The effect of different soil groups on the optimum design of space steel frame structures

Nowadays, heuristic optimization methods are widely used in many areas of engineering disciplines and provide effective solutions for solving complex problems. In this study, the Dandelion Optimization Algorithm (DO), which simulates the three-stage flight behavior of a dandelion seed, is used to optimally design four different space steel frame structures for different soil classes. The structural examples used in the study are 132-element, 135-element (braced), 428-element and 720-element (10-story) space steel frames. The DO algorithm was coded using MATLAB programming language and integrated with SAP2000 software via Open Application Programming Interface (OAPI). The sizing and optimization processes of the structures were carried out based on the Turkish Building Earthquake Code (TBDY-2018) and the Principles for the Design, Calculation and Construction of Steel Structures (ÇBYHY-2016), and strength, stability and displacement constraints were taken into account in the analyses. The structures were optimized separately under five different soil classes, namely ZA, ZB, ZC, ZD and ZE as defined in TBDY-2018, and the results obtained were compared. As a result of the analyses, it was observed that the optimum cross-sectional dimensions of the structures increased as the soil class progressed from ZA to ZE and accordingly, the total weight of the structure increased significantly. In this context, 68%, 50%, 57%, 57% and 45% weight increases were observed in the 132-element model, 135-element model, 428-element model and 720-element model, respectively. Similarly, the total earthquake forces experienced by the structures increased by 258%, 468%, 292% and 160%, respectively. These results reveal that both the structural requirements and seismic demands of the structures increase significantly as the soil softens, emphasizing the critical role of soil class on structural design. This reveals that soil properties have a direct impact on structural optimization.