Tensile membranes

Tensile membrane behavior requires continuous reinforcement steel to support in-plane stesses. Two-way slabs and flat slabs, with fixed or simple supports, can usually satisfy the requirements for tensile membrane resistance. Design with tensile membrane resistance is the same as for flexural resistance since the moment capacity of the section is used to determine ultimate resistance. Tensile membrane resistance at 8 degree rotation must be at least... 

The walls are 12 ft (366 cm) from floor slab to roof. The shorter walls are 66.67 ft (2,032 cm) long, a 5.6 to 1 height to width ratio. Therefore all walls will be analyzed as one way beams pinned at the base by a crossed reinforcing configuration at the slab level (similar to Figure 8.10), and pinned at the top due to a thinner roof slab (Figure 8,11), The wall is assumed to be unrestrained (for axial forces) at the top end and will not respond in tensile membrane action. 

Figure 5.2). Panels can be quite strong since this is a very efficient structural action however, end anchorage is extremely important to achieving significant capacity. Resistance to blast loads of more than 2-4 psi (14-28 kPa) will normally require tensile membrane response. 

The metal building cladding will fail in flexure at a low overpressure unless girt spacings are low. Tensile membrane response is possible however, care must be paid to detailing to ensure that membrane response can be achieved. Tension membrane response can also be exhibited by girts and purlins. For this example problem, alt elements will be designed for flexure. 

R. Blum Tensile membrane structures, in Air Supported Structures The State of the Art, The Institution of Structural Engineers Symposium, London,1980... 

A typical tensile membrane structure of the open covering type (photo John Chilton). 

Devulder T, Wilson R and Chilton JC (2007a), The thermal behaviour of buildings incorporating single skin tensile membrane structures . International Journal of Low-Carbon Technologies, 2(2), 195-213... 

The presence of macrovoids in hoUow-fiber membranes is a serious drawback since it increases the fragUity of the fiber and limits its abUity to withstand hydrauhc pressures. Such fibers have lower elongation and tensile strength. 

Data for thermal movement of various bitumens and felts and for composite membranes have been given (1). These describe the development of a thermal shock factor based on strength factors and the linear thermal expansion coefficient. Tensile and flexural fatigue tests on roofing membranes were taken at 21 and 18°C, and performance criteria were recommended. A study of four types of fluid-appHed roofing membranes under cycHc conditions showed that they could not withstand movements of <1.0 mm over joiats. The limitations of present test methods for new roofing materials, such as prefabricated polymeric and elastomeric sheets and Hquid-appHed membranes, have also been described (1). For evaluation, both laboratory and field work are needed. 

Live and dead loads generate hoop forces in the area of the roof-to-sheU junction for a tank having a cone roof. For dead loads plus Hve loads, the roof-to-sheU junction is assumed to carry most of the tensile forces generated. The minimum area required is computed assuming that the membrane force transmitted to the roof-to-sheU junction varies with the sine of the angle of the roof ... 

Films of the copolymers are, as with Nafion, saponified and used for permselective membranes. They have a much higher tensile strength than the Du Pont material and are also claimed to have a higher ion exchange capacity. 

The processes for manufacturing microporous membranes can be broadly divided into wet processes and dry processes. Both processes usually employ one or more orientation steps to impart porosity and/or increase tensile strength. Figure 2 shows scanning electron micrographs of surfaces of separators made by each process. 

Superficially phosphorylated chitosan membranes prepared from the reaction of orthophosphoric acid and urea in DMF, showed ionic conductivity about one order of magnitude larger compared to the unmodified chitosan membranes. The crystallinity of the phosphorylated chitosan membranes and the corresponding swelling indices changed pronouncedly, but these membranes did not lose either tensile strength or thermal stability [234]. 

Tensile forces electrically induced in a charged-collagen membrane which supports a gradient in neutral salt concentration have also been measured [7], The observed force density of oriented collagen fiber was 1 N/cm2 within 5 min on application of an electric field with a current of 0.12 mA/cm2. This value was much smaller than the force density induced by an increase in NaCl concentration. 

PVA has also been extensively used for immobilization of biocatalysts in a membranous form. As compared to PAAm, PVA is more hydrophilic and having adhesive property with better tensile strength in dry conditions. But it has high swelling index and dissolves readily in water when not cross-linked. PVA can be cross-linked using a variety of reagents including... 

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