FATIGUE ANALYSIS OF RIVETED CONNECTIONS IN STEEL BRIDGES

Abstract

There are numerous bridges across India which were built about 100 years ago. A large proportion of these bridges are made of steel, relatively old, past their design life. They are subjected to much larger loads running on them than that had been considered in their design. Moreover, fatigue which is an important factor for failure of steel bridges was not popular during the design of these bridges. Fatigue is a problem where vehicular live load forms major part of total loading. In such a scenario, the assessment of residual fatigue life of steel bridges becomes an important issue. Ir There has been a lot of research in this filed. But none of the methods suggested are fool proof and the fatigue life assessed using these methods has often been found to be unreliable. Most of the theories ask for assumptions to be made regarding certain things like material properties, joint rigidities, current health of the bridge etc. The assumed presence of fatigue cracks and the fear of brittle fracture are often unjustified. Hence a more sophisticated and reliable procedure needs to be developed for the assessment of residual fatigue life of steel bridges. Stringer-to-cross-girder connections in riveted bridges have been found to be susceptible to fatigue damage. Due to multiple cycles of loading on the stringers, these connections are one of the most fatigue critical connections in steel bridges. It is a well-documented fact through experiments carried out on riveted connections that the clamping force in a rivet plays an important role in its fatigue behaviour. An effort has been made to model the stringer-to-cross-girder connection using finite element method in ABAQUS by incorporating the detailed local geometry of the connection. The fatigue life of the connection is evaluated using the S-N curve and Palmgren-Miner linear damage hypothesis. The effect of clamping force of the rivet on the fatigue life of the connection is studied.