## 1 Introduction  
Earthquakes are always seriously taken into account when designing and constructing an engineering structure such as a high-rise building, a long-span railway bridge, a sport arena, etc. [1; 2; 3; 4; 5; 6]. The influence of an earthquake on building structures can tremendously cause the losses of either lives or investments. Any landmark engineering structure can be destroyed in an instant because of the occurrence of extreme motions caused by natural disasters such as earthquakes and strong winds, or even by high-speed traffic motions [7; 8]. In a traditional seismic design of building structures, an earthquake energy input is designed to be dissipated by the plastic deformation of some significant structural members such as frame columns, beams, joints, and braces. The energy dissipation mechanism may cause some structural damages or a total collapse subjected to earthquake motions [9]. In order to alleviate the risk of seismic damages to urban infrastructures, many scholars have engaged in the research frontier of earthquake engineering and have continuously developed various technologies to improve the structural safety of a building under severe earthquakes. A passive energy dissipation system has been widely used in seismic regions to absorb the input energy of earthquake excitations. In addition, a structural seismic control is commonly adopted to change or adjust the dynamic characteristics of the structure by installing special devices (e.g., seismic isolation bearing [10; 11; 12]), some other structural modifications (e.g., energy-dissipation braces and joints [13; 14; 15; 16; 17], fluid viscous energy absorber [18; 19; 20], and metallic energy absorber [21; 22; 23; 24]), or additional substructures (e.g., tuned mass energy absorber [25; 26; 27]) in a certain part of the structure. These devices, which require no additional energy to operate, generate a controlled counterbalance force and provide the ability to improve energy dissipation in structural systems [28]. On the other hand, a passive energy dissipation device can be used as a special structural element that, when incorporated into a structure, absorbs or consumes a significant portion of the input energy. Thereby it reduces energy dissipation demand on primary structural members and minimizes possible structural damage. Engineers are constantly looking for new materials that increase the seismic performance of a building, and one of the most effective materials that have been found in recent decades is the low-yield-point (LYP) steel. The LYP steel possesses extremely low yield strength, low yield ratio, and high elongation capacity much larger than that of conventional structural steel. It also exhibits excellent strain hardening characteristics when subjected to cyclic loads [29; 30; 31]. With a low yield ratio, the structure that utilizes LYP steel can redistribute the inelastic stress easily and provides a larger plastic zone. Due to its superior deformation capacity, researches on the application of LYP steel in building structures in the forms of shear walls can be found [32; 33; 34]. The LYP steel is also frequently adopted in hysteretic metallic energy absorbers. The advantages of LYP steel energy absorbers as a novel kind of passive energy dissipation device include simple conformation, stable hysteretic performance, low cost, and explicit early-warning mechanism under earthquake action. Significant attention has been paid to the development as well as the seismic evaluation of LYP steel energy absorbers, so as to remarkably improve the performance by decreasing any damage of the parent structure [35; 36; 37; 38; 39; 40; 41]. The LYP steel hysteretic energy absorbers applied in the buildings are designed to reduce the dynamic responses of drift and stress, which utilize the considerable plastic deformation to absorb the input energy under earthquakes or other natural forces.