Numerical modelling and vibration serviceability assessment of a steel footbridge with a significant 3D dynamic behaviour

Abstract

This paper focuses on the vibration serviceability assessment and numerical modelling of an existing steel truss footbridge located in the outskirts of Castellón, Spain. The footbridge is rather slender and composed by a main span and two access ramps supported on three 4-arm piers of different heights. Due to the connection between the main span and the ramps at the top of the tall piers, longitudinal and lateral bending/torsion natural coupled modes of vibration coexist at low frequencies, with a relevant contribution of the piers and access ramps deformation. This leads to a significant three-dimensional and rather complex dynamic response under service conditions. With the aim of characterising the structural dynamic properties and assessing the level of vibrations induced by crossing pedestrians, two in-situ experimental test programmes are conducted. On the one hand, the structural response is measured during several hammer tests and the modal properties are identified and used to update a detailed 3D numerical model by means of a Genetic Algorithm. Due to the lack of information regarding the detailing of the piers foundations, two alternative models are analysed. The relevance of the pier-foundation system rotational stiffness is highlighted for the particular configuration. On the other hand, the footbridge main span response is recorded under different pedestrian activities: walking, running and vandal simulated actions. Finally, the vibration serviceability of the structure is assessed based on current codes and regulations.

Special issue: Advanced mathematical modeling in mechanical engineering

“…Few more articles are dedicated to specific construction engineering problems. 8,9 Zoric and Trajkovic-Milenkovic 8 develop a semi-analytical mathematical model for solving elastoplastic deflection of prismatic fixed-end beams with circular cross-sections loaded by lateral displacement at one end of the beam, suitable for different engineering applications. Homogenous and isotropic beams with bilinear elastoplastic strain hardening behavior are covered in the proposed solution.…”

“…The proposed semianalytical solution is validated by the finite element analysis and experimental results available in the literature. The specific problem of the vibration serviceability assessment and numerical modeling of an existing steel truss footbridge is presented in the article by Roda-Casanova et al 9 The described complex dynamic problem of this engineering construction is researched experimentally and modeled mathematically. By mathematically describing the experiments and developing a detailed 3D numerical model adjusted by means of a genetic algorithm, the vibration serviceability of the structure is assessed based on current codes and regulations.…”