This paper deals with analyses and reduced scale tests carried out to validate the design of flexible protection structures for bridge piers against ship impact. The protection system analyzed is part of the fixed link currently under construction across the Parana River between the cities of Rosario and Victoria in Argentina, and it will protect a cable-stayed bridge and parts of the approach viaduct against impact of aberrant vessels with sizes up to 100,000 DWT. The protection system was designed on the basis of dissipated energy and consists of groups of steel-encased large diameter concrete piles connected at the top by a reinforced concrete platform. The impact energy is to be absorbed by large horizontal displacements of the pile caps that involve large deformations of the surrounding soil and geometrically and material nonlinear response of the pile shafts themselves. The paper focuses on modeling the nonlinear characteristics of the response of the structure, and on its assessment by means of 1:15 scale model tests performed in both the laboratory and in the field to account for the displacements and deformations undergone by the pile shafts.
IntroductionThe Santo Tome -Sao Borja road bridge between Argentina and Brazil over the Uruguay River has two vehicle lanes and two pedestrian walkways.It was opened to traffic in January 1998 after 16 months of construction and consists of 33 simply supported spans of 42.5() m. The superstructure. formed by three precast post-tensioned U-shaped girders and a cast-inplace concrete deck slab. is supported by planar portal-frame piers made of two piles embedded into the sound basalt foundation. The piles of the central 18 spans (1.50 or 1.80 m in diameter. 24 m above the top of the foundation rock) were built with steel casings from a barge moored in the river. The river has a flow of about 2.5 m/s and a water depth of 10 m. Because it is difficult to perforate the foundation rock under such conditions, static and dynamic tests were performed during and after completion of construction. These tests assessed the effectiveness of the provisions adopted during the design stage in order to keep horizontal displacements along the bridge axis within acceptable values. The longitudinal layout and a typical transverse section of the bridge are given in Figs I and 2. The piers close to the river banks (piers 1-7 and 27-32) have piles of smaller diameter (1.30 m and 1.50 m. respectively) due to the considerable lateral restraint provided by a layer of sand overlaying the foundation rock. Since the piers within the course of the river do not have any lateral restraint from soils, the stiffness of piers 8 and 26 was increased byproviding them with four piles. instead of two, in a spatial arrangement. This added stiffness, although not accounted for in the original design. was aimed at limiting second-order effects in the piles at the ends of the central sector of the bridge. A typical pier in the main river channel is shown in Fig. 3.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations鈥揷itations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.