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July 21, 2026Journal of Marine Science and Engineering0 citationsOpen Access

A Study on the Dynamic Ultimate Bearing Capacity of Box Girders Under Combined Hydrostatic Pressure and Whipping-Type Dynamic Bending Loads

YWYì WángBGI Group (China)YWYongjun WangBeijing University of Posts and Telecommunications JTJie TangShenzhen University

Key Points

This research aims to evaluate the dynamic ultimate bearing capacity of box girders under hydrodynamic whipping and bending loads.
A nonlinear dynamic finite element model is developed for box girder analysis.
Stochastic finite element analysis and Monte Carlo simulations are conducted to assess the effects of material randomness and loading strain rate.
Geometric and material nonlinearities are included in the modeling.
Dynamic ultimate bearing capacity increases with strain rate, peaking at a strain rate of 2.306 s−1.
Greater initial geometric imperfections lead to a marked decrease in ultimate capacity.
Higher mean load effects significantly raise failure probabilities, but lower mean load effects with increased standard deviation decrease structural reliability.

Abstract

Hydrodynamic actions on ships may excite hull-girder whipping and generate short-duration global dynamic bending effects in the structure. To investigate the dynamic ultimate bearing capacity of box girders under such hydrodynamically induced whipping-type dynamic bending loads, a simplified box-girder structural segment is studied in this paper. A nonlinear dynamic finite element model is established under the combined action of hydrostatic pressure and equivalent whipping-type dynamic bending loads. Instead of directly applying localized slamming pressure, opposite rotational velocities with equal magnitudes are prescribed at the end reference points to equivalently represent the global bending response associated with whipping. This treatment allows the load-carrying characteristics and failure behavior of the box girder under transient dynamic bending to be examined. Geometric nonlinearity, material nonlinearity, the Cowper–Symonds strain-rate effect, and initial geometric imperfections are considered in the model. Stochastic finite element analysis and Monte Carlo simulation are further used to evaluate the influence of the randomness of Young’s modulus and loading strain rate on the probability distribution of the dynamic ultimate bearing capacity and structural reliability. The results show that the dynamic ultimate bearing capacity of the box girder increases with increasing strain rate, while its sensitivity to the strain rate decreases markedly when the strain rate exceeds 2.306 s−1. A larger initial geometric imperfection amplitude leads to a more evident reduction in the ultimate capacity. The reliability analysis shows that an increase in the mean load effect significantly increases the failure probability; when the mean load effect is lower than the mean ultimate bending moment, an increase in the load standard deviation reduces structural reliability. This study provides a fundamental numerical reference for predicting the dynamic ultimate bearing capacity and conducting probabilistic safety assessment of box-girder structures subjected to whipping-type global dynamic bending.

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