Reliability-based structural assessment of a historical steel railway bridge

<p>In this paper, a simplified probabilistic analysis approach is presented. The Barqueiro Bridge, a four- span riveted iron bridge located in Galicia, Spain, is selected as a case study. This bridge is placed in an environment with high humidity and salinity which could potentially induce severe damages to the structure. These damages introduce considerable uncertainty in the structural parameters that should be used in reliability-based assessment procedures for verifying current safety conditions. To alleviate this issue, non-destructive experimental testing is used which also helps during numerical modeling. Model uncertain parameters are described through adequate probability distributions and then grouped by using two different strategies; based on structural element type and on stress level. According to this strategy, the limit state of interest is analyzed to verify the probability of failure and the reliability index of the structure.</p>

Equivalent nosing force for a steel railway bridge based on in situ measurements

<p>The weight and design speed of the railway vehicles increases in time. As a result, the values of design loads grow up. In old Bulgarian standard [1] the equivalent nosing force is prescribed as 60kN. In the present EN1991-2 [2] this value is 100kN. Meanwhile, a significant part of the very old bridges is not designed for nosing forces. In cases of long span between cross girders of the “open type” deck and lack of nosing braces, the load bearing capacity of longitudinal girders, concerning out of plane bending moments due to nosing forces, is insufficient. To investigate the value of equivalent nosing force are provided “in situ” measurements on the longitudinal girders of “open type” deck of a steel riveted railway bridge in exploitation in the Republic of Bulgaria. The strains and horizontal linear deformations are measured in the midspan of the longitudinal beams for real trains. The equivalent nosing force is calculated using developed procedures.</p>

The Function of A Set-Aside Railway Bridge in Connecting Urban Habitats for Animals: A Case Study

As elements of green infrastructure, railway embankments are important corridors in urban environments connecting otherwise isolated habitat fragments. They are interrupted when railways cross major roads. It is not known whether dispersing animals use railway bridges to cross roads. We examined the function of a set-aside iron-steel railway bridge crossing a 12 m wide road with high traffic density in Basel (Switzerland) for dispersing animals. We installed drift fences with traps on a single-track, 32 m long and 6 m wide railway bridge with a simple gravel bed, and collected animals daily for 9 months. We captured more than 1200 animals crossing the bridge: small mammals, reptiles and amphibians as well as numerous invertebrates including snails, woodlice, spiders, harvestmen, millipedes, carabids, rove beetles and ants. For some animals it is likely that the gravel bed, at least temporarily, serves as a habitat. Many animals, however, were apparently dispersing, using the bridge to cross the busy road. We found season- and daytime-dependent differences in the frequency the bridge was used. Our findings indicate an important function of a set-aside railway bridges for connecting urban habitats. As most animal dispersal was recorded during the night, railway bridges with no (or little) traffic during the night may also contribute to animal dispersal. As important elements of green infrastructure, set-aside railway bridges should be considered in future urban planning.

Evaluation of Performance Indicator of Railway Bridges Using Updated Finite Element Model

Structural health monitoring (SHM) can provide information needed to make important decisions regarding the maintenance of bridge structures. However, the data collected from monitoring needs to be first translated into actionable, quantitative or qualitative based characteristics, that indicate the condition of a bridge. This paper presents a process of evaluation of such performance indicator in case of a steel railway bridge using the updated FE model and in-situ measurements of strains on selected stringers and floorbeams.