Bridge Overhang Slabs with Edge Beams
LCCA and Structural Analysis for the Development of New Concepts
Time: Fri 2020-12-18 12.00
Location: Videolänk (Zoom) https://kth-se.zoom.us/j/65730184104, Du som saknar dator /datorvana kontakta Raid Karoumi email@example.com / Use the e-mail address if you need technical assistance., Stockholm (English)
Subject area: Civil and Architectural Engineering, Structural Engineering and Bridges
Doctoral student: José Javier Veganzones Muñoz , Bro- och stålbyggnad
Opponent: Professor Rui Vaz Rodrigues, Department of Civil Engineering and Architecture (DECivil), Technical University of Lisbon
Supervisor: Docent Costin Pacoste, Bro- och stålbyggnad; Professor Raid Karoumi, Bro- och stålbyggnad, Järnvägsgruppen, JVG, Byggkonstruktion; Dr Lars Pettersson, Bro- och stålbyggnad
Bridge edge beams are associated with high life-cycle costs because of the need of maintenance, which also causes traffic disturbances. For this reason, the Swedish Transport Administration started a project to find better solutions. One of the proposals was a design without edge beam. However, the edge beam contributesto the load distribution and its removal would imply a loss of robustness, especially in bridges with overhang slabs. The efficiency of this effect depends onthe width of the overhang slab. Moreover, the width of the slab in itself, even inthe absence of an edge beam, may influence the load capacity of the structure. These aspects are paramount for the performance of tests that study the shear capacity of overhang slabs and assess design methods.
The aim of this thesis is to contribute to the development of functional edge beam solutions in terms of cost and investigate the structural behavior of bridge overhang slabs with edge beams. A life-cycle cost analysis was the method to evaluate and identify edge beam alternatives that could qualify for further studies, including the use of stainless steel. Non-linear FE-analyses validated from experimental tests were used to investigate the influence of this member and the width of the overhang slab on the structural behavior under concentrated loads. Recommendations for minimal widths that ensure full load capacity of experimental specimens and an assessment of the existing calculation methods with special emphasis on the effective width were also studied.
The outcome led to the implementation of new edge beam solutions. The results showed that the influence of the edge beam is not only quantitative due to its load-carrying function but also qualitative as it may affect the failure mode. The load capacity increased with the width until a threshold was reached. The mechanisms behind were the increase of shear capacity and the distribution of the forces sideways, with an eventual redistribution. Recommendations for minimal widths that ensure full capacity were presented for its consideration in the design of experimental tests, with or without edge beams. Effective widths are practical for a preliminary design but may lead to unreliable estimates. Modified approaches given the control section and the presence of an edge beam were proposed.