| Summary: |
This research project aims the development and application of procedures for evaluation of the structural integrity of metallic railway bridges, taking in consideration the fatigue damage that can be induced by the large number of loading cycles applied during their life time.
The project will be conducted by a team of Structural Engineers of FEUP, in collaboration with colleagues from the Mechanical Engineering Department with great expertise in the field of fatigue. The research work will be focused on an old railway bridge of REFER, comprising the following main vectors:
a) Systematization of the most relevant and updated scientific and technical information, as well as of data and results concerning fatigue studies in metallic bridges with riveted or bolted joints;
b) Characterization of the historic evolution of the railway traffic loads during the bridge life time, and subsequent assumption of realistic load scenarios for the development of numerical simulations of the structural behaviour;
c) Assessment of the geometrical and mechanical characteristics of the bridge and development of 2D and 3D finite element models for characterization of the static and dynamic structural behaviour and identification of critical zones from fatigue point of view. Evaluation of the structural response of the bridge induced by railway traffic loads corresponding to the load scenarios used to appropriately characterize the past and future traffic flow on the bridge;
d) Temporary monitoring of the static and dynamic structural behaviour of the bridge, so as to experimentally validate the numerical simulations by correlating measured and calculated values. Performance of an ambient vibration test and a static load test, measuring structural deformations, rotations and displacements under thermal and current railway loads;
e) Use of all the relevant parameters of the bridge (static and dynamic), identified and quantified during the monitoring phase, in order to introduce a  |
Summary
This research project aims the development and application of procedures for evaluation of the structural integrity of metallic railway bridges, taking in consideration the fatigue damage that can be induced by the large number of loading cycles applied during their life time.
The project will be conducted by a team of Structural Engineers of FEUP, in collaboration with colleagues from the Mechanical Engineering Department with great expertise in the field of fatigue. The research work will be focused on an old railway bridge of REFER, comprising the following main vectors:
a) Systematization of the most relevant and updated scientific and technical information, as well as of data and results concerning fatigue studies in metallic bridges with riveted or bolted joints;
b) Characterization of the historic evolution of the railway traffic loads during the bridge life time, and subsequent assumption of realistic load scenarios for the development of numerical simulations of the structural behaviour;
c) Assessment of the geometrical and mechanical characteristics of the bridge and development of 2D and 3D finite element models for characterization of the static and dynamic structural behaviour and identification of critical zones from fatigue point of view. Evaluation of the structural response of the bridge induced by railway traffic loads corresponding to the load scenarios used to appropriately characterize the past and future traffic flow on the bridge;
d) Temporary monitoring of the static and dynamic structural behaviour of the bridge, so as to experimentally validate the numerical simulations by correlating measured and calculated values. Performance of an ambient vibration test and a static load test, measuring structural deformations, rotations and displacements under thermal and current railway loads;
e) Use of all the relevant parameters of the bridge (static and dynamic), identified and quantified during the monitoring phase, in order to introduce appropriate modifications in the numerical modelling, so that it can simulate with accuracy the measured structural behaviour.
f) Analysis of the structural elements, nodes and joints, where most probably fatigue damage will occur, taking into account the level of induced stresses, and construction of loading histograms on the basis of statistical assessment of the loading cycles;
g) Characterization of material mechanical properties, in terms of resistance and tenacity, and performance of fatigue tests of structural elements and joints.
h) Evaluation of the bridge's residual life time, based on the loading histograms obtained, the mechanical structural properties and the content of EC3, AASHTO and BS5400 standards concerning the analysis of fatigue.
i) Development of Guidelines for the evaluation of the residual life of metallic railway bridges, that can be included in Manuals for Inspection and Maintenance of Metallic Bridges. |
| Results: |
In 1997, the Portuguese Railway Network comprehended about 787 metallic bridges from a total of 2009 railway bridges. The total length of the metallic bridges was 23.4km, while the total length of the remaining concrete and masonry bridges was inferior to 15km.
Beyond that, it must be noted that more than 16km of those metallic railway bridges were then already older than 60 years, being regularly submitted to load cycles than can induce fatigue damage.
These figures clearly show the social and economical importance of developing an appropriate and reliable inspection and maintenance of old metallic railway bridges, allowing to guarantee acceptable safety levels.
Therefore, the present project will certainly have a very positive repercussion in this field, by developing an experimentally and numerically tested methodology for the assessment of the structural integrity, establishing general Guidelines for the evaluation of the fatigue residual life of metallic railway bridges, which can be included in Manuals for Inspection and Maintenance of Metallic Bridges.
Moreover, the project will lead to the obtainment, at FEUP, of a solid scientific competence in the area of Fatigue in Old Metallic Railway Bridges, as well as the development of new Ph.D and M.Sc. Research works (on the topics of Structural Health Monitoring, Fatigue Damage Assessment, Output-Only Modal Identification and Measurement of Dynamic Strains).
The expertise achieved in this area will certainly allow to extend subsequently the research work to neighbour fields, related with the assessment of fatigue problems in new high speed railway bridges (where dynamic problems associated to resonant behaviour can play an important role) or to metallic roadway bridges. |