## 13 Smart Materials and Sensors  
Recent advancements in smart materials and sensing technologies offer promising opportunities to enhance the seismic performance of steel-concrete composite structures [189].  
Smart materials, such as shape memory alloys and magnetorheological fluids, can provide adaptive responses to seismic loads, while modern sensors enable real-time monitoring of structural behavior during earthquakes [190]. These technologies can potentially revolutionize how composite structures respond to and recover from seismic events. When integrated with traditional composite construction methods, smart materials, and sensors can facilitate more resilient structural systems, offering capabilities, such as self-centering, enhanced energy dissipation, and immediate post-earthquake damage assessment ([PERSON] et al., 2024) [191]. The implementation of these innovations represents a significant step toward developing more intelligent and responsive seismic-resistant structures.  
Current research demonstrates the potential of piezoelectric materials, fiber optic sensors, and wireless sensor networks in revolutionizing structural health monitoring for composite structures. [PERSON] et al. (2018) [192] found that these systems can detect and quantify damage in real-time, enabling prompt post-earthquake assessment and informed decision-making regarding building occupancy and required repairs. [PERSON] et al. (2020) [193] found that embedded sensors could monitor key parameters, such as strain, displacement, and acceleration, providing valuable data for both immediate safety evaluations and long-term performance analysis. The integration of these sensing technologies with machine learning algorithms further enhances their capability to predict structural behavior and identify potential vulnerabilities before they become critical ([PERSON], 2015) [194].  
[PERSON] et al. (2018) [195] examined the internal concrete damage in L-shaped concrete-filled steel tube (L-CFST) columns using piezo-ceramic smart aggregates under low-frequency cyclic loading. Wavelet packet analysis established the damage index. Experimental results showed the feasibility of using smart aggregates to monitor concrete damage in L-CFST columns.  
[PERSON] et al. (2021) [196] found that the practical implementation of smart materials in composite structures has shown promising results in experimental studies. [PERSON] et al. (2015) [197] reviewed a variety of smart materials' connection details to concrete-filled rectangular tubular (CFRT) columns that different researchers have developed. Shape memory alloys incorporated into beam-column connections have demonstrated superior energy dissipation and self-centering capabilities compared to conventional solutions. Thus, [PERSON] et al. (2018) [198] and [PERSON] (2023) [199] examined the application of self-centering principles on steel-concrete composite structures, where they found that the self-centering composite frames have reduced permanent deformations while the initial posttensioned forces can control their uplifting force.  
Magnetorheological dampers have been successfully employed to provide adaptive damping in response to varying seismic intensities. However, challenges remain in scaling these technologies for widespread application, including cost considerations, long-term durability, and the need for standardized design guidelines [200]. Addressing these obstacles requires collaborative efforts between researchers, practitioners, and regulatory bodies to develop comprehensive frameworks for the effective integration of smart technologies into composite structural systems [201].