Performance-based design optimization using uniform deformation theory: a comparison study

Abstract

The uniform deformation theory (UDT) is a relatively new concept in structural seismic design optimization. However, the results of optimization based on this theory have not yet been compared with other optimization techniques such as metaheuristics, and the optimality of the designs has been proved only by comparing the results with the conventional designs. This paper presents a new algorithm based on the UDT to performance-based design optimization (PBDO) of steel moment frames. In order to verify robustness of this method, the achieved results of PBDO for two baseline steel moment frames are compared with three metaheuristics consisting of genetic algorithm (GA), ant colony optimization (ACO), and particle swarm optimization (PSO). The results indicate that the optimization based on UDT provides a much higher convergence rate to the optimum design compared with metaheuristics.

An efficient discrete optimization algorithm for performance-based design optimization of steel frames

“…In this article, the deformation information, including the seismic deformation demands and the deformation capacities of structural elements, is effectively utilized to update the design variables. This is similar to UDT (Mohammadi and Ghasemof, 2015), but in UDT only Area was updated, which means that for a certain section, the search for a better design is conducted in a one-dimensional space. But when Area and Ix are considered, the search is performed in a two-dimensional space and the searching direction becomes undetermined.…”

“…Since the number of nonlinear time history analysis is mainly determined by the number of iteration, so the computational time needed by these two algorithms is comparatively small. Considering the fact that at least thousands of structural evaluations are required by metaheuristics to solve PBDO of steel frames (Gholizadeh, 2015; Gholizadeh and Moghadas, 2014; Mohammadi and Ghasemof, 2015), a high computational efficiency can be achieved by the proposed algorithm and the area-only algorithm.…”

“…And a fast convergence rate could be observed. When UDT was applied to PBDO of steel frames (Mohammadi and Ghasemof, 2015), the merit of fast convergence was preserved but the results obtained by UDT were less satisfying, compared with results obtained by some metaheuristic algorithms. When UDT was originally proposed, this method concerned more on a uniform state of inter-story deformation of shear building.…”

“…As metaheuristic algorithms have no specific requirements on the characteristics of the optimization problems, they are widely applied in various problems, including PBDO of steel frames. But the convergence rate of metaheuristic algorithms is usually very slow and at least thousands of structural analysis are needed (Gholizadeh and Ebadijalal, 2018; Mohammadi and Ghasemof, 2015; Rezazadeh et al, 2018; Talatahari, 2013) before metaheuristic algorithms can converge to a satisfying solution. This shortcoming becomes intolerable when nonlinear time history analysis is required in evaluating the structural seismic responses.…”

“…But when UDT was applied to steel frames, it became harder to reach a uniform state of deformation for columns and beams because the performance of steel frames is not controlled only by the deformation of elements. Other constraints like force-controlled constraints of elements and inter-story drift ratio constraints should also be considered (FEMA-450, 2006), which makes UDT less applicable (Mohammadi and Ghasemof, 2015). Yet, although a state of uniform deformation in structural elements can hardly be realized for seismic design of steel frames, the computational merit of UDT should be absorbed by other seismic optimization methods.…”