# Preliminary Study on the Damping Effect of a Lateral Damping Buffer under a Debris Flow Load
## 1 Introduction  
Debris flows can cause serious damage to infrastructures and threaten lives. There have been a considerable number of debris flows involving the destruction of mountain villages and small towns, such as the disasters which occurred in Venezuela in December 1999 [1] and in Zhouqu, China, in August 2010 [2]. Mountainous areas with low vegetation cover and up-and-down landform are extremely vulnerable to debris flows. Therefore, buildings in these mountainous areas are prone to damage by debris flows. Actually, buildings play an important role in resisting debris flows. Hence, drastic measures are urgent to ensure buildings withstand such kinds of disasters. Studies on buildings against debris flows specifically are relatively deficient; however, there is still some research involving mitigation measures to reduce the damage by debris flows and the interaction between debris flows and buildings [3, 4]. Debris flow mitigation measures can be categorized into two classifications, namely engineering measures and non-engineering measures [5]. Meanwhile, engineering measures include drainage systems [6, 7], check dams [8, 9, 10], and flexible barriers [11], etc., while non-engineering measures involve disaster warning and evacuation systems, retrofitting and reinforcement of buildings [12], etc. In this paper, the main goal is to propose some specific structural measures to reduce the damage to buildings caused by debris flows from the perspective of building retrofitting. It is known that debris flow is characterized by high velocity, strong striking force and severe destruction [13]. Therefore, if prevention measures are based on reinforcement, the construction cost would be drastically high, while the safety of buildings still cannot be guaranteed for the randomness of debris flows. Therefore, people should seek a method to retrofit buildings with some devices or equipment of a lower cost. On the other hand, the application of structural vibration control in aseismic engineering field provides a new solution to this problem. In civil engineering, the systematic knowledge of structural vibration control was first introduced by [PERSON] [14], and structural control plays an important role in engineering nowadays [15; 16; 17]. It is a typical method to attach devices [18] or to study the failure modes [19] to prevent structures from being destroyed under earthquake. Moreover, in the field of vehicle control, the semi-active suspension [20; 21; 22; 23] and active suspension [24] play an important role in guaranteeing both safety and comfort of cars. In this way, devices or equipment suitable for different structures or applicable to different scenarios (e.g., [25; 26; 27; 28; 29; 30]) are put forward to reduce the structure's response under different dynamic loads. Enlightened by various structural control methods [25; 26; 27; 28; 29; 30] and semi-active suspensions [20; 21; 22; 23] as well as active suspensions [24], a lateral damping buffer is proposed to retrofit buildings in debris flow-prone areas. Specifically, it is a combination of traditional buffer and shock absorber. By attaching such devices to existing buildings, the structures' debris flow resistance can be enhanced a lot, especially when the loading level is high; the maximum acceleration response can be reduced by nearly half. In addition, the construction is fairly simple because the buffer can be directly attached to the existing structure without large-scale reconstruction. To examine the performance of the lateral damping buffer, an impact test of such a device attached to a two-degree-of-freedom (DOF) structure under a simulated debris flow load is completed. In China, there are mainly three types of domestic structures in mountain regions of the western area, namely, reinforced framed structures, masonry structures, and reinforced masonry structures [31]. In this paper, we take a frame structure as an example to study the effect of the buffer. Then, a numerical simulation is performed to validate its rationality.