Hydroelastic responses of damaged plate-type VLFS under combined regular wave and two-axle spatial moving vehicle loading

Very large floating structures (VLFSs) used for transportation and offshore infrastructure may experience altered hydroelastic responses as structural damage accumulates. This study develops a hydroelastic vehicle-structure interaction framework for damaged plate-type VLFSs under combined regular waves and two-axle spatial moving vehicle loads. Linear potential-flow theory and the boundary element method are used for hydrodynamics, while Kirchhoff plate theory and the finite element method describe the floating plate. Damage is represented by cracks aligned with local x - and y -axes and incorporated through the additional flexibility matrix approach, and vehicle dynamics are modeled with a seven-degree-of-freedom mass-spring-damper system. The coupled equations are solved using the Newmark- β method and validated against benchmark solutions for hinged floating structures and intact VLFSs under combined wave-moving-load actions. Parametric studies examine lane arrangement, flexural rigidity, damage extent, and multidirectional damage distribution. Vehicle-induced responses reach approximately 23% of the wave-induced responses. Increasing damage length from 10 to 60 m increases maximum displacement by up to 57% under severe damage conditions, while multidirectional damage produces more pronounced local responses when damage regions coincide with vehicle trajectories. The framework provides a computational basis for future serviceability and structural assessment of damaged floating transportation infrastructure.