I have a project that has two hockey rinks and a gymnasium which are “Sprung Instant Structures” which are really steel or aluminum frames covered by a teflon-coated architectural membrane. Think of a large permanent tent.
Does anyone have any experience modeling these spaces and how did you define the absorption characteristics of the membrane?
I have not had the need to model such a structure but I have installed many temporary systems in them over the years. The structures are quite transparent to bass frequencies and as such will require more bass reinforcement than you might expect. There is almost no boundary loading to effectively utilise for bass augmentation and the transparency generally results in low frequency spill and subsequent environmental noise complaints.
I hope this information will be of some assistance to you.
Sorry for this late responce… I was registered to this forum recently.
This data is taken from an old data of Tokyo dome, which has a large area of membrane. The absorption coefficient of membrane (actually transparency coefficient) varies by the structure, weight and tension of the membrane, but this might be a good reference to start from.
This is a measured absorption coeffeicient used for the actual architectual design for Tokyo dome.
125Hz 250Hz 500Hz 1kHz 2kHz 4kHz
0.38 0.39 0.42 0.5 0.54 0.53
Also this is a modeified data used for matching RT60 in Modeler to the measured.
0.46 0.39 0.41 0.42 0.43 0.53
Quite matches to the experience of Ray, I guess.
Hope this helps,