## 6 Behavior of Composite Beam-Columns Under Cyclic Loads
### Behavior of Composite Beam-Columns Under Cyclic Loads: State-of-the-Art
Through seismic performance tests, it was observed that the steel angles improved flexural strength and stiffness, while the transverse plates reduced spalling and increased deformation capacity. The results aligned with existing models' predictions. Moreover, a concrete-filled steel tubular column and a metamaterial concrete-filled steel tubular column using rubber, lead, steel, and high load-bearing capacity concrete were designed by [PERSON] et al. (2024) [88] for vibration mitigation. The flexural bandgap theoretical model based on PWEM and a Timoshenko beam was established and analyzed. Shaking table tests confirmed its effectiveness in reducing vibrations, making it a potential solution for protecting structures from earthquakes and low-frequency lateral vibrations. [PERSON] and [PERSON] (2021) [89] recognized that, due to a lack of data, the seismic behavior of steel-reinforced-concrete composite columns having non-seismic details in older buildings is poorly understood. Furthermore, the influence of axial loads on the deformation capacity of steel-reinforced-concrete composite columns is uncertain, and there are no formal guidelines for modeling parameters or acceptance criteria for columns with modern seismic details. For these reasons, they addressed these gaps through experimental and analytical methods, examining these composite columns under cyclic loads. The test results indicate that tension-controlled steel-reinforced-concrete composite columns with non  
Figure 6: Advanced finite element modeling techniques for concrete-filled tube (CFT) columns, visualizing complex material interaction and structural response (adapted from [PERSON] et al. (2014) [84]). seismic details meet the seismic assessment criteria, while compression-controlled columns with high axial loads exhibit premature failure. They also proposed new expressions and parameters for assessing steel-reinforced-concrete composite columns with non-seismic details. [PERSON] et al. (2019) [90] also discussed the pros and cons for steel-reinforced-concrete composite columns under axial and seismic loads. Additionally, [PERSON] et al. (2021) [91] developed fragility and resilience functions, and assessed ASCE 41-17, examining the seismic performance of steel-reinforced-concrete composite columns. The methodology used Monte Carlo simulation techniques to establish economic vulnerability functions, and the results showed that ASCE 41-17 criteria underestimate structural capacity and resilience, while overestimate fragility and vulnerability. [PERSON] et al. (2015) [92] examined the seismic performance of composite steel-concrete columns with steel-encased profiles. It was found that composite columns with high strength concrete experienced an increase in lateral force and maximum lateral loading, while columns with normal strength concrete showed a gradual decline in bearing capacity. HSC columns exhibited a brittle failure mode but have higher energy absorption capacity, making them suitable for seismic areas. Composite columns with class C70/85 concrete demonstrated better structural performance. The fully encased composite column solution is competitive for both seismic and non-seismic zones, offering improved seismic performance and fire protection. Additionally, [PERSON] et al. (2014) [93] examined, under low cyclic reversed loading tests, twenty-six steel-concrete composite columns simulating seismic conditions. An analysis of ductility, energy dissipation, hysteresis loops, and failure patterns highlighted the influence of steel section shape, stirrup ratio, axial compression ratio, and embedded depth ratio on seismic performance. [PERSON] et al. (2021) [94] conducted an experimental and computational analysis of the seismic performance of fiber-reinforced polymer (FRP)--confined high-strength rectangular CFT columns employing high-strength thin-walled steel tubes and concrete. Aspect ratio, axial compression ratio, number of FRP layers, and fiber direction are among the factors taken into account.