عنوان مقاله [English]
Diagrids as lateral-resistant systems in tall buildings, have received much attention in recent years. Most of previous research works model the structure on rigid foundations. It is while, the soil beneath the foundation has some degree of flexibility that should be modeled. Hence, the present work take into account the static soil-structure interaction in such systems. Therefore, a vertical spring is inserted in the structural model. A finite element program is provided here for analyzing diagrid systems under a number of loading combinations considering both gravitational and lateral wind loading. As the structural behavior depends on the distribution of section profiles among its members, sizing optimization is employed for screening the diagrid designs.
In this regard, falcon optimization algorithm is concerned as a recent meta-heuristic. As FOA is based on just sampling the design space without need to any gradient calculation, it is selected and utilized for structural design. The algorithm is recently developed in 2019 and applied for heat exchanger design. It is inspired by Falcons’ hunting behavior simulated via distinct parts of their flight: 1) logarithmic spiral flight in which the falcon keeps its head straight looking sideways at the prey with maximum visual acuity, and 2) diving toward the prey by binocular vision. The first stage provides exploration while the second models search intensification in such a metaheuristic algorithm. In addition, the phenomena of klepto-parasitism between falcons is modeled to enhance the search.
In order to exactly apply both axial and flexural section properties in such a discrete problem, profile indices are taken design variables. They are to be selected from the practical list of profiles during optimization. Member grouping is also employed to deserve symmetry and practical consideration in the models.
Consequently, diagrid design is fixed minimizing the structural weight under code-based stress and deformation constraints. The designs are distinctly obtained for two cases of rigid and flexible soil-structure connections. Applying the external penalty approach, constraints are checked under simultaneous gravitational and wind loading and satisfied in the final optimal designs. Applying pushover analyses, various measures are studied and compared showing importance of soil-flexibility not only in the optimal costs but also in non-linear structural results.