Fatigue performance evaluation of steel arch bridge based on experimental tests in the light of increased operating loads

Abstract

The paper presents a case study of experimentally supported fatigue performance evaluation of over 22-year old composite (steel-concrete) arch bridge. The bridge is a landmark road structure crossing the Narew River in Ostrołęka in Poland. It’s main span is composed of through arch static system. The structure was designed to carry out the local town traffic. The bridge due to the emergency condition of the neighboring bridge located along national roadway was temporarily subjected to increased live loads. Thereby it became to play an important role in the transportation system of the whole region being intensively exploited by heavy vehicles in many cases neglecting compliance with restrictions for total weight of heavy trucks. Thus, taking into account limited load capacity and intensity of the traffic crossing the bridge, some doubts about the fatigue performance of bridge critical members were formulated. Fatigue performance evaluation of the steel superstructure was executed according to general assumptions of the Eurocodes and the European Recommendations for Estimation of Remaining Fatigue Life of Existing Steel Structures. Essential input data used for estimation of fatigue damage accumulation in critical bridge components as well as for prediction of residual lifetime of the whole structure was based on experimental vibration tests performed under operating loads.