Composite and Steel Construction compendium

摘要

The first three articles in this series focused on composite beams and slabs in which the concrete element is cast in situ. However, it is also possible to form the concrete flange of a composite beam using precast units, be they solid or hollow-core. It is a form of construction that can be particularly appropriate in certain circumstances - as well as demonstrating the usual benefits of composite construction such as reduced steel beam weight/depth. In particular, using precast units may facilitate greater spacing of secondary beams and efficient use of composite construction in semi-exposed applications (such as car parks). If no concrete topping is needed then the 'dry construction' may facilitate work on site. Although the use of profiled decking has the advantage of reducing the amount of crane time needed to construct a floor (because individual sheets can be manually placed) precast units offer the benefit of providing a more robust floor from the moment they are in position.