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The European railway network includes many steel bridges, both plate girder and truss girder, often dated back to the end of the 19th century. The assessment by the partial factor method according to Eurocodes often reveals insufficient reliability of these bridges. In particular, they often fail to satisfy the equilibrium limit state (EQU) when strong wind occurs simultaneously with an unloaded train crossing the bridge or in the strength limit state (STR) when the strong wind is combined with extreme traffic live load. To avoid unnecessary structural interventions and expensive traffic restrictions, eight representative types of these bridges are tested in the wind tunnel to refine force coefficients of wind pressure for the specific bridge shape and selected types of light-weight vehicles. The values of force coefficients based on wind tunnel tests correspond on average to 70-80 % of those determined according to EN 1991-1-4. Traffic flow records for three representative railway lines are then utilized to obtain distributions of weights and heights of light-weight trains, for low to high traffic intensity. Wind records covering around last 50 years are utilized to establish wind speed distributions characteristic for wind zones in the Czech Republic, thus representative for the Central European inland mild climate. Detailed probabilistic analysis of all cases demonstrates that reliability of these bridges is close to the target level specified for EQU assessment when the wind tunnel force coefficients are considered along with site-specific free-field wind and railway traffic records. It is shown that case-specific information may help to reduce numerous “hidden safeties” in reliability assessments, often included in the models for permanent actions and geometry, wind pressure, traffic load, and the combination of the last two.

<p>The paper describes the final results of the project focused on the assessment of the existing railway bridges with respect to the wind load and traffic load in both ultimate limit state and equilibrium limit state. The outcomes of the project are based on extensive wind tunnel testing. Detailed probabilistic and reliability study is presented in this contribution using the wind tunnel data, and available railway traffic and wind speed data for a given location. The main result is a set of reduction factors for wind forces acting on specific railway bridge types and rail vehicles and calibrated combination factors for simultaneous action of unloaded train and wind in equilibrium limit state.</p>

<p>The goal of this paper is to describe the deterioration progression through the lifetime of the West Seattle Bridge which led to its closure in March 2020 and to provide a summary of the rehabilitation and strengthening process. The main part of the paper focuses on the construction engineering phase of the rehabilitation and performed structural analysis. Detailed structural analysis was performed using advanced global shell element analysis model which was used to reveal the root causes of superstructure cracking and crack propagation in time. As a part of the construction engineering the superstructure was assessed in detail in all critical stages of strengthening and restrictive measures had to be taken to maintain sufficient level of safety during construction.</p>