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<div>The design of bridges prior to 1994 was carried out by either the Load Factor Design (LFD) or the Allowable Stress Design (ASD) methodologies. Load rating of these bridges was primarily conducted by Load Factor Rating (LFR). In 1994, the American Association of State Highway and Transportation Officials (AASHTO) developed and encouraged the use of a probabilistic-based method titled Load and Resistance Factor Design (LRFD) for carrying out bridge design. A new methodology consistent with LRFD was also developed and adopted for conducting load rating. Thus, a new Load and Resistance Factor Rating (LRFR) was adopted by AASHTO in 2001 for load rating. Today, the bridges that were designed by the old LFD methodology are rated by both LFR and LRFR. Continued development suggests that load rating in future will be based only on LRFR, therefore LRFR is the recommended method for carrying out load rating of bridges even if they were designed by LFD. </div><div><br></div><div>The Indiana Department of Transportation (INDOT) came across some LFD designed bridges which were adequate by LFR methodology, i.e., produced a rating factor of more than 1.0, but inadequate for LRFR. The load ratings were carried out using AASHTOWare Bridge Rating (BrR) software. These bridges belonged to five different limit states: lateral torsional buckling, changes in cross-section along the member length, tight stringer spacings, girder end shear and moment over continuous piers. </div><div><br></div><div>This research study explores the inherent differences between LFR and LRFR to justify the inconsistencies in the rating values. To find an explanation for these discrepancies, load ratings of these bridges were carried out extensively on AASHTOWare BrR. To verify the results produced by BrR, a separate analysis was also conducted using Mathcad and structural analysis results from SAP2000 for comparison purposes. Finally, the study also recommends some modifications in the BrR software that can be adopted for each of the above-mentioned limit states to resolve inconsistencies found between LFR and LRFR rating values. </div><div><br></div>

Durante los últimos años, muchos países no presentan una cultura de mantenimiento de puentes. En Latinoamérica, especialmente en Perú, aún están en la etapa de implementación de estas nuevas metodologías en la norma, mientras que otros países presentan normativas actuales adaptadas a sus condiciones. Por este motivo, la presente tesis tiene como objetivo realizar la evaluación puentes vehiculares urbanos de concreto sobre ríos torrentosos adaptadas a las condiciones peruanas resaltando con mayor detalle los elementos estructurales más relevantes e influyentes en la seguridad. Esta investigación consta de dos etapas: una inspección a detalle según la normativa del Ministerio de Transporte y Comunicaciones (MTC) y la aplicación de la metodología por Factor de clasificación de carga y resistencia (LRFR) del AASHTO (2011). La primera etapa se divide en dos tipos de inspecciones. En primer lugar, es una inspección inicial para la recopilación de información general de una población de diez puentes de los cuales se escogió tres puentes como muestra (Nicolás Dueñas, El Ejército y Corpac). En segundo lugar, se realizó una inspección rutinaria a los puentes de la muestra para determinar el estado de condición de los componentes. Después, a partir de la última inspección, se desarrolló la evaluación estructural de la superestructura a través de la metodología LRFR en los puentes de la muestra. Finalmente, se muestran los resultados, análisis y se plantean propuestas de mejora validadas por juicios expertos a partir de la experiencia de aplicar en el caso de estudio. / During the last few years, many countries do not have a culture of bridge maintenance. In Latin America, especially in Peru, they are still in the stage of implementing these new methodologies in the standard, while other countries present in their current regulations adapted to their conditions. For this reason, the present thesis aims to carry out the evaluation of urban concrete vehicular bridges over torrential rivers adapted to Peruvian conditions, highlighting in greater detail the most relevant and influential structural elements in safety. This investigation consists of two stages: a detailed inspection according to the regulations of the Ministry of Transport and Communications (MTC) and the application of the methodology by Load and Resistance Classification Factor (LRFR) of the AASHTO (2011). The first stage is divided into two types of inspections. In the first place, it is an initial inspection to collect general information on a population of ten bridges, of which three bridges were chosen as a sample (Nicolás Dueñas, El Ejército and Corpac). Second, a routine inspection was performed on the sample bridges to determine the condition status of the components. Then, from the last inspection, the structural evaluation of the superstructure was developed through the LRFR methodology in the sample bridges. Finally, the results, analysis and proposals for improvements validated by expert judgments based on the experience of applying in the case study are presented. / Tesis