No abstract

No abstract

No abstract

Robustness evaluation of bridges within a risk-based framework requires estimation of the probability of occurrence of different hazards followed by an assessment of the vulnerability of the bridge with respect to those hazards, as well as quantification of the consequences of potential failure. The first part of the paper deals with a statistical analysis of past metallic bridge failures which can aid towards identifying the principal hazards affecting the bridges and their associated vulnerability. The results show that natural hazards, design errors and limited knowledge are amongst the most commonly encountered causes of collapse in metallic bridges, followed by accidents and human error aspects other than in design. When analysed chronologically, the data demonstrates a decreasing trend for collapses attributed to limited knowledge and an increasing trend in failures resulting from accidents and natural hazards. The paper continues by presenting a categorisation procedure through which consequences arising from potential bridge failures can be estimated. Associated models for quantifying their magnitude considering both spatial and temporal domains are highlighted. Finally, the predictive capability of the models is outlined through a case study.

As some of the older riveted railway bridges are close to or have even exceeded their theoretical fatigue lives, it is desirable to develop a comprehensive fatigue assessment methodology for fatigue-critical details. The aim of this study was to present damage and fatigue life estimates for the riveted connections of a typical riveted UK railway bridge through finite-element analyses. In particular, the effect of connection fixity and assumed fatigue detail classification, the effect of the simultaneous passage of two trains over the bridge, the effect of a reduced Young's modulus for the bridge material and the effect of dynamic amplification are studied under different loading scenarios. A historical load model was developed in order to represent bridge rail traffic between 1900 and 1970. The BS 5400 medium traffic trains were used to represent the bridge traffic from 1970 onwards. It was found that the connection damage is axle-dominated and is affected by the parameters mentioned above. The fully-fixed stringer-to-cross-girder connections were found to be the most fatigue-critical details. The damage accumulation rate was found to be small in the pre-1970 period under the historical load model but showed a considerable increase with the introduction of the BS 5400 trains (post-1970)

No abstract

No abstract

Weather-related disruption is a pressing issue for transport infrastructure in the UK, which is expected to aggravate due to climate change. Infrastructure managers, such as Network Rail, need to adapt to these changes, tackling the challenges brought about by wide-ranging uncertainties from various sources. This paper explores the relationship between climate change and bridge scour, identifying barriers to sustainable adaptation. Scour is the removal of riverbed material at bridge foundations due to hydraulic action and is the foremost cause of bridge failure in the UK and worldwide. A model is developed that simulates the causal chain from climate change to scour risk. This is applied to four case study bridges in Wales and the south-west of England, quantifying the effects of climate change and tracing key uncertainties in the process. Results show that the current scour risk models in Network Rail may be insensitive to increases in risk due to climate change. One way to tackle this may be to introduce models to assess absolute risk; current scour risk models are used only for the prioritisation of vulnerable sites.