The galvanized welded wire mesh for skeleton in gym is firm and cost-effective.
For a 22000 m3 gymnasium and its capacity is for 1300 seats, the cylindrical space sound absorber is the key structure for the acoustic transformation engineering. Through careful planning and repeated tests, we designed galvanized welded wire mesh as the skeleton of the cylindrical space sound absorber. This kind of sound absorber is not only low-cost, but also save the construction cost because of the simple structure. The cost could save for about 40% than the conventional and it doesn’t break the budget. After the completion the identification shows that the acoustic transformation of the target has been achieved, and the sound absorption effect is nice.
The sound absorber structure design
Space sound absorber can be designed for different shapes, cross-shaped for the Shanghai Huangpu gymnasium, five-pointed star with dodecahedron for Asian Games Village University Student Gymnasium, whorl shaped for the glory stadium and there are also flat shape, conical, waist drum shape and so on. No matter how the shape is, three based parts are porous sound absorbing material, skeleton and mask & finishing materials.
The effect of the skeleton is to support the space sound absorber and the wood skeleton and the light steel skeleton are the premier choice. To save the cost, we usually do not buy the light steel skeleton but cut the expanded plate to the strips and bend them to the "L" shape to be the skeleton.
We choose the cylindrical space sound absorber after many tests. On one hand, the cylindrical space sound absorber owns a higher sound absorption coefficient, on the other hand it's easy to get the shape of the cylindrical space sound absorber. The low frequency sound absorption coefficient would increase when the diameter is bigger. But the bigger the diameter is the worse sound absorber stiffness gets. And the cost is too high for the firm skeleton. After the test, we choose the diameter of 390 mm and 17 gauge galvanized welded wire mesh as the skeleton. For this kind of welded wire mesh, the mesh opening is 1" × 1" and each roll is 30.48 m. We cut for 1.245 m welded wire mesh and rolls it into a cylinder to make the skeleton. The junction is winded with iron wires without welding. According to the side area, the skeleton is only 8.58 yuan per square meter and it’s much cheaper than the light steel skeleton.
The centrifugal glass wool felt made in Shanghai is 1.2 m in width and can roll to the cylinder with its diameter 390 mm. It’s easy to arrange the cylinder into the skeleton.
As the absorbent cover material, the nylon cloth is colorful, cheap and owns good sound performance. Firstly the nylon cloth is made to the pocket and put it on the skeleton and then sews the opening to the skeleton. For the aesthetics, the colorful nylon cloth is sewn to the middle of the skeleton.
The space sound absorber is hung to the grid with 8 gauge iron wire. The space sound absorber can’t block the lighting and speaker and we place it on the same plane with the light.
After completion, the instrument was used for acoustic measurement, and the followings are the results.
- The reverberation time: the design is achieved. According to the reaction of the experts and audience, the sound is clear during the sports game and the music sound quality is nice. The acoustic effect is improved greatly.
- The sound field uniformity: the test result under the electro acoustic system is that the sound field is uniform with hanging the space sound absorber.