Computational study of the vertical impact coefficient on girders of pier access bridges

Özet

Bridges in Brazil are designed according to design code NBR 7188:2013 [1] and NBR 7187:2003 [2], in which the moving load model is composed of a three-axle vehicle. The configuration of the moving load model follows the pattern of an older version of the code, the NB-6 (1960). Despite the updating of load values, the present moving load model is not appropriate to represent the current traffic effects in Brazilian bridges. The dynamic effects induced by the moving load are taken into account by the impact coefficient, applied in the load model. The static values of the load model are obtained by multiplying its load by this coefficient. The objective of this work is to perform a dynamic analysis of bridge girders, to determine the dynamic effects, to compare with the static effects and to measure the accuracy of the impact coefficient. The results obtained for the beams, showed that for some cases, the impact coefficients had a good approximation to transform the static efforts into dynamic ones. However, in other cases, these coefficients did not show the same result. Through the study it was possible to identify that the impact coefficients provided in the code can be enhanced from[1] Associação Brasileira de Normas Técnicas. NBR 7188. Road and pedestrian live load on bridges, viaducts, footbridges and other structures. Rio de Janeiro: ABNT; 2013. [2] Associação Brasileira de Normas Técnicas. NBR 7187. Design of reinforced and prestressed concrete bridges - Procedure. Rio de Janeiro: ABNT; 2003. [3] Marchetti O. Pontes de Concreto Armado. São Paulo: Blucher; 2008. [4] Administração dos Portos de Paranaguá e Antonina. Dicionário básico portuário. Paranaguá: APPA; 2011. [5] Silva A, Barbosa O. Projeto estrutural e de fundações do Terminal Offshore de Minérios do T1 do Complexo Portuário do Açu. Congresso Brasileiro de Pontes e Estruturas. Rio de Jeneiro; 2018. [6] Leitão F. Verificação à Fadiga de Pontes Rodoviárias Mistas (Aço-Concreto) [Msc]. Universidade do Estado do Rio de Janeiro; 2009. [7] Ahi A. Análise de Fadiga em Pontes Rodoviárias de Concreto Armado [Msc]. Universidade do Estado do Rio de Janeiro; 2009. [8] Fryba L. Vibration of solids and structures under moving loads. Groningen: Noordhoff; 1972. https://doi.org/10.1007/978-94-011-9685-7 [9] Melo E. Interação Dinâmica Veículo-Estrutura Em Pequenas Pontes Rodoviárias [Msc]. Universidade Federal do Rio de Janeiro; 2007. [10] Soriano H. Introdução à dinâmica das estruturas. Rio de Janeiro: Elsevier; 2014. [11] Botelho T. Modelagem Computacional de Tabuleiros de Pontes de Concreto [Msc]. Universidade Federal do Rio Grande; 2016. [12] Rossigali C, Pfeil M, Battista R, Sagrilo L. Towards actual brazilian traffic load models for short span highway bridges. Revista IBRACON de Estruturas e Materiais. 2015;8(2):124-139. https://doi.org/10.1590/S1983-41952015000200005 new studies taking into account the dynamic analysis of loadings of Brazilian bridges.