Early-age shrinkage and slab casting sequences in a long steel-concrete composite viaduct

ABSTRACT This paper presents a study on the effectiveness of different casting sequences to control the cracking tendency in a long continuous steel-concrete composite viaduct. The main features of the early-age behaviour of concretes are addressed and the relative modelling options are discussed. Then, the application on a real viaduct with 12 spans of different length is presented considering a continuous and two fractionated sequences of casting. The importance in the selection of the casting sequence and of the segment length is discussed. The thermal shrinkage and the weight of new segments confirmed to be the main cause of the slab premature cracking. The enhanced tensile creep may reduce stresses which remain below the concrete tensile strength even in the long term.