Comparação dos esforços solicitantes em vigas longarinas de uma ponte obtidos pela aplicação das normas ABNT NBR 7188 (2013) e AASHTO LRFD (2020)

Abstract

Bridges have, in addition to their functional relevance, a symbolism related to technological advancement, represented by the complexity of their structures and their economic impact, enabling efficient transportation of various types of loads. This study presents different bridge models concerning their structural system, with a particular focus on “Beam Bridges”, as it is the type of bridge under investigation. The aim was to assess the characteristic bending moment and shear forces in the longitudinal beams of a real bridge, considering the loadings and procedures recommended by the Brazilian standard ABNT NBR 7188 (2013) and the American standard AASHTO LRFD Design Bridge Specifications (2020). The bridge has a 15 m span between supports, and the width of the cross-sectional section is 6 m. Its superstructure consists of four main beams (stringers) bi-supported with an I-section and connected to the deck, which has a thickness of 20 cm. The beams are equally spaced at 1.60 m from their center and the bridge has been designed for only one traffic lane. The Fauchart method considersthe flexibility of the deck in distributing loads among the beams and was used to evaluate the load distribution in the analyzed bridge. It was concluded that for the exterior beams the Brazillian standard yielded bending moment results 45% higher than the American standards, and 30% higher in shear values. In the interior beams, the bending moment values found were 52% higher when analyzed using NBR 7188 (2013), while for shear forces the values obtained with AASHTO LRFD (2020) were 10% higher compared to the Brazilian standard.