INTERNATIONAL JOURNAL OF SCIENTIFIC & TECHNOLOGY RESEARCH VOLUME 9, ISSUE 03, MARCH 2020 ISSN 2277-8616 160 IJSTR©2020 www.ijstr.org State-Of-The-Art Review On The Use Of Optimization Algorithms In Steel Truss Swabarna Roy, Chinmay Kumar Kundu Abstract: Structural design optimization is a mathematical approach that concerns in finding the maxima and minima function subject to some constraints. This involves various optimization technique to find the best possible design in terms of weight, reliability and thus the overall cost. Various researchers have worked on different optimization techniques in finding out the efficient and light weight structures that are essential for the actual design of tall structures. This paper summarizes the various techniques of optimization of steel truss or towers that have been used till now. For this purpose, different optimization techniques have been studied which involves the various geometric constraints like changing the base width, bracing pattern, area of cross section. By reviewing the literature of the works done, the common objective emphasizes the need for finding the minimum weight of the structure. From studies we see optimization using metaheuristic algorithm are effective in order to solve truss problems. Metaheuristic algorithms are nature -inspired and most widely used due to its applicability and feasibility to various types of structures with many numbers of design variables. In this paper a 25-bar space benchmark truss has been considered for demonstrating the performance of various optimization algorithm. A comparative study is done based on the performance in lowering the weight of the total truss. Results shows that optimal weight of the truss structure can be obtained effectively using Whale optimization algorithm and it proved to be robust and efficient than other algorithms. Index Terms: Steel truss; Metaheuristic algorithm; Optimum weight; review ———————————————————— 1 INTRODUCTION In most engineering designs, civil engineers are engaged in designing buildings, dams, bridges, and different other structures in order to accomplish a minimum overall cost or maximum safety or both [1]. For this common design objective, structural optimization has emerged. The design process in optimization of structure as announced in 80’s [2]. Optimization is a method of obtaining the best suitable result under a given circumstances. The main purpose is to obtain minimum or maximum value of the objective function [3,4]. Sometimes, optimization problem may have multiple objective functions. Structural optimization problems are of three different types. The first is the dimensional optimization which consider the sizing of the elements as design variables, which can continuously change or can be chosen from a list of available cross-sectional dimensions. The second is geometric optimization, taking into consideration the nodal coordinates. Finally, the topology optimization includes the number of elements. The minimization of cost or weight is the main objective to be achieved, and the constraints are associated with the design codes and requirements. The use of optimization algorithm has become popular recently as it deals exclusively with the mathematical form of the problem interfaced with computer model representing the physical structure. In this paper sizing optimization of space truss aimed at minimizing the weight of the structure is done under certain behavioral constraints on stress and displacements. In this paper, a 25-bar design example is considered to demonstrate the application of the optimization algorithms in determining the optimum weight of the total truss. A comparative study is done based on the performance of various algorithms in minimizing weight. 2 OPTIMIZATION TECHNIQUES Optimization process involves four different stages: formulation of function as per requirement, conceptual design stage, optimization stage and detailing. The use of algorithm in the iterative stage was before the final solution is achieved. The optimization problem has the following characteristics: a) Objective function: It is a function, associated with the dimension of the analyzed problem, which will measure the performance of the system. For example: In a two-bar truss with a load P, as shown in Figure 1, the objective function is minimization of its mass, can be written as w = ρ i .l i .a i , where ρ i is the specific mass of the system, l i is the length of the element, a i is the cross- sectional area of each member i. Fig.1. Truss example b) Design variables: they are parameters allowed to be modified to improve the objective function. They are written as vector x = (x 1 …x n ), where, n is the number of variables and E is the associated design space. For the above truss example, value of the design variables can be the value of the cross-sectional area of each member a i . The vector x can be expressed as x= (a 1 , a 2 ). c) design space: these are constraints which are applied to limit the design space and subspace S of E. In the truss, to limit the values of cross- sectional areas between the minimum and maximum __________________________________________ • Swabarna Roy is currently pursuing Ph. D in Structural engineering in KIIT Deemed to be University, Bhubaneswar, India. E-mail: swabarnaroy0210@gmail.com • Chinmay Kumar Kundu is currently working as Associate Professor in civil engineering in KIIT Deemed to be University, Bhubaneswar, India. E-mail: chinmay.kundufce@kiit.ac.in