## 3 State of the Art
This design approach aims to optimize the elastic range resistance of PRC beams, directing structural deformation towards the ACPHs and thereby safeguarding the integrity of concrete elements. Cyclic loading experiments revealed that the strategic arrangement of the ACPHs plays a critical role in improving seismic performance, leading to increased load-bearing capacity and enhanced energy dissipation when appropriately positioned. [PERSON] et al. [30] conducted three-point bending tests on eight full-scale specimens to evaluate the flexural characteristics of the high-strength square hollow section grouted tube-sleeve connection. The results indicated that various factors, including shear key spacing, grout length, inner tube width, and steel fiber content, play a significant role in influencing the strength and stiffness of the connection. [PERSON] et al. [31] indicated that precast concrete joints with a disc spring mechanism provide better energy dissipation and seismic resilience than those using only conventional grouting sleeves. The disc spring generates a restoring force, helping to protect the concrete structure during seismic events. The analysis shows that the disc spring functions similarly to a damping system, concentrating damage in the spring region at the beam's end and diverting some damage from the core joint area. The theoretical joint deformation assessments under lateral seismic forces matched experimental findings, confirming the proposed joint's effectiveness. [PERSON] et al. [32] indicated that using reactive powder concrete (RPC) with L-shaped steel reinforcement in beam-column connections significantly enhances various structural properties. Notable improvements include load-bearing capacity, hysteresis characteristics, stiffness degradation, and energy dissipation in precast concrete joints. Despite advancements in seismic systems, gaps remain in the research. Most studies focus on single-bay, single-story subassemblies, with fewer examining multi-bay or multi-story frames that introduce complexities like column continuity and higher vibrational modes. These factors can significantly affect moment distributions and joint demands. Additionally, high testing costs limit parametric analyses on beam spans, column sizes, and reinforcement configurations, prompting reliance on advanced numerical simulations. These simulations help apply insights from validated subassembly tests to assess novel connections in full-scale buildings during real earthquake scenarios. Current design discourse emphasizes the need to address ultimate and serviceability limit states while also considering damage mitigation strategies to balance performance during both moderate and severe seismic events. A device that yields prematurely under moderate lateral loads may protect beam and column integrity but could cause excessive displacements in service-level earthquakes. Thus, balancing ductility during severe seismic events with acceptable service performance is crucial. From an analytical standpoint, the ability to promptly repair or substitute a damaged hinge is a crucial aspect of resilience. While the hinge may theoretically be replaceable, it is essential to assess the practical procedures necessary for removing the old hinge, ensuring that the main beam and column are free of damage, and efficiently installing the new component. This presents an opportunity for the construction industry to adopt standardized hinge module fabrication and establish clear replacement protocols, transforming the process into a task similar to changing a mechanical part in machinery. Furthermore, practical considerations such as the implementation of corrosion protection for the steel hinge, ensuring water-tight joints in environmentally exposed areas, and exploring the potential integration of these hinges with additional damping systems could yield significant advancements in future applications.