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Bridge Management Objectives and Methodologies
Published in J.E. Harding, G.E.R. Parke, M.J. Ryall, Bridge Management 3, 2014
In [5], it is calculated, using the FEM of analysis and the model illustrated in Fig. 2 together with a traffic flow model based on the traffic survey carried out in HEPC, that the fatigue life of the lower flange connected to the lower end of a vertical stiffener by welding at the mid-cross section of the outer main girder is about 70-90 years. The factor of 1.33 in this figure is for modifying the numerical results from the FEM analysis compared with the measured stresses in a test using an actual bridge. A concept of a management period for maintenance is introduced instead of the service life of steel bridges in urban elevated highways in order to investigate the total cost of steel bridges. The management period for maintenance is set at 90 years on the basis of the fatigue life of the lower flange plate of the plate girder bridge.
Enhancement of the life-cycle performance of bridges using high-strength steel
Published in Structure and Infrastructure Engineering, 2020
Melaku Seyoum Lemma, Helena Gervásio, Jose Oliveira Pedro, Constança Rigueiro, Luis Simões da Silva
However, bridge superstructures are usually welded structures and, in this case, the effects of notches, welded defects and local corrosion reduce the fatigue strength, by reducing the number of cycles needed to initiate a fatigue crack. That is, the largest part of the fatigue life comes then from the crack propagation period. Consequently, for samples with the same defects, the fatigue strength of welded HSS structures is not higher than those of mild steel. That is one of the reasons why HSS have limited use in applications where fatigue is a critical issue, such as highway and railway bridge superstructures. In fact, fatigue presents a major constraint to the design of plate girder bridge superstructures with transverse stiffeners, namely, on span sections, due to allowable plate stresses range near the welded joints.