처짐 및 국부좌굴 등으로 제약조건식을 유도하여 최적 설계를 하고자 한다.

• 한국공간구조학회논문집
• /
• 제21권3호
• /
• pp.77-84
• /
• 2021

In this study, In order to apply the U-flanged truss hybrid beam to the actual construction site, the structural design of the basic module of the middle and low-rise neighborhood living facilities was performed according to the Korea Design Standard, and the construction cost and construction period were compared with the traditional reinforced concrete structure system. As a result of analyzing the construction cost for the basic module, if the U-flanged truss hybrid beam and D-Deck slab system are used, the construction cost can be reduced by 86% compared to the traditional reinforced concrete structure system. In addition, as a result of analyzing the construction period for a floor area of 1,000m², using the U-flanged truss hybrid beam and D-Deck slab system can save 2.0days in construction period compared to the traditional reinforced concrete structure system. Therefore, the U-flange truss hybrid beam can secure sufficient economic feasibility compared to the existing reinforced concrete method in terms of cost reduction and shortening of construction period.

• Smart Structures and Systems
• /
• 제21권6호
• /
• pp.715-725
• /
• 2018

Truss-Z (TZ) is an Extremely Modular System (EMS). Such systems allow for creation of structurally sound free-form structures, are comprised of as few types of modules as possible, and are not constrained by a regular tessellation of space. Their objective is to create spatial structures in given environments connecting given terminals without self-intersections and obstacle-intersections. TZ is a skeletal modular system for creating free-form pedestrian ramps and ramp networks. The previous research on TZ focused on global discrete geometric optimization of the spatial configuration of modules. This paper reports on the first attempts at structural optimization of the module for a single-branch TZ. The internal topology and the sizing of module beams are subject to optimization. An important challenge is that the module is to be universal: it must be designed for the worst case scenario, as defined by the module position within a TZ branch and the geometric configuration of the branch itself. There are four variations of each module, and the number of unique TZ configurations grows exponentially with the branch length. The aim is to obtain minimum-mass modules with the von Mises equivalent stress constrained under certain design load. The resulting modules are further evaluated also in terms of the typical structural criterion of compliance.

• Steel and Composite Structures
• /
• 제6권2호
• /
• pp.103-122
• /
• 2006

The capacity of tubular truss chords subjected to concentrated reaction forces in the vicinity of the open end (i.e., the bearing region) is not directly treated by existing design specifications; although capacity equations are promulgated for related tubular joint configurations. The lack of direct treatment of bearing capacity in existing design specifications seems to represent an unsatisfactory situation given the fact that connections very often control the design of long-span tubular structures comprised of members with slender cross-sections. The case of the simple-span overhead highway sign truss is studied, in which the bearing reaction is applied near the chord end. The present research is aimed at assessing the validity of adapting existing specifications' capacity equations from related cases so as to be applicable in determining design capacity in tubular truss bearing regions. These modified capacity equations are subsequently used in comparisons with full-scale experimental results obtained from testing carried out at the University of Pittsburgh.

• 비파괴검사학회지
• /
• 제28권2호
• /
• pp.217-224
• /
• 2008

트러스는 교량이나 건축물 설계 등에 많이 사용되는 구조물로서 기본적인 설계요소이며, 설계자는 이러한 구조물의 원리를 완전히 이해하여 설계에 적용할 수 있어야 한다. 본 논문에서는 트러스 구조물의 힘을 기본역학에서 예측되는 오차범위 이내로 실험법으로 측정할 수 있는 기구설계 방법을 제시하였다. 상용으로 제작된 재래식 변형률 측정 장치는 고가이고 복잡하므로 구조를 이해하기가 어려우므로 본 측정기구에서는 휘트스톤브리지 회로를 적용, 스트레인 게이지 및 A/D 변환기 조립하여 하중과 변형률을 쉽게 측정할 수 있도록 하였다. 제작된 기구를 이용하여 구조물에 하중을 가하여 변형률을 측정하였으며, 측정결과를 이론적으로 예측한 값과 비교하여 실용성을 입증하였다. 이 측정 기구는 저렴한 값으로 제작할 수 있으며, 크기가 작아 탁상에서 교육용 실험 및 실습 장비로 적합할 것으로 사료된다.

• Architectural research
• /
• 제4권1호
• /
• pp.33-38
• /
• 2002

The objective of this study is the development of discrete optimum design algorithms which is based on the genetic algorithms. The developed algorithms was implemented in a computer program. For the optimum design, the objective function is the weight of space trusses structures and the constraints are stresses and displacements. This study solves the problem by introducing the genetic algorithms. The genetic algorithms consists of genetic process and evolutionary process. The genetic process selects the next design points based on the survivability of the current design points. The evolutionary process evaluates the survivability of the design points selected from the genetic process. The efficiency and validity of the developed discrete optimum design algorithms was verified by applying the algorithms to optimum design examples.

• Steel and Composite Structures
• /
• 제20권6호
• /
• pp.1237-1257
• /
• 2016

The paper concerns analysis of effects of shrinkage of slab concrete in a steel-concrete composite deck of a through truss bridge span. Attention is paid to the shrinkage alongside the span, i.e., transverse to steel-concrete composite cross-beams. So far this aspect has not been given much attention in spite of the fact that it affects not only steel-concrete decks of bridges but also steel-concrete floors of steel frame building structures. For the problem analysis a two-dimensional model is created. An analytical method is presented in detail. A set of linear equations is built to compute axial forces in members of truss girder flange and transverse shear forces in steel-concrete composite beams. Finally a case study is shown: test loading of twin railway truss bridge spans is described, verified FEM model of the spans is presented and computational results of FEM and the analytical method are compared. Conclusions concerning applicability of the presented analytical method to practical design are drawn. The presented analytical method provides satisfactory accuracy of results in comparison with the verified FEM model.