## 8 Composite Construction and Foundation Seismic Design
### Composite Construction and Foundation Seismic Design: State-of-the-Art
Direct force transfer from the wall to the anchors was made possible by the connection of the anchors to the bottom of the faceplates, which eliminated the baseplate from the force transmission chain. LS-Dyna software ([[https://lsdyna.ansys.com/](https://lsdyna.ansys.com/)]([https://lsdyna.ansys.com/](https://lsdyna.ansys.com/))) was used to verify three test walls. It was discovered that the split-baseplate connection with concentric anchors was more resilient than the other connections. [PERSON] et al. (2016) [135] examined the direct shear behavior of rebar-coupler anchor systems used in nuclear reactors to secure steel-plate composite walls to the concrete basemat. The anchor specimens were subjected to extensive testing up to failure. The results showed the load-slip displacement responses, direct shear strength, and failure mode. It was found that the American Concrete Institute (ACI) 349 code equation underestimated the shear strength because it assumed that failure occurred in the rebars, while in reality, it happened in the couplers. An updated design equation using the net shear area of the couplers improved the accuracy of calculating shear strength. An empirical model for the shear force vs. slip displacement response of rebar-coupler anchor systems was also proposed with the use of experimental data. Analytical models were developed by [PERSON] et al. (2024) [136] to determine the minimum depths required for connecting circular and square concrete-filled steel tubular columns. The pullout capacity of the reinforced concrete footing, which was reliant on the strength of the footing concrete, reinforcement, and cement grout, was equivalent to the pullout strength of the tube in the models. These models were used to calculate the optimal depths for composite columnsusing the Monte Carlo simulation technique. The second connecting scheme showed significant improvements over the first scheme, with 37.3% and 45.2% reduced embedment depth for circular and square composite columns, respectively. Additionally, to address concretes-filled steel tube column damage during seismic load, [PERSON] et al. (2024) [137] suggested a rubberized concrete-filled corrugated steel tube composite column-foundation connection. Experimental studies confirmed improved ductility and energy dissipation. The results showed sufficient connection strength under seismic load and proposed seismic design methods using a side shear database to inform future column-foundation connections. [PERSON] et al. (2020) [138] examined the structural behavior of double-pile foundations under cyclic loads. The effects of inclination angles and the embedment depths of unequal-height concrete-filled steel tube piles on failure modes, ductility, stiffness, strength, and energy dissipation capacity were evaluated. Battered piles increase loading capacity and energy dissipation but decrease deformation capacity and ductility. Unequal heights of battered composite piles can lead to premature failure of the shorter pile. Unequal heights also decreased the deformation capacity of the foundation. [PERSON] et al. (2020) [139] examined a steel composite hollow reinforced concrete column, characterized by an inner tube within the hollow section, which required innovative connecting techniques for the column-footing joint segment. They introduced three novel connecting methods, which were assessed through experimental and finite element analysis investigations. Subsequently, upon identification of an effective connecting method for column footing joints, it was implemented in large-scale test specimens to validate and assess its performance. An analysis of composite pile performance was conducted by [PERSON] et al. (2021) [140], comprising a comprehensive dataset of 79 bending tests, which facilitated the comparison of observed bending moment capacities against theoretical predictions derived from various design guidelines. However, the assessment of composite pile behavior necessitates consideration of drift capacity predictions for a more thorough evaluation.