Effects of the slab casting sequences and the drying shrinkage of concreteslabs 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 transver se cracking of slab decks has been investigated theoretically, using the al gorithm developed in the companion paper. Bending moments and the correspon ding tensile strains influencing the cracking behavior were calculated both in the construction stage and in the service stage. The effect of drying s hrinkage was considered in terms of the ultimate shrinkage strain, and it w as found to be much more important than the concrete casting sequences. Bas ed on the ACI Code, the ultimate shrinkage strain was expressed as a functi on of concrete slump and relative humidity, while the other remaining facto rs 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 e arly transverse cracking of concrete slabs. (C) 2000 Published by Elsevier Science Ltd. AU rights reserved.