CONSIDERATIONS ABOUT APPROXIMATE AND RIGOROUS METHODS FOR ANALYSIS OF REINFORCED CONCRETE BRIDGE DECK

Resumo

This paper presents an evaluation of the approximated methods for the calculation of
reinforced concrete bridge deck, considering the available numerical resources. In the past, it was
common to use simplifications in the calculation of the constituent elements of the bridge: the
superstructure and substructure, on the definition of the internal forces on the ultimate limit state
(ULS) and the displacements on the serviceability limit state (SLS). From this trivial analysis, usually
analytical, the verification of the parameters of the structure was made. It is known, however, that the
simplified structural analysis causes eventual inaccuracy on the internal forces and deflection values of
the bridges and viaducts, since it is not considered the real interaction, three-dimensional, between the
main constituent elements of the structure: bridge deck, girders, columns, abutments, wing walls and
foundation elements. Thus, an oversizing of the inputs is done, for example, consumption of steel and
concrete, thus, burdening the project in question. Considering the above, it was intended in this
research to make a comparison of the results obtained analytically in a reinforced concrete slab bridge
with the results using the tables of Rusch [1] taking into account the moving loads based on Brazilian
Technical Standards NBR 7188 [2] and NBR 7187 [3]. The analyzed bridge has two spans and total
lenght of 23.10 m, with central reinforced concrete pier. The abutments are closed and have, each one,
two wing walls, simultaneously acting as containment element and columns. For the analysis of the
bridge moving load, was considered the standard Brazilian vehicle class TB-450. Finally, after a
systematical analysis of results obtained from the analytical and numerical models of the bridge, some
considerations are made, especially regarding the use of simplified methods of structural analysis and
design.