Reliability analysis of a prestressed bridge beam designed in serviceability limit state as recommended by NBR 6118 and 7188


Nowadays it is known that it is important to study the safety of structures to avoid tragic accidents or economic losses. The most widely used method in the world to evaluate the safety of structures is structural reliability. The reliability index of prestressed precast beams of bridges designed using Brazilian standards (NBR6118 and NBR7188) is not known. This work evaluates the annual reliability indexes of a prestressed precast beam bridge at the serviceability limit state (SLS) projected using the Brazilian standard and compares it with results from the literature. The studied bridge has 33.5 meters of span, is simply supported, constituted by five precast concrete beams with U section. The reliability analysis was carried out using two methods for the four limit state equations: First Order Mean Value (FOMV) and First Order Reliability Method (FORM). Sensitivity analyzes were performed to consider both the relative contribution of these variables and the effect of their distributions on the annual reliability indexes for SLS. It was verified that the effect of load trains and the allowable stress significantly reduce the reliability index obtained for Brazilian standard. The service limit state equations are particularly sensitive to load trains, allowable stress and prestress losses, as well as their respective distributions.  

Author Biographies

Pedro Henrique Cerento de Lyra, Universidade de São Paulo
Doutorando na EPUSP, Professor Assistente do Instituto Mauá de Tecnologia e Engenheiro da EGT Engenharia. Engenheiro pela EPUSP em 2008 e Mestre em Engenharia de Estruturas pela EPUSP em 2011.
André Teófilo Beck, University of São Paulo
Professor Associado Departamento de Engenharia de Estruturas, Escola de Engenharia de São Carlos, Universidade de São Paulo, São Carlos, SP, Brasil. Graduou-se em Engenharia Mecânica pela Universidade Federal do Rio Grande do Sul (1996), Mestrado em Engenharia Mecânica pela Universidade Federal de Santa Catarina (1998), Doutorado em Engenharia Civil pela University of Newcastle, Australia (2003) e Livre-Docência pela Universidade de São Paulo (2013).
Fernando Rebouças Stucchi, University of São Paulo
Professor Titular Sênior da EPUSP e Sócio Diretor da EGT Engenharia. Engenheiro pela EPUSP em 1975, Doutor em Engenharia de Estruturas pela EPUSP 1991.