# Behaviour Investigation of SMA-Equipped Bar Hysteretic Dampers Using Machine Learning Techniques
## 1 Introduction  
There are several techniques that can be used for improving seismic behaviour in structures [1, 2, 3, 4]. Adding certain elements to the structure, such as shear walls or steel braces, would enhance the seismic strength of the structure. Due to this fact, the lateral stiffness of the structure is increased, and the increased lateral stiffness will develop the force applied to major structural components [5, 6, 7]. Increasing the seismic behaviour of structures can be enhanced by insulating the foundations from the supports. Despite strengthening strategy of structural elements affected by lateral loads, isolated structural elements without any strengthening could be an alternative. When the seismic demand in isolated systems is reduced, the structural performance can be enhanced without affectingmain elements by increasing their internal forces. For the isolators to withstand the vertical forces of the structure, they should be sufficiently stiff in the vertical direction [8; 9; 10]. Although to reduce the overall lateral stiffness of the structure and increase its time period, the stiffness isolators should be significantly lower horizontally than vertically. Isolators, in general, are low dampened, and adding additional dampers in some circumstances can increase dampening and decrease the displacement of the isolation systems [11]. Despite causing an increase in the force applied to the isolation system, utilising added dampers may generally minimise the displacement of the whole structure. Therefore, dampers and their impact on the performance of isolated structures should be thoroughly examined [12]. Recently, some new machine learning and artificial intelligence techniques were utilised to solve complicated civil engineering problems related to bridges [13; 14; 15]. There are different kinds of dampers, among which are steel hysteretic dampers, which attract the interest of many researchers due to their durable hysterical behaviour, high potential in energy dissipation, long-term robustness, low production cost, and simple replacement and installation [16; 17]. In these dampers, plastic deformation occurs through bending, shear, torsion, or the aforementioned mechanisms that deal with energy dissipation. Researchers such as [PERSON] [18], [PERSON] [19], [PERSON] et al. [20], and [PERSON] et al. [21] were the first to introduce the idea of using steel as a damper. Known as the added damping and stiffness (ADAS) tool, it has been introduced in several types; [PERSON] and [PERSON] [22] developed a well-known type of damper with X-shaped steel plates and connected parallel to base plates of structures. The triangular-shape-added damping and stiffness (TADAS) was then introduced by [PERSON] et al. [23]. Similar to the ADAS dampers, in TADAS dampers, both ends of steel triangles are attached to the base plates. Many other researchers investigated the behaviour of ADAS X-shaped and triangular dampers [24; 25]. [PERSON] et al. [26] and [PERSON] and [PERSON] [27] proposed the rhombic ADAS dampers using low-strength steel with pinned joints at each end. Their observation was that the pinned joints at both ends of the damper prevent the plate from being subjected to unwanted axial forces. In addition, the mechanical characteristics of low-strength steel improve energy absorption and damper ductility. [PERSON] et al. [28] conducted additional experiments on rhombic ADAS dampers. The slit steel damper (SSD), composed of a wide flanged steel section with seamless rounded ends, was proposed by [PERSON] and [PERSON] [29]. Other research works have also been conducted to evaluate steel damper behaviour [30; 31; 32; 33; 34; 35]. A shear panel damper (SPD), which contains a steel plate linked to two upper and lower panels, has also been proposed and investigated by some researchers [36; 37; 38; 39; 40; 41]. [PERSON] et al. [42] developed a comb-teeth damper (CTD), which comprises steel plates that resemble comb teeth.