Shear-torsion interaction tests on single hollow core slabs

To clarify the interaction of shear and torsion in prestressed hollow core slabs, 15 load tests on single prestressed hollow core units were carried out. The slabs were 1.2 m in width, 7 m in length and either 200 or 400 mm in depth. The ends of the slabs were simply supported. In 13 tests the loads comprised one or two point loads close to support. In two tests there was a uniform transverse line load close to one support while the slab unit was twisted by eccentric loads at the ends. In ten tests the slabs were placed on neoprene strips with no end grouting. In these tests the transverse bending made the slab fail longitudinally first, which in most cases resulted in a lower resistance than that predicted using traditional design methods. In five tests the conditions were more realistic, i.e. the slab ends were grouted and stiffened by supporting beams or spreader beams above the slab ends. In these tests the observed resistances were of the same order or higher than those predicted using the conventional calculation methods. However, some observed stiffnesses and resistances deviated so much from the predicted results that the conventional calculation methods have to be evaluated by comparison with numerical methods