Estudio comparativo entre un diseño optimizado respecto a uno sin optimizar en puentes tipo losa de concreto armado usando el método del ancho equivalente de franjas del manual de puentes MTC 2018

Abstract

La presente investigación tiene como objetivo evaluar la diferencia entre un diseño optimizado respecto a uno sin optimizar en puentes tipo losa de concreto armado usando el método aproximado del ancho equivalente de franjas del manual de puentes MTC 2018. El desarrollo de la investigación comprende los siguientes procesos: primero, registro de las propiedades de los materiales, propiedades geométricas, cargas de diseño y metrado de cargas; segundo, determinación del ancho equivalente de franjas del manual de puentes MTC 2018 y predimensionamiento del peralte de la losa; tercero, desarrollo del diseño mediante optimización matemática compuesto a su vez por: la discretización de la longitud del puente, determinación de la función objetivo (función matemática principal que será optimizada, en nuestro estudio será el costo directo referencial) y sus subfunciones (peralte de la losa, volumen de concreto, peso del acero y área de encofrado), determinación de la variable (peralte de la losa) a ser optimizada, implementación y programación de los métodos matemáticos (paso constante, bisección y sección aurea) en el software informático Maple, y por último determinación del peralte óptimo de la losa. Cuarto, una vez determinado el peralte sin optimizar (predimensionado) y optimizado se procedió a la determinación del análisis estructural (fuerzas cortantes y momentos flectores) y diseño estructural (áreas de acero), con estos datos se hallaron los parámetros de la función objetivo (volumen de concreto, peso del acero, área de encofrado y el costo directo referencial), tanto para un diseño optimizado y sin optimizar. Quinto, del estudio realizado se obtuvo que la función objetivo de un diseño optimizado (por el método de la sección aurea) respecto a uno sin optimizar, para luces de 4.00m, 4.50m, 5.00m, 5.50m, 6.00m, 6.50m, 7.00m, 7.50m, 8.00m, 8.50m, 9.00m, 9.50m, 10.00m, 10.50m, 11.00m, 11.50m y 12.00m, resultan menores en 15.35% promedio. Finalmente, como aporte se tiene que el diseño con optimización propuesto es aplicativo en puentes tipo losa de concreto armado para longitudes de entre 4.00 metros y 12.00 metros, teniendo como objetivo principal el de minimizar costos.

The earthquake is a natural phenomenon that produces great destruction in populated areas where the knowledge of vibration control is insipient, disasters are dependent on their intensity and magnitude; Mitigating this effect in any structure is the field of action of Civil Engineering worldwide. Peru is part of the Pacific Ring of Fire, due to the subduction phenomenon between the Nazca and South American tectonic plates, it also presents seismicity due to cortical geological faults, for this reason, it is exposed to seismic movements that cause structural damage and loss of lives. In this thesis, the dynamic analysis time history “Fast non-linear” is used for the seismic controllers used (elastomeric isolator with lead core and viscous fluid dissipator), using the ETABS-2017 software to block “B” of the pavilion from the Faculty of Engineering and Architecture of the Andean University of Cusco (UAC), subjected to 7 real earthquakes, which occurred in places with the same seismic zone, which were duly scaled; Synthetic earthquakes with harmonic behavior and spectral accelerations of (Norma E.030 Diseño Sismorresistente, 2018) Seismic-resistant Design. The structure is dynamically analyzed in three conditions Fixed Base, Insulated Base and Insulated Base with Viscous Damping. For the analysis of the structure with a fixed base, (Norma E.030 Diseño Sismorresistente, 2018) is used, for the structure with an isolated base, (Norma E.031 Aislamiento Sismico, 2019)Seismic Isolation is used, and for the structure with an Insulated Base and Viscous Damping, is used as a complement (Norma UBC 97, 1997), with the objective of comparing the seismic response of the isolated base structure and the isolated base structure with viscous damper, with respect to the fixed base structure, determining its Natural period of vibration of the fixed base structure at 0.653s in the YY direction, for the isolated and isolated structure incorporated with viscous damping, a natural period of vibration of 2.89s was determined in the YY direction. The response of the structure in terms of shear forces is reduced for the structure with insulated base up to 82.97% in the “Y“ axis and 88.30% for the “X“ axis. For the insulated base structure incorporated with viscous damping in the base, it is reduced up to 82.88% in the “Y” axis and 88.39% in the “X” axis compared to the fixed base. The absolute displacement of the insulated base system increases by 1499.79% in the “X” axis and 1208.80% in the “Y” axis and in the structure with viscous damper insulators, it increases by 1546.31% in the “X” axis and 1120.61% on the “Y” axis with respect to the fixed base structure corresponding to the first mezzanine level. In relation to the relative displacements, the isolated base model decreases up to 80.76% in the “X” axis and 70.66% in the “Y” axis; and for the model with insulators incorporated with viscous damper, it decreases up to 81.11% on the “X” axis and 62.87% on the “Y” axis. Reaching the main conclusion that the best seismic response is the isolated base system without any complement.