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The increasing availability of mass timber panels has expanded the possibilities for using timber-concrete-composite (TCC) flat floors beyond the traditional TCC T-beams. While TCC floors often easily satisfy ultimate limit state requirements, their stiffness, vibration characteristics, and long-term performance are critical design considerations. This research aimed to validate the bending, vibration, and long-term performance for nine different TCC floor systems through full-size tests with a span of 5.8 m. The tested floor systems used laminated-veneer-lumber, laminated-strand lumber, and cross-laminated-timber (CLT) panels connected to a concrete slab with and without an interlayer. Three types of shear connections were employed: self-tapping screws; glued-in steel mesh; and a combination of STS and adhesive bond. First, the shear connection properties were determined via 54 small-scale push-out tests. Then, 18 floors were tested in bending and vibration shortly after fabrication, and an additional nine floors were subjected to service loading for 32 months under variable climatic conditions, after which they were subjected to bending and vibration tests. The results confirmed that the calculations based on the γ-method accurately predict the stiffness, natural frequency, and governing failure modes of TCC floors. The long-term exposure to service loading had minimal effect (within 10%) on resistance, stiffness, and natural frequency of TCC floors, except for the TCC using CLT, which showed the highest creep deflection and stiffness reduction among the tested configurations.
Tannert et al. (Sat,) studied this question.