A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Strengthening of I-girder bridges : Fatigue endurance
Structures have always been subjected to the detrimental consequences of the fatigue phenomenon. The consequences due to this damaging effects leads to crack initiation and the ultimate result being complete failure. Fatigue appears on structures that has to endure fluctuating loads over a long period. The crack initiation occurs irregular geometries such as in the vicinity of welds and bolts. A structure that suffers a lot due to fatigue are road bridges. In this thesis the structure under investigation is a composite bridge with a concrete slab on top of two I-girders. The recommended lifetime of road bridges in the Eurocode is 100 years.Bridges are exposed to daily and yearly traffic loads. Also the amount of traffic and therefore the total weight shows a continuously increasing trend over the years. This tendency is under no circumstances expected to stagnate. Eurocode has based its approach to verification of fatigue on applying adversely combined traffic loads, in both directions, on the bridge. In the procedure of double I-girder composite bridges verification there is an uneven distribution of the vehicle loads and the stresses, as the bridge is behaving as an open cross-section. The concrete slab is the only apparent part that is transferring the vehicle loads to the other girder and gives therefore an unequal distribution of the loads.Because of this uneven load distribution there appears to exist some potential in finding a means to strengthen the bridge by ways of making it work as a semi-closed cross-section. This will enhance the load distribution over to the non-stressed girder. In this thesis the focus was set on the stress relation between the center web stiffener to the lower flange, with and without the strengthening, for a real case section. Assessment were done for case studies where the Rokån bridge as well as four arbitrary cross-sections were investigated in search of retrieving an increased understanding of the mechanism of stress distribution.The strengthening approach is to introduce a ...
Strengthening of I-girder bridges : Fatigue endurance
Structures have always been subjected to the detrimental consequences of the fatigue phenomenon. The consequences due to this damaging effects leads to crack initiation and the ultimate result being complete failure. Fatigue appears on structures that has to endure fluctuating loads over a long period. The crack initiation occurs irregular geometries such as in the vicinity of welds and bolts. A structure that suffers a lot due to fatigue are road bridges. In this thesis the structure under investigation is a composite bridge with a concrete slab on top of two I-girders. The recommended lifetime of road bridges in the Eurocode is 100 years.Bridges are exposed to daily and yearly traffic loads. Also the amount of traffic and therefore the total weight shows a continuously increasing trend over the years. This tendency is under no circumstances expected to stagnate. Eurocode has based its approach to verification of fatigue on applying adversely combined traffic loads, in both directions, on the bridge. In the procedure of double I-girder composite bridges verification there is an uneven distribution of the vehicle loads and the stresses, as the bridge is behaving as an open cross-section. The concrete slab is the only apparent part that is transferring the vehicle loads to the other girder and gives therefore an unequal distribution of the loads.Because of this uneven load distribution there appears to exist some potential in finding a means to strengthen the bridge by ways of making it work as a semi-closed cross-section. This will enhance the load distribution over to the non-stressed girder. In this thesis the focus was set on the stress relation between the center web stiffener to the lower flange, with and without the strengthening, for a real case section. Assessment were done for case studies where the Rokån bridge as well as four arbitrary cross-sections were investigated in search of retrieving an increased understanding of the mechanism of stress distribution.The strengthening approach is to introduce a ...
Strengthening of I-girder bridges : Fatigue endurance
Edström, Olle (author)
2016-01-01
Theses
Electronic Resource
English
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