# Seismic Comparison of Hybrid Steel-Reinforced Concrete and Conventional Frames
## 4 Conclusions  
In this original study, conventional r/c, steel, and hybrid steel-r/c steel buildings are designed and dimensioned according to the applicable codes [2; 3; 4; 5; 6; 7]. The hybrid and typical buildings are subjected to strong near-fault ground excitations, considering angle orientations of 0\({}^{\circ}\) and 90\({}^{\circ}\). \"Nonlinear time history analysis\" [1] is accomplished at the three series of examined frames, incorporating an appropriate mechanical model for the elastoplastic demeanor of the r/c sections of the structural members and steel ones. In addition, for the hybrid steel-r/c frames, two boundary interconnection types are examined concerning the \"fixed\" or \"fixed-pinned\" backing of the structural steel portion on the reinforced concrete part. As an initial investigation in the literature, the analysis compares earthquake reactions among the 3D hybrid frames and the typical r/c and steel frames, using the latter as a reference point. This investigation limits its findings to regular building structures with symmetrical in-plan configurations and does not consider the possible  
Figure 34: Base shear ratio “FX ratio” comparison for six-story buildings. Figure 35: Base shear ratio “FY ratio” comparison for six-story buildings. effect of ground deformability. The comparative presentation of the response results and plot used unitless factors to ensure objective findings on structural resilience, as noticed subsequently. Using hybrid building materials is cost-effective due primarily to the smaller cross-sectional dimensions of structural elements. Compared with traditional reinforced concrete (r/c) and steel buildings, hybrid models adopt less material while preserving structural integrity, which may reduce material costs and construction times. This advantage emphasizes hybrid construction's economic and practical benefits, making it an attractive choice for maximizing performance and affordability in modern building design. The findings of the 3D NLTH analysis show that hybrid buildings demonstrate greater structural resilience compared to conventional steel and reinforced concrete similar buildings. The smaller number of structural failures suggests that the hybrid building form may enhance overall safety and durability. Additionally, the increased exceedance of the inter-story drift ratio (IDR) limits in steel buildings highlights potential challenges in their design, emphasizing the need for improved lateral stiffness strategies. These results underscore the advantages of hybrid construction in mitigating structural vulnerabilities, making it a promising approach for future engineering applications. The inter-story drift ratio (IDR) distribution shows crucial structural performance features across building types. The highest IDR values in reinforced concrete (r/c) and hybrid buildings are concentrated on the first level, showing that these structures deform more near the base. In contrast, steel buildings have an increased IDR on the second floor, indicating an individual deformation profile that may need unique design approaches. Furthermore, conventional steel and r/c structures exhibit a greater IDR in the \(Y\)-axis, whereas hybrid buildings have a more balanced reaction in both horizontal directions, emphasizing their structural stability. The more significant fluctuation in the IDR for steel buildings, notably during the collapse prevention (CP) performance stage, highlights their increased susceptibility to severe deformations. These findings illustrate the importance of specialized engineering approaches to enhance steel structural resilience further and establish hybrid systems' effectiveness in minimizing excessive lateral displacement under strong earthquakes. Steel buildings have a higher dimensionless PFA/PGA ratio than the reinforced concrete (r/c) or hybrid models, with hybrid buildings showing slightly higher respective values than the r/c ones.