Improving heavy-weight floor impact sound FEA predictions in box-frame concrete apartments: slab damping and elastic modulus

Predicting heavy-weight floor impact sound in reinforced concrete apartment buildings is crucial for ensuring acoustic comfort. This study aims to enhance the accuracy of finite element analysis based predictions of heavy-weight floor impact sound by evaluating the damping ratio and elastic modulus of concrete slabs. Field measurements were conducted in a newly constructed box-frame reinforced concrete apartment building in South Korea, where the damping ratio of slabs was measured using both an impact hammer and a standard heavy-weight impact source, rubber ball over a frequency range of 1–800 Hz. The results revealed significant variations in damping ratios depending on the impact source, with damping increasing at lower frequencies. To assess the effect of elastic modulus variations on prediction accuracy, FEA simulations were conducted with elastic modulus values set at 70 %, 80 %, 90 %, and 100 % of the design value, 25 GPa. The predicted and measured results were compared using Pearson correlation coefficients and root mean squared error analysis. Among the four floor plan types analyzed, three exhibited the highest accuracy at 70 % of the design elastic modulus, while one type showed better agreement at 100 %. This study confirms that using the damping ratio obtained from the same impact source as the measurement improves prediction accuracy. Additionally, accounting for the natural vibration mode of the slab when selecting the elastic modulus enhances the precision of heavy-weight floor impact sound predictions. These findings contribute to the optimization of floating floor system designs by mitigating resonance phenomena in reinforced concrete apartment buildings.