Dynamic pressure and displacement response of pipelines in cable-stayed bridge under the coupling effect of earthquakes and crude oil flow

• Pioneered cable-stayed pipe bridge-fluid-structure coupling model. • Quantified fluid-flow vs. seismic-induced pipe deformation/hydrodynamics. • Developed seismic-resistant oil pipeline design framework. • Created high-precision cross-disciplinary dynamic response algorithms. This study develops an innovative two-way fluid-structure coupling model for cable-stayed pipeline bridge-crude oil systems under combined seismic-fluid excitation. By coupling the VOF multiphase model with structural dynamics equations, we achieve the first integrated simulation of earthquake-crude oil flow interactions throughout cable-stayed bridge systems using actual El Centro seismic excitation and transient crude oil flow characteristics . Employing a bidirectional fluid-structure interaction approach, we applied a 20-second El-Centro earthquake waveform to the system in steady flow. The simulation results revealed that it took approximately 65 s for the crude oil to fill the pipeline, and then achieved a steady flow state by 120 s. The deformation of the cable-stayed bridge pipeline was progressively influenced by the flow location of the crude oil and inherent boundary conditions, and it eventually stabilized. The dynamic pressure of the crude oil increased rapidly, then fluctuated, and finally stabilized. However, following the ground motion, fluctuations in the crude oil’s dynamic pressure and vibrations in the pipeline did not cease immediately but gradually decreased, stabilizing around 145 s. These characteristics were consistent with the results from experimental models. Furthermore, the density of the crude oil within the system significantly affected the dynamic pressure, which increased with density over the 150-second period. These findings provide a theoretical basis for monitoring seismic responses and measuring dynamic pressure in oil pipelines.