Seismic performance of two reinforced concrete moment frames with precast hollow-core floors

Precast concrete floors are widely used globally, including in seismically active regions. This paper investigates the seismic performance of hollow-core floor systems through two large-scale tests of reinforced concrete frame super-assemblies subjected to bi-directional quasi-static cyclic loading. The performance of the frame and its interaction with the floor are discussed, followed by a detailed account of the damage progression of the floor. The frame elements exhibited a ductile behaviour whilst the hollow-core floors sustained critical damage. Torsional softening of the beams with increased cracking can reduce the deformation demands on the flooring units. Floor damage was concentrated along the floor perimeter and increased with higher inter-storey drifts. A common damage progression involved flexural cracking developing near the supports and propagating into the hollow-core units as web cracks. These cracks in the unreinforced hollow-core webs first appeared at storey drift levels between 0.4% and 0.5%, within the elastic range of the frame. Across the floor plan, hollow-core units seated close to the columns showed particularly high damage susceptibility. A subsequent gravity load test conducted on a hollow-core unit confirmed a notable reduction in the load-carrying capacity following earthquake-induced damage, particularly web cracking. The tests provide unique quantitative and qualitative experimental data and highlight critical vulnerabilities of hollow-core floor systems under seismic loading, offering valuable insights to improve their design and assessment. • Large-scale tests on RC frames with hollow-core floors • Bi-directional cyclic loading reveals floor–frame interaction mechanisms • Hollow-core units near columns showed highest damage susceptibility • Web cracking in floor initiated at 0.4–0.5% storey drift • Gravity load test confirmed reduced floor capacity after seismic damage