Live load models for highway bridges based on provincial traffic data

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University of New Brunswick


This thesis assesses the site-specific live load spectra in New Brunswick and the adequacy of the Canadian Highway Bridges Design Code (CAN/CSA-S6-14) CL-625-ONT live load model, which is used by the New Brunswick Department of Transportation and Infrastructure (NBDTI) for design and evaluation of highway bridges. In the past few decades, the heavy traffic loads have significantly increased and as presented in this thesis, the CL-625-ONT does not sufficiently represent the alterations in the local traffic conditions. As a result, two idealized live load models were developed to reflect the following: (1) normal traffic enforced by provincial laws and regulations; (2) nonconforming vehicles that are allowed to operate in the provincial highway bridge network under special permits. The proposed models were developed using a multiobjective optimization-based approach. The live load is quantified using an extensive Weigh-In-Motion (WIM) database from five sites in New Brunswick and a database containing permit applications that were approved by the NBDTI between 2014 and 2018. Four bridge configurations were considered in this study based on the provincial bridge inventory with spans ranging from 2m to 80m. The proposed live load models can further assist the NBDTI for the design and evaluation of medium and short span highway bridges in New Brunswick, as the findings presented in this thesis show that the CL-625-ONT load model is no longer representative of the current local traffic conditions.