Shear resistance of PHC slabs supported on beams: 1. Tests

Ten large-scale tests on floors comprising hollow-core slabs supported on beams were carried out. All tests ended in web shear failure of slabs close to the supports of the beam. In one test the shear resistance was not reduced, but in others was only 40–77% of the reference value measured on nonflexible supports. In one test yielding of the reinforcement in the supporting beam preceded failure. In other tests the beams did not yield and their deflection at slab failure was very small, typically L_b/1,000–L_b/300. Reduction of shear resistance is due to transverse deformation of the slab ends resulting from deflection of the beam. The reduction is so great that it must be considered in design, even though collapses due to such reduction, thanks to the high safety factors applied, have neither occurred nor are likely to occur in conventionally designed floors.