Vessel Colission Protection for Chaco Corrientes Bridge by Means of Energy Absorbing Drilled Shafts

Abstract

The Chaco-Corrientes Bridge, officially known as Puente General Belgrano, spans across the Paraná River; a major waterway that supports heavy fluvial traffic mainly consisting of barge tows, tanker, and container barges for cargo exports from Argentina, Paraguay and Brazil. Barge tow configurations can weigh up to 20,000 metric tons and displace at velocities of up to 5.3 m/s downstream. Given the fact that existing bridge piers were not designed to resist vessel impacts, and that the existing collision protection system presents several maintenance and reliability issues, a new protection system consisting of groups of drilled shafts was designed. This protection system provides a flexible energy absorbing mechanism whereby the kinetic energy of the vessels is transformed into plastic work of the protection structure. This paper describes the nonlinear numerical model that describes the behavior of the shaft group in terms of absorbed energy for head-on and oblique impacts. Given the fact that energy is absorbed through large displacements (on the order of 10 m), the model is able to consider geometric changes and second order effects on the shafts due to the weight of the cap.
A simplified dynamic model that describes the head-on collision process, through which the time variation of energy transfer is studied, is also described.