## 7 Seismic Performance of Composite Building Structures  
### Seismic Performance of Composite Buildings: State-of-the-Art  
Considering that steel-concrete composites combine the advantages of both materials and improve seismic resistance, they are common in earthquake-prone areas. These structures consist of steel frames with concrete slabs, composite columns, or composite shear walls. The interaction between steel and concrete components enhances the overall response of the structure. Steel elements provide ductility and energy dissipation capacity, while concrete components enhance stiffness and mass distribution. Composite structures also have higher strength-to-weight ratios. Various factors, like connection design, stiffness and mass distribution, and composite systems, influence seismic performance. Challenges include predicting behavior and considering bonds, concrete cracking, and nonlinear material behavior. Ongoing research aims to optimize seismic performance and create resilient structures. A displacement/damage-controlled seismic design approach for composite frames--consisting of composite beams and steel tube columns filled with concrete--was created by [PERSON] et al. (2021) [PERSON] et al. (2021) [PERSON] et al. (2021) [PERSON] et al. (2021). This method directly controls displacement and damage for all seismic performance levels, even near collapse. Empirical expressions were used to estimate the inter-story drift ratio and evaluate the damage index of critical members. By analyzing a large response databank, the necessary expressions were derived. The displacement/damage-controlled method reduced design iterations and eliminated the need for nonlinear time-history analysis. Design examples showed that the method successfully estimated inter-story drift ratio and controlled the damage index, resulting in an improved seismic performance procedure. Thus, Figure 7 shows the response (IDRs, inter-story drift ratios) of a 10-story composite building, using incremental dynamic analysis. Furthermore, [PERSON] et al. (2017) [PERSON] et al. (2021) [PERSON] et al. (2021) created a computational process to ascertain how circular steel tube columns filled with concrete would react to constant loading. Experiments were used to validate the creation of precise 3D nonlinear finite element models. A total of 192 CFT specimens with varying diameter-to-thickness ratios, steel tube yield stress, compressive strength of the concrete core, and axial load levels were subjected to a parametric investigation. Empirical expressions were derived from the study to estimate force-displacement behavior. Then, these expressions were applied for the assessment of the seismic performance of composite buildings, examining their behavior through nonlinear time-history analysis. The material models for steel and concrete examined by [PERSON] et al. (2017) [PERSON] et al. (2021) [PERSON] et al. (2021) are shown in Figure 7.  
[PERSON] et al. (2022) [PERSON] et al. (2021) [PERSON] et al. (2021) examined the impact of strong earthquakes on high-rise steel moment-resisting frames and concrete-filled tubular column frames. Over-design ground motions from large earthquakes can cause severe damage to structural components. The study used synthetic earthquake waves to assess the collapse criteria and deterioration margins of 40-story steel and composite building structures. The results showed that steel building experience collapse mechanisms in lower stories during very rare earthquakes, while the composite frames have a higher margin against overall collapse. Additionally, the behavior of steel-reinforced concrete structures prestressed by bonding tendons was investigated by [PERSON] et al. (2023) [PERSON] et al. (2023) [PERSON] et al. (2023). Fifteen groups of specimens were designed with various parameters. Finite element models were created using ABAQUS software ([https://www.3 ds.com/products/simulia/abaqus](https://www.3 ds.com/products/simulia/abaqus)) to analyze the structures un der axial forces and horizontal loads.