The 9 th International Conference “ENVIRONMENTAL ENGINEERING” 22–23 May 2014, Vilnius, Lithuania SELECTED PAPERS eISSN 2029-7092 / eISBN 978-609-457-640-9 Available online at http://enviro.vgtu.lt Corresponding author: Darius Bacinskas. E-mail address: Darius.Bacinskas@vgtu.lt http://dx.doi.org/10.3846/enviro.2014.142 © 2014 The Authors. Published by VGTU Press. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Section: Roads and Railways Field load testing and structural evaluation of steel truss footbridge Darius Bacinskas a , Zenonas Kamaitis a , Donatas Jatulis a , Arturas Kilikevicius b , Eugenijus Gudonis a , Giedrius Danielius a , Vytautas Tamulenas a , Deividas Rumsys a a Department of Bridges and Special Structures, Vilnius Gediminas Technical University, Sauletekio ave. 11, LT-10223 Vilnius, Lithuania b Department of Machine Building, Vilnius Gediminas Technical University, J. Basanavičiaus str. 28, LT-03224 Vilnius, Lithuania Abstract The paper presents the main results obtained during a field load testing conducted on a recently built steel footbridge spanning the new 6 lanes of Western bypass highway in City Vilnius. The footbridge is a single span 48,8 m long and 4,0 m width structure composed of two identical steel trusses. The footbridge was subject to static and dynamic tests as well as theoretical calculations in order to perform an evaluation of the static behaviour of the new footbridge and to identify its dynamic characteristics. The results of the tests were used to validate the FE modelling. A comparison of the measured and analytical results for both static and dynamic tests is presented. Results of investigation are also compared to the provisions of LST EN standards. Keywords: steel footbridge; field-load testing; modal characteristics; FE analysis; comfort criteria. 1. Introduction In the last year’s design of modern footbridges are focused towards greater and lighter spans having increased flexibility and sensitivity to ambient actions. Full-scale load tests along with numerical simulation allow determining the realistic bridge response to static and dynamic human induced loading and to verify the assumptions made in the design of pedestrian structures. Footbridges are designed to ensure the safety and serviceability of structures and safety and comfort for pedestrians. During the last few decades numerous investigations have been performed [1–3] and field load testing and monitoring systems of footbridges are employed [4], [5] in order to validate design conceptions, to evaluate condition state and overall performance of structures. The problems related to serviceability failures and sometimes to ultimate limit states of pedestrian bridges are reported in the literature [5–8]. Lithuanian standards LST EN 1991-2 [9] and LST-EN 1990 [10] which are based on Eurocodes provisions present the recommendations in terms of resonant frequencies and acceptable accelerations based on the response for a single pedestrian only. Although, the models for human-induced dynamic loading for different traffic scenarios as well as limiting values of footbridge vibrations are still under development. The aim of this investigation was to establish more realistic understanding of the behaviour of steel truss footbridge. Static and dynamic loading as well as FE modeling was performed. The main results of this investigation are presented in the paper. 2. Truss steel footbridge 2.1. Description of the structure The bridge under consideration is a part of Vilnius Western bypass and was constructed in 2013. A superstructure shown in Fig. 1 is widely used in Lithuanian roads and railways. Two main steel trusses of a rectangular configuration is 48,8 m long and 4,0 m width. At the ends of the span the superstructure is supported by elastomeric bearings based on reinforced concrete abutments and corresponds to simply supported beam. The depth-to-span ratio of truss span is 1/7–1/8. The typical cross-sections of footbridge generally consist of tubular hollow section members. Orthotropic bridge deck comprises a