10.4 basis of slab types in regards to shrinkage

As detailed in section 10.4 the shrinkage effects occur as a result of restraint being provided by various means. In formulating this manual, only items which are known can be accounted for. As most items are a function of the overall building structure, the only aspect which can be covered in this manual is the restraint provided by the internal restraint of the steel. All other forms can only be accounted for by the designer of each specific project.

It is therefore imperative that the designer identify the slab system which is applicable to the project. Various slab types are detailed from simply supported through to multispan, and are referred to as either “restrained” or “unrestrained”. The designer must recognize whether or not the building provides “restraint” to the slab system and design accordingly. This manual can only take into account “unrestrained” slabs, i.e. slabs which are free to shrink in both directions in the plane of the floor.