Multi-objective morphology optimization of free-form cable-braced grid shells

Abstract

This paper examines the multi-objective morphology optimization of free-form cable-braced grid shells. First, according to the shape forming method for grid shells, shape optimization can be realized by adjusting the generatrix and directrix rather than optimizing the whole surface. Second, the multi-objective shape optimization of free-form cable-braced grid shells is conducted. According to different practical requirements, the mechanical and geometric indexes, mechanical and economic indexes, or different mechanical indexes are used as multiple optimization objectives. Four main conclusions can be drawn from this study. First, with the above shape optimization method, the optimized surface does not change significantly; therefore, this method is useful in the shape optimization of grid shells with given initial surfaces. Second, among the static mechanical performance indexes, the mechanical behavior of the cable-braced grid shell is better with strain energy as the optimization objective. Third, with the weight of steel tubes and strain energy as the optimization objectives, the result of the multi-objective optimization that combines section optimization with shape optimization is favorable and practical in engineering applications. Fourth, when strain energy and the variance of the tube lengths are used as multiple optimization objectives, the structural mechanical behavior is not sensitive to the weight factor of variance of the tube lengths.