• Steel and Composite Structures
• /
• v.45 no.4
• /
• pp.579-590
• /
• 2022

One of the biggest problems in structural steel calculation is the design of structures using the lowest possible material weight, making this a slow and costly process. To achieve this objective, several optimization methods have been developed and tested. Nevertheless, a method that performs very efficiently when applied to different problems is not yet available. Based on this assumption, this work proposes a hybrid metaheuristic algorithm for geometric and dimensional optimization of space trusses, called Simulated Squirrel Search Algorithm, which consists of an association of the well-established neighborhood shifting algorithm (Simulated Annealing) with a recently developed promising population algorithm (Squirrel Search Algorithm, or SSA). In this study, two models are tried, being respectively, a classical model from the literature (25-bar space truss) and a roof system composed of space trusses. The structures are subjected to resistance and displacement constraints. A penalty function using Fuzzy Logic (FL) is investigated. Comparative analyses are performed between the Squirrel Search Algorithm (SSSA) and other optimization methods present in the literature. The results obtained indicate that the proposed method can be competitive with other heuristics.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.11 no.2
• /
• pp.93-102
• /
• 2007

A large number of FRP decks are already in service worldwide because the lighter FRP-based bridge decks are ideal for rapid construction to reduce the dead load of superstructures. And the proper design process is demanded for the effective FRP deck application. In this paper, to get the basic prototype of FRP bridge decks, the ratio of individual parameters, which compose the specification of FRP bridge decks, are determined by a finite element analysis. In addition, optimum FRP deck shapes are determined considering complex constraints and material properties of bi-directional characteristics. Upon these results, the prototype of FRP bridge decks is validated.

• Journal of Mechanical Science and Technology
• /
• v.18 no.9
• /
• pp.1512-1518
• /
• 2004

Rescaled Simulated Annealing (RSA) has been adapted to solve combinatorial optimization problems in which the available computational resources are limited. Simulated Annealing (SA) is one of the most popular combinatorial optimization algorithms because of its convenience of use and because of the good asymptotic results of convergence to optimal solutions. However, SA is too slow to converge in many problems. RSA was introduced by extending the Metropolis procedure in SA. The extension rescales the state's energy candidate for a transition before applying the Metropolis criterion. The rescaling process accelerates convergence to the optimal solutions by reducing transitions from high energy local minima. In this paper, structural optimization examples using RSA are provided. Truss structures of which design variables are discrete or continuous are optimized with stress and displacement constraints. The optimization results by RSA are compared with the results from classical SA. The comparison shows that the numbers of optimization iterations can be effectively reduced using RSA.

• Journal of Ocean Engineering and Technology
• /
• v.17 no.6
• /
• pp.53-57
• /
• 2003

Optimum design of most structural system requires that design variables are regarded as discrete quantities. This paper presents the use of Genetic Algorithm for determining the optimum design for truss with discrete variables. Genetic Algorithm are know as heuristic search algorithms, and are effective global search methods for discrete optimization. In this paper, Elitism and the method of conferring penalty parameters in the design variables, in order to achieve improved fitness in the reproduction process, is used in the Genetic Algorithm. A 10-Bar plane truss and a 25-Bar space truss are used for discrete optimization. These structures are designed for stress and displacement constraints, but buckling is not considered. In particular, we obtain continuous solution using Genetic Algorithms for a 10-bar truss, compared with other results. The effectiveness of Genetic Algorithms for global optimization is demonstrated through two truss examples.

• Korean Journal of Computational Design and Engineering
• /
• v.13 no.6
• /
• pp.412-420
• /
• 2008

In order to design the large complex structures like VLFS (Very Large Floating Structures), it is essential the cooperation between the experts in various fields; structural engineering expert, fluid mechanics expert, mooring system engineer, and so on. This paper describes the development of an integrated system to support the cooperative design between various experts and project manager. This integrated system is designed to be operated in Web environment and it contains the support of design DB and 3D graphical tool, negotiation tool for task allocation, and various engineering supporting tools for each design step. The user group of this system can be classified as Project Manager, Engineering Expert, DB Builder, and System Administrator. All of the engineering data is saved after and during the process of the design projects and all participants can be connected by Internet without the limit of time or space constraints.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2003.04a
• /
• pp.176-179
• /
• 2003

This paper deals with the optimum design of thick-walled multi-layered composite tubes by minimizing the process-induced residual stresses under some constraints of structural stiffnesses. An analytic model based on quasi-static thermoelasticity is adopted for the calculation of the residual stresses in the multi-layered composite tubes. The numerical results of optimization show that, in the case of cross-ply CFRP tubes, the residual stresses can be reduced to a certain level by controlling ply thicknesses. However, the optimized tubes may be susceptible to cracking because the transverse residual stress is still large in a strength-based sense. To further suppress the residual stresses, the effects of stacking sequence, wall thickness and axial pretension on the optimum solutions are examined.

• Proceedings of the Korea Institute of Convergence Signal Processing
• /
• 2001.06a
• /
• pp.69-72
• /
• 2001

High-level synthesis generates a structural design that implements the given behavior and satisfies design constraints for area, performance, power consumption, packaging, testing and other criteria. Thus, high-level synthesis generates that register-transfer(RT) level structure from algorithm level description. High-level syntehsis consist of compiling, partitioning, scheduling This paper we study the partitioning process, and analysis the min-cut algorithm and simulated annealing algorithm.

• Structural Engineering and Mechanics
• /
• v.33 no.3
• /
• pp.285-306
• /
• 2009

In the literature the problem of the topology optimization of the structure is usually solved for one, clearly described from the mechanical point of view material. Generally the topology optimization answers the question of the distribution of this mentioned above material within the design domain. Finally, material-voids distribution it is obtained. In this paper, for the structure mainly strengthened or sometimes weakened by the inclusions, the variation approach of the topology optimization problem is formulated. This multi material approach may be useful for the design process of various mechanical or civil engineering structures which need to be more "refined" and more "optimal" than they can be using previous topology optimization procedures of optimization one material structures.

• Journal of Korean Association for Spatial Structures
• /
• v.21 no.1
• /
• pp.61-70
• /
• 2021

This paper describes a novel zero-stress member selecting method for sizing optimization of truss structures. When a sizing optimization method with static constraints is implemented, the member stresses are affected sensitively with changing the variables. However, because some truss members are unaffected by specific loading cases, zero-stress states are experienced by the elements. The zero-stress members could affect the computational cost and time of sizing optimization processes. Feature selection approaches can be then used to eliminate the zero-stress member from the whole variables prior to the process of optimization. Several numerical truss examples are tested using the proposed methods.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.24 no.5
• /
• pp.543-551
• /
• 2011

The paper deals with the comparative study of design optimization based on various approximation techniques in strength design of riser support structure installed on floating production storage and offloading unit(FPSO) using offshore operation loading conditions. The design optimization problem is formulated such that structural member sizing variables are determined by minimizing the weight of riser support structure subject to the constraints of structural strength in terms of loading conditions. The approximation techniques used in the comparative study are response surface method based sequential approximate optimization(RBSAO), Kriging based sequential approximate optimization(KBSAO), and the enhanced moving least squares method(MLSM) based approximate optimization such as CF(constraint feasible)-MLSM and Post-MLSM. Commercial process integration and design optimization(PIDO) tools are employed for the applications of RBSAO and KBSAO. The enhanced MLSM based approximate optimization techniques are newly developed to ensure the constraint feasibility. In the context of numerical performances such as design solution and computational cost, the solution results from approximate techniques based design optimization are compared to actual non-approximate design optimization.