Effects of the slab casting sequences and the drying shrinkage of concrete slabs on the short-term and long-term behavior of composite steel box girder bridges. Part 2

In this study, the effect of slab concrete placing sequence on the transverse cracking of slab decks has been investigated theoretically, using the algorithm developed in the companion paper. Bending moments and the corresponding tensile strains influencing the cracking behavior were calculated both in the construction stage and in the service stage. The effect of drying shrinkage was considered in terms of the ultimate shrinkage strain, and it was found to be much more important than the concrete casting sequences. Based on the ACI Code, the ultimate shrinkage strain was expressed as a function of concrete slump and relative humidity, while the other remaining factors such as unit weight of cement and air content were assumed in accordance with the typical values in mixed concrete. Finally, field recommendations in terms of concrete slump and relative humidity are suggested to prevent early transverse cracking of concrete slabs.