## 1 Introduction
[22] confirmed that under abnormal near-fault earthquakes, the deck of a cable-stayed bridge may vertically disengage from the shear key at the beam pier connection, and they observed that significant lateral displacement at the deck end can lead to damage near the intersection with tower decks. [PERSON] et al. [23] investigated the combined effects of vertical ground motion (VGM) and horizontal ground motion (HGM) on damage modes and sequences in long-span cable-stayed bridges. VGM had minimal impact on the bearing damage probability but adversely affected the tower and pier damage probability, shifting vulnerability from bearings to piers and towers. [PERSON] et al. [24] designed and constructed a 70/1400 scale model of a 1 m span, cable-stayed bridge to study its seismic response and potential failure mode under lateral seismic excitation. [PERSON] et al. [25,26] conducted an elastoplastic analysis on an actual long-span cable-stayed bridge to investigate the damage and failure modes of the structural system when subjected to seismic waves along both longitudinal and transverse directions. The evaluation index used was the Park damage index. [PERSON] et al. [27] investigated the macroscopic manifestations and microscopic failure phenomena of earthquake-induced damage in buried pipelines, categorizing them into three categories and nine typical failure modes. They also summarized the causes and failure mechanisms associated with each mode. [PERSON] et al. [28] utilized ANSYS software to simulate the entire process of a model under earthquake loading, from stress analysis of concrete units to gradual failure of tower feet leading to instability of the bridge tower. [PERSON] et al. [29] discussed control strategies for preventing collapse in cable-stayed bridges, including high-damping rubber bearings, fluid viscous dampers, and locking clutch control methods, and they demonstrated that these three collapse control methods can enhance the anti-collapse ability of bridge specimens while achieving a delayed collapse time, as desired. [PERSON] et al. [30] successfully employed the Wiener entropy of strain measurements as a reliable tool to detect and assess multiple damages of varying sizes and severities in a buried steel pipeline model, demonstrating its viability. Building upon this, we apply the fluid-solid coupling method to analyze the seismic response of oil and gas pipelines straddling a cable-stayed pipe bridge in this study. The ANSYS software, along with other finite element tools, is utilized to establish a fluid-structure coupling model for the oil and gas pipeline, cable-stayed pipe bridge system. We conduct an analysis on the total deformation and equivalent stress experienced by the oil and gas pipeline under both calculation methods, revealing insights into how fluid-structure coupling affects its failure mechanism. Furthermore, we delve into discussing the failure mode of the cable-stayed pipe bridge oil and gas pipeline structure system resulting from interactions among various components, while also defining different types of damage inflicted upon the oil and gas pipeline due to these interactions. These findings provide valuable references for seismic design, construction methodologies, and mechanical model analyses pertaining to straddle-type oil and gas pipelines.