# Dynamic Damage Mechanism and Seismic Fragility Analysis of an Aqueduct Structure
## 1 Introduction  
The aqueduct is a water conveyance structure commonly used for irrigation, water transfer, and supply in water conservancy projects. The construction of the aqueduct structure can not only alleviate the severe water shortage disaster for human beings, but also contributes to the local economic, science and technology, and social development, achieving the main sustainable development goals (SDG) that are employed by the United Nations (UN) Agenda, such as the Valens Aqueduct (Turkey) [1]. The structural type of aqueduct is mainly divided into rectangular, semicircular, U-shaped, and so on [2, 3]. Its dynamic response law under seismic loads has always been at the center of. [PERSON] et al. [4] considered the concrete elastoplastic random damage constitutive relationship and the random seismic excitation model to carry out a random nonlinear seismic response analysis of the double trough aqueduct structure. The results showed that the response value of the mid-span bottom plate and the pier bottom of the aqueduct is relatively large, whichbelongs to the weak position of earthquake resistance. [PERSON] et al. [5] studied the foundation soil property on the dynamic characteristics and responses of rectangular aquducts. The results show that the increase of the soil stiffness causes amplification in impulsive displacement. [PERSON] et al. [6] studied the influence of aquduct height on the structure and proved that the higher aquduct has a greater structural dynamic response. Some researchers have looked into the dynamic failure process of aquduct structures under earthquake ground motion, taking into account the effect of fluid-structure interactions [7; 8; 9; 10]. [PERSON] et al. [11] proposed a simplified beam-water coupled system to investigate the seismic ground motion response to long spans of large-scale aqueduct structures. The traditional seismic dynamic analysis focuses on the dynamic response of the aqueduct structure itself under the action of ground motions, which can directly reflect the actual conditions of the aqueduct structure under seismic excitation. Most of the large-scale aqueduct structures studied by researchers today are in areas prone to earthquakes. Research on the damage and collapse of aqueduct structures under powerful earthquakes is critical to the structural safety assessment of engineering procedures to assure the safety of aqueducts and normal regulation of water resources during strong earthquakes. Performance-based seismic engineering theory collectively refers to the damage analysis and seismic response analysis in the structural earthquake-resistant evaluation as a seismic fragility analysis [12; 13; 14]. [PERSON] et al. [15] first proposed the idea of an incremental time-history analysis, which [PERSON] and [PERSON] [16; 17] perfected as the earliest method of incremental dynamic analysis. The aqueduct structure is similar to bridge structures in terms of engineering design. The pier shaft is responsible for sustaining the superstructure and affecting the overall stability of both structures. [PERSON] et al. [18; 19] proposed an efficient procedure for the collapse mechanism evaluation of existing reinforced concrete motorway bridges under horizontal loads, providing useful information for the maintenance of existing bridges in terms of repair and strengthening interventions. In recent years, various researchers have applied IDA to the construction of frames, tunnels, bridges, and other fields [20; 21; 22; 23]. However, the probability of structures exceeding the damage index under the action of earthquakes may not strictly increase with the ground motion record IM in a large number of numerical simulations. This statistical probability method of incremental dynamic analysis may not accurately give the corresponding value when the structure reaches a limit state. Therefore, the seismic fragility assessment may be limited. In 2003, [PERSON] [24] proposed the MSA, a fragility analysis method using discrete IM.