Examinando por Materia "AASHTO"

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    Comparación del método AASTHO y el SETRA en Evaluación del desempeño dinámico en pasarelas ante vibraciones inducidas por peatones
    (Universidad EAFIT, 2022) Guerrero Lobo, José Antonio; Garza Vázquez, Luis
    This deepening work is focused on determining if the methodology proposed by "AMERICAN ASSOCIATION OF STATE HIGHWAY AND TRANSPORTATION OFFICIALS LRFD GUIDE SPECIFICATIONS FOR THE DESING OF PEDESTRIAN BRIGDES" AASTHO,(2012), which implements a derivation of the equations proposed by Allen & Murray (1993), to be used when the vertical frequency does not exceed the lower range of 3Hz, are suitable for designing walkways that have acceptable levels of comfort against vibrations induced by pedestrians. It will be verified by comparing the results between the AASTHO methodology, (2012) and that of the Service d'études sur les transports, les routes et leurs aménagements Setra, (2006). The methodology of the work was based on the analytical analysis with verification through mathematical models and two real cases. Five families of footbridges were defined with typologies of structures commonly used in Colombia and that present frequencies in the zone of risk due to resonance. For each family, three specimens of the same structure were defined but varying the free length between supports with an average length of 30 ml, in this way it was possible to obtain variations in the natural frequencies of the families that allowed observing their effect on the dynamic response. Subsequently, the verifications required by the AASTHO methodology (2012) were made and the dynamic performance evaluation of the Setra (2006) for three pedestrian densities was carried out, performing a total of 45 analyses. From the results obtained from the analysis of the gateway families, it was determined that; in some cases, even meeting the requirements of the AASTHO method, (2012) the walkways had minimal or unacceptable comfort levels based on the Setra method, for which the AASTHO method is not reliable for the design of walkways against vibrations induced by pedestrians . Additionally, the evaluation of the dynamic performance against vibrations was carried out in two real cases; one that has adequate levels of comfort, another that presented excessive vibrations and had to be reinforced with an intermediate support. In the first real case, Gateway of the EAFIT university, it was determined that; did not comply with the lower limit of the AASTHO,(2012) of 3hz since its fundamental frequency is 2.32 Hz, for this reason it was evaluated with the equation (6-1) of the AASTO,(2012), obtaining an incongruous value since which gave negative frequency values, then equation (6-2) of the AASTO (2012) was evaluated, obtaining that it meets the requirement and should not present vibration problems. Subsequently, a dynamic performance analysis was carried out following the Setra methodology, concluding that the comfort levels are acceptable. In this case, both the AASTO (2012) and Setra (2006) methodology coincide with the real behavior of the structure. In the second real case, Pan de Azúcar metal footbridge, it was determined that; did not meet the lower limit of the AASTO, (2012) of 3hz since its fundamental frequency is 2.63 Hz, it was evaluated with the equations (6-1), and (6-2) of the AASTO, (2012 ), complying in both cases for which it meets the requirement and should not present vibration problems. Subsequently, a dynamic performance analysis was carried out following the Setra methodology, concluding that the comfort levels are unacceptable. In this case, it is evident that even meeting the AASTHO requirements, the Setra method predicted that the comfort levels will not be adequate, a behavior that coincides with the real response of the structure during its operation, which had to be reinforced due to problems. of vibrations. It was concluded in this investigation that the equations (6-1) and (6-2), of the AASTO, (2012), are not reliable to design footbridges that have acceptable levels of comfort before vibrations induced by pedestrians. Keywords: dynamic walkway performance, crowd-induced vibrations, pedestrian bridge vibrations, lateral vibrations, human-structure interaction, Setra, AASHTO.