初期構造計画のための床スラブ内平均重量床衝撃音遮断性能の簡易予測法

Abstract

Prediction of floor impact sound from a heavy impact source is necessary for the structural design of apartment buildings. However, this is generally impossible to achieve for each room in the building because the room layout has yet to be decided at the structural design stage. As a statistical approach to this problem, we propose average floor impact sound pressure levels as evaluation measures for the structural design of apartment buildings. This is the average value for all rooms that can be located on a concrete slab surrounded by beams. We used two types of single-number quantity; the A-weighted impact sound pressure level (JIS A 1419-2) generated by a rubber ball (JIS A 1418-2) and the impact sound pressure level (L-number) (JIS A 1419-2) generated by a small automobile tire (JIS A 1418-2). Average floor impact sound pressure levels were calculated using the finite element method under conditions where the slab size ranged from 4×4 meters to 8×16 meters with various thicknesses. Then, the relationship between the average floor impact sound pressure level and the size of the concrete slab was examined. It was found that the average floor impact sound pressure level tends to increase with a decrease in slab size. Furthermore, average A-weighted impact sound pressure levels and the logarithm of first natural frequencies of the slab were proportional for slabs of constant thickness. On the other hand, the average L-number is affected by not only first natural frequencies, but also second and third natural frequencies. From the results, simple formulas were derived to predict average floor impact sound pressure levels from lower natural frequencies, the thickness of the slabs, and some corrections.