Abstract
The comprehensive study on the structural behaviour of underslung girder bridge is examined in this study through both numerical modelling and experimental 3D model tests. The structural design of steel bridges in many cases is governed by their ability to withstand asymmetric loading conditions. Three different symmetric and asymmetric load cases were investigated to capture the deformational and flexural response of the main girder. It was found that under distributed load the structural response of underslung girder bridge was similar to beam-column with intermediate elastic supports. The numerical model was validated against experimental data with good agreement perceived, allowing an extensive parametric study to be performed. The observed influence of initial geometric imperfections and nonlinearities are discussed. It was found that symmetric load governs the ultimate limit state. However, the asymmetric one takes over in the case of serviceability. Finally, the study presented herein summarises experimental investigations, numerical simulations and design proposals obtained through the recent few years research program, carried on to deepen the knowledge on the structural behaviour of underslung girder bridges.
Highlights
Underslung girder, like their counterparts, cable-stayed bridges couple functionality with aesthetics of architectural design that are often used as a symbol of exclusivity for the city or even for the region where they are situated
The assumptions used for the mathematical model coincide with the requirements for the Geometrically Nonlinear Analysis with Imperfections (GNIA), which was used for the finite element (FE) simulations
The experimental model was tested under a combination of symmetric dead and asymmetric live load to evaluate the structural behaviour of the underslung girder bridge using asymmetric engineering load
Summary
Underslung girder, like their counterparts, cable-stayed bridges couple functionality with aesthetics of architectural design that are often used as a symbol of exclusivity for the city or even for the region where they are situated. Since stability tends to be one of the main issues in stayed structures design, Saito and Wadee (2008) presented their study on the postbuckling behaviour of steel stayed columns They found that the post-buckling behaviour is strongly dependent on the level of the initial pre-stress. Earlier Saito and Wadee (2009) examined the buckling behaviour of steel stayed columns with geometrical imperfections, and stress limitation relating to possible material failure Their studies tend to show that such structures are the most sensitive to imperfections at a prestressed level that yields the highest critical load. This study aims at providing a broader grasp on the flexural and deformational behaviour of UGB and its design It presents the numerical results obtained through nonlinear analysis using initially imperfect and elastically supported beam-column mathematical model and two amplification factor techniques covering the second order effects for the first order calculations. Research draws some interesting conclusions on the application of design amplification methodologies
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