Low frequency sound insulation analysis and evaluation of stiffened building structures

• A sound transmission loss prediction method for stiffened structures.
• Both the effects of boundary conditions and stiffeners are considered.
• Experiment results agree well with the prediction results.
• A single-number rating method is proposed.
• Structural sound insulation can be improved by properly adding the stiffeners.

The sound transmission loss (STL) of a stiffened building structure is investigated using a coupled finite element and boundary element method. This STL prediction method takes into account both the effects of boundary condition and the stiffener and allows for an efficient computation of a plate structure with arbitrary boundary conditions and with arbitrary located stiffeners. Experimental measurements with a stiffened plate system are carried out to validate the proposed prediction method. The predictions agree well with the experimental data. The stiffened plate system designed for the experiment has the attraction of simplicity and flexibility and could be a good example for the design of a practical stiffened building structure. A single-number rating method is also proposed for the assessment of structural sound insulation. The rating procedure is similar to the international standard ASTM E413-10, but new reference contours are defined to make the method suitable for sound insulation assessment in the low-frequency range. The proposed methods are subsequently applied to parametric studies that examine the effects of the stiffener on the sound insulation performance of practical glass structures. The possibility of improving sound insulation performance of a building structure by using the stiffener is thereby demonstrated.