Investigación sobre la compresión máxima en bielas por esfuerzo cortante en piezas prefabricadas de hormigón pretensado con armaduras pretesas

Research on the ultimate compression stresses in concrete struts due to shear in precast prestressed bridge beams

The new limitation on ultimate compression of web concrete in shear analysis included in Eurocode EC-2 will force the European precast bridge beams manufacturers to change the formworks of their beams, or reduce their applications. The authors of this paper, after having critically analyzed the most representative shear tests and the up-to-date shear theories of Nielsen and Collins, demonstrate that the Eurocode EC-2 is conservative in this issue, because the prestressed concrete beams, thanks to the compression introduced by the prestressing, present higher compression strengths of web concrete than reinforced concrete beams. As a result, the authors suggest to include in the EC-2 a factor to increase the compressive strength of web concrete in prestressed concrete beams. This factor was already proposed by Nielsen in previous stages of EC-2. In order to experimentally verify these statements, the paper also includes the description of the project of several shear tests on precast prestressed bridge beams, which are going to be carried out the next few months.