Loads, Capacity & Resistance
This Work Package is working with the load assessment and resistance assessment of existing railway bridges. For the load assessment various loads on railway bridges both at present and in the foreseeable future are studied. There are wide differences in the effects on a bridge from a freight train with heavy axle loads and a high-speed passenger train and this is a part of the study. The main effort is concentrated on the train load and the dynamic effect.The resistance assessment is focusing on the typical European railway bridge types and critical sections, as identified in WP 1. This includes steel or other metallic, concrete and masonry bridges. One of the important issues for the resistance assessment is also to include the actual condition of the structure.
The main objective is to establish a "state of the art" practice for assessing the load and resistance of existing railway bridges in Europeand develop a guideline for best practice of load and resistance assessment including the future "state of the art". The latter includes for example the development of methods to assess the actual load on a bridge and to assess the resistance taking into account the measures for the actual condition of the bridge(s), which has been identified in WP 3. Furthermore the results of the monitoring developed in WP 5 are to be considered in a similar way.
Description of work
WP 4 is organized in five sub-groups:
- Loading group
- Safety and probabilistic modelling group
- Concrete bridges group
- Metal bridges group
- Masonry arch bridges group
The load group will provide new knowledge regarding, dynamics, load distibution and fatigue. Further probabilistic methods for assessing the actual load on the bridges will be developed. Advanced non-linear resistance assessment is also one of the major issues for WP 4, mainly considering concrete bridges. Also the special aspects for the safety format to be taken into account when using non-linear analysis and fatigue are addressed in WP 4. The research work considering metallic bridges is concentrated on one part considering the material properties for old metallic bridges in Europeand the other major part on advanced analysis of riveted metal bridges.
For masonry arch bridges the research work includes cyclic load tests on short span brickwork. The reason is that recent research work has indicated that cyclic loading of old masonry arch bridges are critical and can be limiting a resistance assessment. Another important issue for masonry arch bridges is the soil-structure interaction which is difficult to include in a resistance assessment. Research is being carried out in order to supply a need for such a tool.
The primary outcome of WP 4 is a Guideline for Load and Resistance Assessment of Existing Railway Bridges. It is aimed to deliver a report which is of practical use for a structural engineer, familiar with structural assessments of railway bridges. The outcome of the research activities will be included in this guideline and it will also be reported separately in background documents.