In contrast to irregular waves, the measurement of nonlinear wave-induced vibration phenomena in regular waves is a scarce occurrence. This phenomenon can only be observed when the wave frequency is an integer multiple of the springing frequency. Through the superposition of regular waves onto irregular wave systems and the consideration of second-order hydrodynamic forces, an in-depth analysis of the nonlinear hydroelastic response is conducted, leading to the derivation of time-history curves for nonlinear springing and structural bending moments. This study applies nonlinear hydroelastic theories and computational methodologies to solve the nonlinear vibration responses of containerships caused by frequency doubling, and these solutions are subsequently compared with the outcomes of self-propelled model tests. The motion and load response curves obtained from ship model experiments are carefully examined. Employing frequency spectrum analysis and time-history band-pass filtering techniques, the low-frequency and high-frequency components of the responses are successfully extracted. A detailed comparison is made between the numerical results of the current study and the experimental data. The vertical motions and vertical bending moments of nonlinear wave-induced vibrations are computed using the frequency-domain nonlinear analysis approach of three-dimensional hydroelasticity. When integrated with data comparison, a remarkable degree of congruence is found between the calculated and experimental motions and loads under head waves. This finding strongly validates the feasibility of the frequency-domain nonlinear hydroelastic method for assessing nonlinear wave-induced vibration responses in regular waves.