Discussion of "Fatigue Performance of Stringer-to-Floor-Beam Connections in Riveted Railway Bridges" by Mohammad AI-Emrani

The rivet failures discussed by the author are a significant maintenance problem in riveted railway bridges. Although railway bridge floor systems are typically designed as simple-span stringers supported by floorbeams, current design practices have reduced the frequency of failures in stringer-to-floorbeam connections that are due to continuity. The additional flexibility provided by an increased gauge distance in the legs of the connection angles attached to the floorbeam has reduced the live load stress in the fasteners through the floorbeam and the fillets of the connection angles. During the past 40 years, the use of highstrength bolts for field connections has significantly increased the resistance to tension in the fasteners. However, most railway truss spans in North America were erected before these practices became the normal ones.