## 7 Seismic Performance of Composite Building Structures
### Seismic Performance of Composite Buildings: Key Findings  
Examining the seismic performance of steel-concrete composite buildings, these structures appear to have, in comparison with steel or reinforced concrete structures, enhanced ductility, increased stiffness, improved strength, enhanced damping characteristics, effective load transfer, reduced structural weight, enhanced performance of beam-column joints, beneficial composite floor systems, and the importance of proper detailing. Composite buildings exhibit improved energy dissipation, reduced lateral deflections, higher strength capacity, superior damping properties, efficient load transfer, lighter structures, improved behavior under cyclic loading, and effective distribution of lateral loads. Proper detailing, especially in critical areas, is crucial for the seismic performance of these buildings. The development of comprehensive performance-based design approaches for steel-concrete composite structures in seismic zones represents a critical challenge at the intersection of structural engineering, materials science, and advanced computational modeling. The complexity stems from the multifaceted nature of composite systems, which exhibit intricate material interactions and nonlinear behavioral characteristics under seismic loading conditions. Traditional design methodologies have predominantly relied on prescriptive approaches that often fail to capture the nuanced response of composite structural elements to dynamic loading scenarios [114]. The fundamental limitation of current design frameworks lies in their inability to fully incorporate the inherent variability of material performance and structural response across different seismic intensities and loading configurations. Composite structures present unique challenges due to the differential mechanical properties of steel and concrete, including their distinct elastic moduli, thermal expansion coefficients, and strain compatibility characteristics. These differences generate complex stress transfer mechanisms that are not adequately addressed by conventional linear elastic analysis methods ([PERSON] et al., 2022) [22]. Advanced numerical modeling techniques have emerged as a promising avenue for developing more sophisticated performance-based design approaches. Finite element analysis and multi-scale modeling techniques enable more precise characterization of the nonlinear behavior of composite structural elements. These computational methods allow for more sophisticated predictions of local and global structural responses, including the complex interactions between steel and concrete components under cyclic loading conditions [115]. The integration of machine learning algorithms with advanced numerical modeling has further expanded the potential for developing more adaptive and context-specific design methodologies. Developing performance-based design guidelines requires a comprehensive understanding of the dynamic response characteristics of composite structures across various scales. This necessitates a holistic approach integrating experimental investigations, advanced numerical modeling, and probabilistic risk assessment techniques. Researchers have increasingly focused on developing hybrid modeling approaches that combine experimental data with sophisticated computational methods to generate robust predictive frameworks ([PERSON] and [PERSON], 2023) [116]. These approaches aim to bridge the existing knowledge gaps in understanding the complex behavior of composite structures under seismic loading. One of the most significant challenges in developing performance-based design approaches is the characterization of higher mode effects and torsional responses in composite structural systems. Traditional design methodologies often simplify these complex dynamic interactions, potentially leading to significant discrepancies between predicted and actual structural performance.