بهينه سازي سطح مقطع و ارتفاع شبكه هاي دولايه

Optimization of Depth and Cross-Section of Double-Layer Grids

Double layer grids are typical examples of prefabricated space structures and also one of the most popular forms of space frames .Since nowadays many double layer grids are constructed all over the world, optimization of their design has a great influence on decreasing the costs and used materials. Some techniques have been developed by Salajegheh et al. for cross-section optimization of double layer grids. In this research an attempt has been made to include a geometrical parameter in optimization process. To that end a two-phase method is presented. In the first phase of optimization the cross-section areas are optimized using optimality criteria method (OC) for different layer dimensions. In the second phase, quadratic interpolation method is used to optimize the depth of the structure. This new depth is replaced for one of the previous depths and the two-phase optimization process is repeated until convergence is achieved. Four examples with different topologies but the same loading and boundary conditions have been solved; this algorithm prepares the ground for the comparison of costs of different topologies and selection of optimal topology as well. For the solved example, the optimum topology among these topologies is determined.