New launching method for steel bridges based on a self-supporting deck system: FEM and DOE analyses

Abstract

This paper studies a new launching method for steel bridges based on a self-supporting deck system. This new and patent-protected procedure is able to launch bridges of a span length up to 150 m, in an economical and sustainable way. The use of the last span segments to reinforce the critical sections during launching replaces other conventional temporary means applied nowadays. The main objective of this research paper is to numerically analyse the best double deck configuration as well as to define an approach to stiffener distribution in order to avoid the patch loading phenomenon in the slender webs. With this in mind, the pre-design of a triangular cell along the low flange of each web is presented. A three dimensional finite element model (FEM) is built and the design of experiments technique (DOE) is applied to obtain the best bridge configuration. This new construction method can be used together with a continuous launching system in order to increase the velocity of the whole operation and to improve safety during launching. Very good results have been obtained, in terms of deflection, patch loading resistance and vertical load on the pushing device. The comparison with other different construction systems and the application to a real case allows us to ensure the viability of the method described.

Pandeo crítico de vigas esbeltas con rigidizadores tipo delta diseñadas con AASHTO sometidas a cargas concentradas

“…Para finalizar, vale la pena destacar que soldar dos láminas de acero para generar el rigidizador delta aumenta los costos del material y del proceso de manufactura asociados a la fabricación de estas vigas. En la práctica, Navarro-Manso et al [8], [9] utilizaron rigidizadores tipo delta colocados en una posición d/hw0,10. Además, un rigidizador colocado a una distancia d/hw= 0,45 aumentaría considerablemente tanto el peso de la estructura como los costos de material.…”

“…Navarro-Manso et al [8], [9] desarrollaron un nuevo método de lanzamiento de puentes, el cual es una forma económica y efectiva para erigir estas estructuras; sin embargo, encontraron algunos inconvenientes durante el lanzamiento, uno de estos es el fenómeno asociado con las cargas concentradas sobre las aletas comprimidas de las vigas en I que forman parte de los módulos lanzados, que puede inducir a inestabilidad localizada en las almas. Este efecto ha sido ampliamente estudiado; algunos autores han empleado rigidizadores longitudinales para aumentar la resistencia última a cargas concentradas y evitar un posible aumento en el espesor del alma.…”

“…En el método propuesto por Navarro-Manso et al [8], [9] se utilizan aletas delta para mejorar la rigidez lateral y la resistencia a la flexión de la estructura. Estas aletas consisten en 2 placas soldadas a la aleta comprimida y al alma de la viga en la porción cercana a dicha aleta (ver figura 1).…”

Improved design of transversally stiffened steel plate girders subjected to patch loading

“…Engineering judgement suggests that the smaller the distance "a", the higher the buckling strength of the web plate. However, the EN1993-1-5 [1] design provision shows that for spacing less than a/l y =1, the predicted strength of the web reduces with the reduction of the spacing between vertical stiffeners (a), as shown in The ultimate strength of steel plate girders subjected to patch loading has been studied in depth for members with largely spaced stiffeners (a/l y >1.0) through mechanical models [2][3], critical buckling loads approaches [4][5], bending and shear interaction schemes [6][7][8] and more recently, bridge launching Structural Health Monitoring (SHM) applications have been implemented [9][10]. The case of closely spaced stiffeners has been studied to a lesser extent both experimentally and numerically, except for the work reported in References [11,13] and the design formulation summarized in [12].…”

Patch loading resistance of steel plate girders stiffened with triangular cell flanges

“…Ripa-Alonso [4] investigated the influence of triangular cell flanges on both critical buckling capacity and resistance of steel plate girders subject to patch loading. Navarro-Manso [5] developed a steel bridge launching system based on a self-supporting double deck, in which the bottom flanges were stiffened with a triangular cell to withstand the concentrated load reactions in the supports. Navarro-Manso et al [6,7] performed a series of numerical studies using design of experimental techniques to optimize the size and type (symmetric and asymmetric) of the triangular cells with respect to patch loading resistance.…”