Concentrated Load Capacity of Prestressed Hollow Core Floors: Research Based on Full-Scale Experimental Investigation

The geometry of precast prestressed hollow-core cross-sections, production-induced variability in thin-walled concrete properties, and the use of exclusively longitudinal strands as reinforcement present challenges in designing hollow-core floors under concentrated loads. These loads induce complex stress states in webs and flanges, largely governed by concrete tensile strength. While individual hollow-core units have been widely studied, experimental data on full floor systems remain limited despite their expected higher load capacity. To address this gap, an experimental program was conducted on single elements and full floor systems subjected to concentrated loads up to failure. Clear differences in behavior were observed. Single elements exhibited ductile failure governed by shear and flexure, whereas full floor systems failed in a brittle manner dominated by torsional and transverse effects. Interaction between adjacent units and tying systems increased the load capacity relative to isolated elements; however, the magnitude of this enhancement depended on the specimen and load location, with enhancement ratios ranging from 1.09 to 1.49 at edge positions and from 2.03 to 2.51 at central positions. Despite the brittle failure modes, the structural integrity was preserved. Differences were also found between material properties obtained from standard-sized and drilled core specimens. Nevertheless, numerical models based on standard specimen properties showed good agreement with experiments and were not significantly affected by variations in tensile strength, indicating that full floor systems are less sensitive to concrete tensile strength than single elements.