Optimization of structural and mechanical engineering problems using the enriched ViS-BLAST method

Babak Dizangian,Mohammad Reza Ghasemi 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.77 No.5

In this paper, an enhanced Violation-based Sensitivity analysis and Border-Line Adaptive Sliding Technique (ViS-BLAST) will be utilized for optimization of some well-known structural and mechanical engineering problems. ViS-BLAST has already been introduced by the authors for solving truss optimization problems. For those problems, this method showed a satisfactory enactment both in speed and efficiency. The Enriched ViS-BLAST or EVB is introduced to be vastly applicable to any solvable constrained optimization problem without any specific initialization. It uses one-directional step-wise searching technique and mostly limits exploration to the vicinity of FNF border and does not explore the entire design space. It first enters the feasible region very quickly and keeps the feasibility of solutions. For doing this important, EVB groups variables for specifying the desired searching directions in order to moving toward best solutions out or inside feasible domains. EVB was employed for solving seven numerical engineering design problems. Results show that for problems with tiny or even complex feasible regions with a larger number of highly non-linear constraints, EVB has a better performance compared to some records in the literature. This dominance was evaluated in terms of the feasibility of solutions, the quality of optimum objective values found and the total number of function evaluations performed.

An efficient method for reliable optimum design of trusses

Babak Dizangian,Mohammad Reza Ghasemi 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.21 No.5

This paper introduces a new and effective design amplification factor-based approach for reliable optimum design of trusses. This paper may be categorized as in the family of decoupled methods that aiming for a reliable optimum design based on a Design Amplification Factor (DAF). To reduce the computational expenses of reliability analysis, an improved version of Response Surface Method (RSM) was used. Having applied this approach to two planar and one spatial truss problems, it exhibited a satisfactory performance.This paper introduces a new and effective design amplification factor-based approach for reliable optimum design of trusses. This paper may be categorized as in the family of decoupled methods that aiming for a reliable optimum design based on a Design Amplification Factor (DAF). To reduce the computational expenses of reliability analysis, an improved version of Response Surface Method (RSM) was used. Having applied this approach to two planar and one spatial truss problems, it exhibited a satisfactory performance.

Practical optimization of power transmission towers using the RBF-based ABC algorithm

Faezeh Taheri,Mohammad Reza Ghasemi,Babak Dizangian 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.73 No.4

This paper is aimed to address a simultaneous optimization of the size, shape, and topology of steel lattice towers through a combination of the radial basis function (RBF) neural networks and the artificial bee colony (ABC) metaheuristic algorithm to reduce the computational time because mere metaheuristic optimization algorithms require much time for calculations. To verify the results, use has been made of the CIGRÉ Tower and a 132 kV transmission towers as numerical examples both based on the design requirements of the ASCE10-97, and the size, shape, and topology have been optimized (in both cases) once by the RBF neural network and once by the MSTOWER analyzer. A comparison of the results shows that the neural network-based method has been able to yield acceptable results through much less computational time.

Enhancing seismic performance of ductile moment frames with delayed wire-rope bracing using middle steel plate

Akram Ghalandari,Mohammad Reza Ghasemi,Babak Dizangian 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.28 No.2

Moment frames have considerable ductility against cyclic lateral loads and displacements; however, sometimes this feature causes the relative displacement to exceed the permissible limits. This issue can bring unfavorable hysteretic behavior on the frame due to the reduction in the stiffness and resistance against lateral loads. Most of common bracing systems usually control lateral displacements through increasing stiffness while result in decreasing the capacity for energy absorption. This has direct effect on hysteresis curves of moment frames. Therefore, a system that is capable of both having the capacity of energy absorption as well as controlling the displacements without a considerable increase in the stiffness is quite important. This paper investigates retrofitting of a single-storey steel moment frame using a delayed wire-rope bracing system equipped with the ductile middle steel plate. The steel plate is considered at the middle intersection of wire ropes, where it causes cables to be continuously in tension. This integrated system has the advantage of reducing considerable stiffness of the frame compared to cross bracing systems as a result of which it could also preserve the frame's energy absorption capacity. In this paper, FEM models of a delayed wire-rope bracing system equipped by steel plates with different geometries have been studied, validated, and compared with other researchers' laboratory test results.

A fast damage detecting technique for indeterminate trusses

Arash Naderi,Mohammad Reza Sohrabi,Mohammad Reza Ghasemi,Babak Dizangian 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.75 No.5

Detecting the damage of indeterminate trusses is of major importance in the literature. This paper proposes a quick approach in this regard, utilizing a precise mathematical approach based on Finite Element Method. Different to a general two-step method defined in the literature essentially based on optimization approach, this method consists of three steps including Damage-Suspected Element Identification step, Imminent Damaged Element Identification step, and finally, Damage Severity Detection step and does not need any optimizing algorithm. The first step focuses on the identification of damage-suspected elements using an index based on modal residual force vector. In the second step, imminent damage elements are identified among the damage-suspected elements detected in the previous step using a specific technique. Ultimately, in the third step, a novel relation is derived to calculate the damage severity of each imminent damaged element. To show the efficiency and quick function of the proposed method, three examples including a 25-bar planar truss, a 31-bar planar truss, and a 52-bar space truss are studied; results of which indicate that the method is innovatively capable of suitably detecting, for indeterminate trusses, not only damaged elements but also their individual damage severity by carrying out solely one analysis.

Total and Partial Updating Technique: A Swift Approach for Cross-Section and Geometry Optimization of Truss Structures

Arash Naderi,Mohammad Reza Sohrabi,Mohammad Reza Ghasemi,Babak Dizangian 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.4

In this paper, a novel two-phase method called Total and Partial Updating Technique, is employed for the cross section and geometry optimization of truss structures. The goal of optimizing such structures is to minimize their weights under natural frequency constraints. In Total and Partial Updating Technique, in order to find the global optimum point, only the best two existed solution points at each repetition move together in the search space defined in each phase. Each time, the first phase is destined to find a solution near the global optimum point although searching in the unfeasible region. In the second phase, it is forced jumping into the feasible region to reach the global optimum point. The comparison of the results with those in the literature on two numerical examples demonstrates that due to its relatively significant low computational costs and its assured non-violated constrained optimum solutions at the end of the process, the method may be considered as more reliable and efficient technique on such problems.