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General Questions

1. I have noted that the 2012 North American Specification Section, AISI S100, E3.3.1 requires mf equal to 0.75 for bearing calculation when the type of bearing connection is "single shear and outside sheets of double shear connections without washers under both the bolt head and nut, or with only one washer." Would the 0.75 factor apply to the case of an anchor bolt attaching a sill plate to a concrete foundation? Or can mf be taken a 1.0 by assuming the concrete mass is a big washer?

2. Section E4.4.2 of the Specification, AISI S100, deals with pull-over effects of screws in panels. Is it appropriate to use this equation for evaluating the pull-over possibility of a girt attached to a column my A307 bolts?

3. Can the section properties for a re-entrant deck profile be computed using the Specification?

4. Do the web crippling provisions of Section C3.4.1 of the Specification, AISI S100, apply to re-entrant deck profiles?

5. Section E.2.2.1.2 of the Specification applies to welding of thinner sheet to thicker sheet, how thin can the thicker bottom sheet be when using these equations?

6. When evaluating web crippling for a flat pan standing seam roof panel, can the standing seam clip which holds the lap down be considered a fastened to the support condition?

7. When evaluating the web crippling capacity of a flat pan standing seam roof panel, should the multi-web deck coefficients be used?

Question No. 1:

I have noted that the 2012 North American Specification Section, AISI S100, E3.3.1 requires mf equal to 0.75 for bearing calculation when the type of bearing connection is "single shear and outside sheets of double shear connections without washers under both the bolt head and nut, or with only one washer." Would the 0.75 factor apply to the case of an anchor bolt attaching a sill plate to a concrete foundation? Or can mf be taken a 1.0 by assuming the concrete mass is a big washer?

Answer No. 1

I believe is the 0.75 factor or some factor less than 1.0 would be appropriate. My reasoning is the use of the 1.0 factor is based on bolted connection tests were there was a nut and bolt head directly in contact with washer. The nut and bolt head would be applying pressure against the washer and connection sheets. The anchor bolt would likely not apply the same pressure on both sides of the connection sheets.

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Question No. 2:

Section E4.4.2 of the Specification, AISI S100, deals with pull-over effects of screws in panels. Is it appropriate to use this equation for evaluating the pull-over possibility of a girt attached to a column my A307 bolts?

Answer No. 2

The pull-over equation is based on tests with thin sheets as typically used for wall panels or decks. These thin sheets have a significant amount of deformation and therefore the applied stress is a combined shear and tension in the sheet around the perimeter of the fastener head. I would expect less deformation of the girt flange and therefore less tension affect. The applied stress I believe would be closer to shear alone. Thus, Section E4.4.2 would be conservative. It may be more appropriate to just treat this design situation as a shear rupture with P n = 0.6 F u A, where A = the perimeter or assumed perimeter around the bolt head.

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Question No. 3:

Can the section properties for a re-entrant deck profile be computed using the Specification, AISI S100?

Answer No. 3

The sectional properties for a re-entrant deck profile can be calculated using the provisions of Section B of the North American Specification, AISI S100.

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Question No. 4:

Do the web crippling provisions of Section C3.4.1 of the Specification, AISI S100, apply to re-entrant deck profiles?

Answer No. 4

Wallace and Schuster have determined that re-entrant deck sections behave similar to fastened multi-web deck sections. This behavior trend was found to be valid regardless of support conditions. Based on the results of their tests on end-one-flange loading, Wallace and Schuster recommended that the Specification be amended to include re-entrant deck profiles. Thus, the Specification limitation that the web inclination be less than or equal to 90 degrees will be eliminated. A summary of Wallace and Schuster's study can be found on pages 183 and 184 of the Proceedings of the 17 th International Specialty Conference on Cold-Formed Steel Structures, November 4 & 5, 2004.

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Question No. 5:

Section E.2.2.1.2 of the Specification, AISI S100, applies to welding of thinner sheet to thicker sheet, how thin can the thicker bottom sheet be when using these equations?

Answer No. 5

The Cornell University test program that serves as the basis for these equations included tests for which the thinnest bottom sheet was 0.065in. (i.e. nominally 16 ga.).

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Question No. 6:

When evaluating web crippling for a flat pan standing seam roof panel, can the standing seam clip which holds the lap down be considered a fastened to the support condition?

Answer No. 6

Because the clip does not restrain the flat of the panel, the panel should be evaluated as unrestrained.

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Question No. 7:

When evaluating the web crippling capacity of a flat pan standing seam roof panel, should the multi-web deck coefficients be used?

Answer No. 7

Because multi-web deck coefficients are based on tests of trapezoidal profiles that are a continuum at the corrugation and the flat pan panel is not, the multi-web deck coefficients may not be applicable. I suggest using the Z-section coefficients to evaluate the web crippling of each web and then adding the web crippling capacities to determine the support reaction.

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