Developing an erection scheme for a large bridge

Abstract

In the erection of large bridges the structure is successively analysed at each critical stage in the sequence. Invariably such structures are erected by first building the primary structural members, either by cantilevering them forward or lifting them into position, and following this by adding such secondary members as cantilevers, cross members and concrete slabs. The effect of these secondary members is to change the structural characteristics of the bridge and consequently the analysis must be able to take account of this history throughout the sequence. The LEAP suite of programs has been used on several major bridges to analyse and develop viable erection schemes and, using FRIDAY, to assess the critical stages and identify the most highly stressed members. This paper describes in a general way the methods used, and shows examples of the procedure for the particular case of the large cable-stayed West Gate Bridge in Australia.