Prestressed‐Concrete Railway‐Bridge Live‐Load Strains

Abstract

The paper presents the findings of field studies into impactive loading generated by trains on a prestressed‐concrete‐girder bridge. The studies were conducted on Denison Creek bridge, in Central Queensland, Australia, which comprises simply supported spans of varying length and carries a single ballasted track of continuously welded rail on prestressed concrete sleepers. Bridge traffic is almost exclusively heavy‐haul coal trains. Various defects were cut into one rail to model real defects such as wheel flats, wheel burns on rails, and broken or misaligned rails, Impacts from trains were measured via two independent strain‐gage systems, with readings taken at the girder soffits. The heavy‐haul coal traffic provided regular passages of long trains with axle loads known from mine weighings. The paper includes data on loading and number of wagons or locomotives involved in each sample for which impact data are presented. The strain readings quantify the variation of impact with degree of rail defect and also show that impacts may often exceed code values. The paper discusses the implications for bridge design.