Constructions composites et précontraintes en acier-béton

I. In this kind of construction it is recognized that there is an intimate bond between concrete and steel. This bond, which rules out any relative movement between the two materials, may be achieved either by studs electrically welded to the steel, or by the prestress itself—cables or bolts with a high elastic limit. Studies can be effected in accordance with two methods of calculation. The first, theoretical method, is based on the assumption that creep is the linear function of the logarithm of time. In the second, approximate method, the composite and prestressed beam of steel-concrete is calculated as a homogeneous beam in which the steel section is replaced by an equivalent section of concrete.

lI.A few examples of Belgian aceomplishments:

1. The Herstal bridges on the Meuse and on the Albert canal of the « Cantilever » type, and statically determinate design;
2. The Floreffe bridge on the Sambre, Willstress system;
3. The Belgian Cité de la Radio-Télévision;
4. The Ulnion Economique in Brussels.

III. Willstress beams have been tested in the laboratories of the Universities of Brussels and of Ghent, and new tests are in progress at the University of Liège.