Numerical Modeling and Dynamic Response Analysis of an End-Anchored Floating Bridge With a Damaged Pontoon Under Repair Operation

Abstract

Floating bridges face potential hazards due to ship collisions throughout their operational lifetime. In a situation where a pontoon is significantly damaged from an accident, a floating drydock may be used to compensate for the lost buoyancy and provide a dry atmosphere for operations. As the repair might take months, a primary concern is whether the repair can be in-site conducted without shutting down the road traffic. This study aims to investigate the feasibility of using a drydock for the repair. The numerical model of the in-operation damaged bridge is established for a comparative dynamic analysis with the intact end-anchored bridge. Eigenvalue analysis is conducted, and pendulum modes of oscillation are found with an eigen-period of around 15 s. The dynamic responses are analyzed through a series of fully coupled time-domain simulations under various environmental conditions. The results indicate that the standard deviation of the moment about the girder weak axis increases significantly at the damaged pontoon axis due to the excitation of low-frequency resonant response. Swell wave loads might induce dynamic amplification to the damaged bridge, even with a relatively small wave height. In addition, the internal stress of the bridge girder is investigated and found to be larger, especially, at the lower locations of the cross section. It is suggested that the responses can be managed by limiting the excitation of pendulum modes or providing special damping devices in practical engineering.