## 8 Composite Construction and Foundation Seismic Design  
### Composite Construction and Foundation Seismic Design: State-of-the-Art  
Seismic design of foundations for steel-concrete composite buildings is crucial for ensuring safety during earthquakes. The process involves analyzing the dynamic response of the structure, considering factors, like frequency and resonance. Deep foundations, like piles or caissions, may be used to transfer loads to stable soil layers. Measures, like base isolation and energy dissipation devices, help mitigate ground motion effects. The stiffness and strength of the foundation are important for overall seismic performance. Design codes and standards provide guidelines, emphasizing capacity design principles to ensure plastic deformations occur in predetermined locations. Overall, a comprehensive understanding of soil-structure interaction, material behavior, and dynamic analysis techniques is necessary for creating resilient structures that can withstand seismic events. [PERSON] et al. (2021) [129] developed two column-to-foundation connections for square CFT columns. Experimental and numerical assessments were conducted, comparing the connections with existing ones for their inelastic deformation capacity when subjected to cyclic loading. The results demonstrate the efficient and improved behavior of the suggested connections, with the numerical models accurately predicting the experimental response. Similarly, [PERSON] et al. (2020) [130] introduced two new and efficient connections for connecting concrete-filled steel tube (CFST) columns to reinforced concrete foundations. The connections were designed to withstand seismic loading and were tested against conventional CFT and reinforced concrete column-to-foundation connections. The results showed that the proposed connections performed better. Finite element models accurately predicted the behavior of these connections, as confirmed by the experimental results. [PERSON] et al. (2021) [131] examined the use of concrete-filled steel tube piles in deep foundation systems under seismic and cyclic loads. They found that composite piles effectively mitigate damage in hard-to-reach areas, such as the pile heads and deep depths. Controlled loading analyses and seismic-intensity analysis confirmed the capacity margins of the composite pile system. They also discussed the damage patterns, displacement profiles, and residual displacement of composite piles compared to concrete piles. The results showed that composite piles exhibited 40% less damage on average than reinforced concrete piles. Moreover, [PERSON] et al. (2015) [132] examined the mechanical properties of reinforced concrete and steel-concrete composite members under seismic loads, specifically in the context of elevated pile-group foundations used in bridge and ocean engineering. Four scale-specimens were created and tested, comparing their seismic performance. The results showed that the composite specimens had higher peak strength, higher ultimate displacement, and higher energy dissipation capability than the reinforced concrete specimens. [PERSON] et al. (2020) [133] focused on steel-plate composite walls and their connections to foundations. Eight large-scale specimens were tested to examine the behavior of composite wall-to-foundation connections under axial compression and cyclic lateral force. The specimens were tested in different loading directions and using different connection construction details and aspect ratios. The results showed that the lap splice connection was stronger, while the embedding connection allowed for more ductility. The current expressions for load-carrying capacities were found to be underestimated. Similarly, [PERSON] et al. (2022) [134] demonstrated how a baseplate and eccentric anchors could be used to attach steel-plate composite walls to a concrete basemat.