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h2. How do I obtain collector forces within a floor diaphragm?

*Answer:* The collector forces within a floor diaphragm may be measured through the following process:
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# Define a semi-rigid diaphragm, then apply diaphragm forces, as shown in Figure 1:
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{center-text}Figure 1 - Apply diaphragm forces{center-text}
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# For a given [load case|kb:Load case], display any stress or [shell|kb:Shell] force, as shown in Figure 2:
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{center-text}Figure 2 - Display stress or shell force{center-text}
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# Where maximum chord forces are expected, draw or define a section cut, as shown in Figure 3:
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{center-text}Figure 3 - Maximum chord forces{center-text}
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# Moments about the Z-axis represent in-plane moments. Ensure that the resultant-force angle is 90 in order to enforce vertical line, then select Refresh, as shown in Figure 4:
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{center-text}Figure 4 - In-plane moment{center-text}
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# Compression and tension chord forces are then given as the value of each Z-axis moment divided by slab width, as shown in Figure 5:
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{center-text}Figure 5 - Compression and tension chord forces{center-text}
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# For shear and collector forces located at the connection between the diaphragm and a shear wall, draw or define a section cut next to the support which follows the wall direction, as shown in Figure 6:
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{center-text}Figure 6 - Shear and collector forces{center-text}
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# Again, ensure that the resultant-force angle is 90, and refresh as necessary. Given this example model, the shear/collector force, which is presented in F1, is 2559 lbs., as shown in Figure 7:
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{center-text}Figure 7 - Shear and collector forces
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# Local axis of section cut  1, 2 and Z are  similar to a frame element, resultant force angle indicates angle between X global axis and section cut local 1 axis
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h1. See Also

* [Rigid vs. semi-rigid diaphragm|Rigid vs. Semi-rigid diaphragm] article

* [etabs:Accidental eccentricity design] article