If the separation distance is large enough, these can be more effective than a single concrete panel. Details of the STC ratings were discussed in Chapter 10.Īt higher frequencies, separately supported gypboard partitions that have a high critical frequency and a large air space are a good choice. Usually at least 10 to 15 cm (4 to 6 inches) of spacing is required. Double concrete or cmu walls can be used, but the spacing between panels must be sufficiently large that the two are not coupled through the air gap.
Fully grouted cmu blocks or brick can provide nearly as much mass and stiffness however, concrete blocks have significant porosity and must be sealed with an oil-based paint or plaster to realize the full effectiveness of their mass. Short-span concrete slabs have both high mass and a large intrinsic stiffness and thus give excellent low-frequency transmission loss. Stiffness can be increased by decreasing the support span and by increasing the bending stiffness. The structural supports are wood or metal studs for walls, and concrete, steel, or wood-joist systems for floors.Īt low frequencies providing adequate stiffness and mass are the most important factors in achieving high transmission loss values. The most common materials are concrete, concrete masonry units (cmu), stucco, gypsum plaster, gypboard, and wood or metal sheets in various combinations. In actual building practice there are relatively few construction materials that are utilized, and knowledge of transmission loss theory is very helpful in properly applying them. Marshall Long, in Architectural Acoustics (Second Edition), 2014 General Principles The 2 × 4 s are levered away from the plywood, protruding nails nipped off and the sheets taken down carefully one at a time. A disadvantage to setting plywood against a frame is that disassembly is more time-consuming. Another advantage is that the lumber used to build the frame can be reused elsewhere in the house.
One advantage to setting forms using a frame wall approach is that plywood sheets can be cut and fit into a seam pattern that can correlate to interior room details or to the placement of windows or other significant architectural elements. The project illustrated took a crew of three men ten days to erect. Block-outs for doors and windows were built and braced with 2 × 4 s and 2 × 6 s. Forms for the entire perimeter of the roughly 30 × 50 foot room were set to full wall height, eliminating the need for shut-offs. The method shown in the accompanying photographs illustrates conventional wood framing, in which a 2 × 4 frame wall is built on the slab, fixed into place along the inside wall line, then sheeted with the backing material (in this case 3/4″ HDO plywood). The most common are wood framing, pre-fabricated form panels, manufactured aluminum concrete forming systems, sheet metal studs or custom framing components. There are many different methods for constructing a plywood form. Easton, in Modern Earth Buildings, 2012 15.3.1 Simple forming The belts are then finally inspected and packed.ĭ. The other operations, like buckle attaching and edge-setting punching, are then carried out according to the design. After pasting, the belts are stitched with the help of stitching machine. Similarly, the lining of the same sizes of required material is also cut. Belt manufacturing design process Process of manufactureĪfter selection of a suitable material, the belts of different sizes are cut by a strap-cutting machine and skived from the edges. One specialized type of belt is the utility belt or police duty belt, which includes pockets for carrying items that the wearer needs for prompt use and loops to hang larger items. The leg belt is another fashionable article of clothing which, as the name suggests, one wears upon the leg.
Ī breast belt is a belt worn by women that holds their breasts up, making them appear larger or more prominent underneath clothing.īelts are also used in judo, karate, and other martial arts, where different colors may indicate rank or skill.Instead of wearing a conventional belt, skateboarders often wear shoelaces in belt loops to hold their pants up. A studded belt is typically made of leather or similar materials, and is decorated with metal studs.