## 1 Introduction
### Research Status of the Shear-Type Metal Damper  
Many scholars have conducted extensive research on the behavior of metal dampers used in structural systems. Metal dampers as passive energy dissipation devices commonly serve as non-structural members reciprocating to absorb the input seismic energy and protecting the structural members. This energy dissipation is obtained by plastic deformation in which the structural member is in elastic [19]. Low-yield-point steel has the advantages of low yield strength, large elongation, and good ductility. Its high plastic deformation ability could enhance the structural energy dissipation ability [20]. The shear metal damper proposed by [PERSON] was widely used in the damping design of building structures due to simple structure and excellent performance. [PERSON] et al. [21] proposed geometrically optimized X-shaped mild steel dampers and triangular soft steel dampers. [PERSON] and [PERSON] [22] experimentally researched different ways of weakening the stiffness of the damper in which the shape in the middle has a great influence on the ductility and the flange plates of different shapes have no obvious influence. [PERSON] et al. [23; 24; 25] conducted experimental research and simulation on the hysteretic behavior of low-yield steel shear dampers. [PERSON] et al. and [PERSON] et al. [26; 27] proposed a damper with a circular cross-section by geometrically optimized parameter analysis. In order to solve the connection problem between lead blocks and components, [PERSON] et al. [28] proposed a baffle-type lead damper and its test results demonstrated excellent energy consumption ability. According to the above study, metal dampers could achieve good energy dissipation ability but their failure would result in degradation of the structural stiffness. To some degree, the high rigidity of in-cast structural systems would limit the performance of dampers and the stiffness degradation of the prefabricated structures would result in the collapse especially in large and super-large earthquakes. U-shaped metal yield damper introduced by [PERSON] et al. [29] has been tested about its mechanical displacement, lateral strength, elastic stiffness, and energy dissipation ability. [PERSON] et al. [30] developed a detachable buckling restrained shear plate shock absorber. The influence of key design factors, such as the length-width ratio of the slab and the number of internal composite plates, on the seismic performance of the damper, is studied, and the design formulas for calculating the elastic stiffness and ultimate strength of the damper are proposed. [PERSON] et al. [31] proposed a metal shear plate damper with an optimized shape. The test results show that the metal shear damper has stable energy dissipation capacity and good low cycle fatigue performance. [PERSON] et al. [32] proposed that the use of passive energy dissipation and re-centering devices could limit the structural damage. [PERSON] et al. [33; 34] successfully proposed a design procedure for the damper braces to attain a designated performance level according to a certain proportion of reinforcement and further developed a new displacement-based design procedure to proportion hysteretic damped braces considering the effect of a structure's seismic degradation. These procedures are verified to be highly effective when being utilized in designing frame structures. Some gap dampers are proposed by [PERSON] et al. [35] and [PERSON] et al. [36] which could be designed to be engaged after an expected displacement and they depict good performance when being utilized in base-isolated structural system. Therefore, an innovative type of wall-to-wall horizontally connecting structure with high energy dissipation and stiffness lifting ability is proposed, which is expected to enhance the seismic and resilient performance of prefabricated shear wall systems.