ASSESSMENT OF RESIDUAL LIFE OF GIRDERS OF BRIDGE No

PREFACE
Whenever, a bridge is abandoned due to its weak substructure or some
other reasons before completing its codal life, it is important to know the residual
fatigue life of girders of its superstructure. If substantial life is still left, these
girders can be used on other routes. If the traffic density of such routes are
lower, these girders can be used for much more life span. Bridge No. 73 & 75,
known as Vasai creek bridges of Mumbai Central–Virar section of Mumbai
Division of W. Railway were abandoned due to their weak substructures after
completing about 66 years of service life and may have still, some useful life.
For estimation of the residual fatigue life of the girders by using S.N. curve
Approach, apart from the of stress- cycles (S.N.) curve of the material, the
stress-time history for the present day traffic passing over the girders is
essential, which is not possible to be obtained in case of above bridges, as the
bridges have been abandoned primarily due to weak sub–structure. For such
situation, the provisions of para. 9.2&9.3 of BS code 5400 part-10 are used for
assessment of residual fatigue life of these bridges. However, for more realistic
results, S.N. curve has been developed by fatigue testing of some samples
taken out from the existing girders. The S.N. curve, so developed, has been
used for assessing the residual life of the girders, by the method using damage
calculation.
For this work, a test team of S/Shri Ramji lal, SRE and S.K. Awasthi,
JRE-1 under the guidance of Sh. S.C.Gupta, Director/B&S/Testing was
constituted. The assessment of the residual fatigue life of the girders is done by
this team.
Fatigue testing of the samples was conducted by the staff of Fatigue
Testing Lab., under the guidance of Shri Mohan lal, SRE.
Contribution of all the team members in assessment of residual life
of the girders is highly appreciated. Guidance provided by Shri S.C. Gupta, to
the team members was worth appreciating, and sincerely acknowledged.
This report is submitted herewith for further necessary action to Executive
Director ( Works), Railway Board, New Delhi.
2
( LALLOO SINGH )
Executive Director/ B&S