Abstract
The paper proposes an accurate methodology to estimate remaining fatigue lives of riveted railway bridges. The proposed method mainly consists of measured stress histories, recently developed sequential law and fully known Wohler curve. Here, it is essential to use the fully known Wohler curve as the related fatigue curve. Therefore the technique, which utilizes to transfer the partially known Wohler curve to fully known curve, is also discussed under this paper. Since most of the bridges do not have past strain measurements, this method describes reasonably accurate procedure to obtain the past stress histories from present day measured stress histograms. Initially paper describes the proposed method for remaining fatigue life estimation. Secondly remaining fatigue life of an existing railway bridge is estimated by performing a case study. Case study describes the details of the considered railway bridge and the appraisals related to condition evaluation, FE analysis, material testing, experimental static and dynamic load testing. Then the remaining fatigue lives of each critical components of the bridge are obtained. Hence validity and merits of proposed method is confirmed by comparing the results with previous method-based fatigue lives.
Highlights
In past t w o decades, a significant amount of efforts have been directed towards the development of structuralhealthmonitoring and non-destructive assessment methods to manage civil structures more efficiently [1]
Real fatigue life due to same loading pattern is higher than the Miner's expectation for increasing type loads and it is lower than the Miner's expectation for decreasing type loads
A new damage indicator-based sequential law [8] wasoriginated to overcome this shortcoming of Miner's rule and it has been proved that sequential law gives more realistic results than Miner's rule w h e n material is subjected to variable amplitude loading
Summary
In past t w o decades, a significant amount of efforts have been directed towards the development of structuralhealthmonitoring and non-destructive assessment methods to manage civil structures more efficiently [1]. Experiences from engineering practices have indicated that fatigue analysis based on specification loads and distribution factors usually underestimates the remaining fatigue life of existing bridges by overestimating the live load stress ranges In this context fatigue evaluation based on field measured stress range histograms under actual traffic load proves to be a more accurate and efficient method for existing bridges [3,4]. Major objective of this paper is to check t h e significance a n d applicability of the sequential law to estimate the remaining fatigue life of a riveted railway bridge by proposinga new method based on measured stress histories, recently developed sequential law [8], and Wohler curve.
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